https://github.com/JuliaLang/julia
Tip revision: bd84fa1bad1e08b5c368999aa9b07e4382f54910 authored by Tony Kelman on 31 March 2017, 12:58:56 UTC
Tag 0.6.0-pre.beta (#21232)
Tag 0.6.0-pre.beta (#21232)
Tip revision: bd84fa1
gc.c
// This file is a part of Julia. License is MIT: http://julialang.org/license
#include "gc.h"
#ifdef __cplusplus
extern "C" {
#endif
// Protect all access to `finalizer_list_marked` and `to_finalize`.
// For accessing `ptls->finalizers`, the lock is needed if a thread
// is going to realloc the buffer (of its own list) or accessing the
// list of another thread
static jl_mutex_t finalizers_lock;
static jl_mutex_t gc_cache_lock;
/**
* Note about GC synchronization:
*
* When entering `jl_gc_collect()`, `jl_gc_running` is atomically changed from
* `0` to `1` to make sure that only one thread can be running the GC. Other
* threads that enters `jl_gc_collect()` at the same time (or later calling
* from unmanaged code) will wait in `jl_gc_collect()` until the GC is finished.
*
* Before starting the mark phase the GC thread calls `jl_safepoint_gc_start()`
* and `jl_gc_wait_for_the_world()`
* to make sure all the thread are in a safe state for the GC. The function
* activates the safepoint and wait for all the threads to get ready for the
* GC (`gc_state != 0`). It also acquires the `finalizers` lock so that no
* other thread will access them when the GC is running.
*
* During the mark and sweep phase of the GC, the threads that are not running
* the GC should either be running unmanaged code (or code section that does
* not have a GC critical region mainly including storing to the stack or
* another object) or paused at a safepoint and wait for the GC to finish.
* If a thread want to switch from running unmanaged code to running managed
* code, it has to perform a GC safepoint check after setting the `gc_state`
* flag (see `jl_gc_state_save_and_set()`. it is possible that the thread might
* have `gc_state == 0` in the middle of the GC transition back before entering
* the safepoint. This is fine since the thread won't be executing any GC
* critical region during that time).
*
* The finalizers are run after the GC finishes in normal mode (the `gc_state`
* when `jl_gc_collect` is called) with `jl_in_finalizer = 1`. (TODO:) When we
* have proper support of GC transition in codegen, we should execute the
* finalizers in unmanaged (GC safe) mode.
*/
jl_gc_num_t gc_num = {0,0,0,0,0,0,0,0,0,0,0,0,0,0};
static size_t last_long_collect_interval;
region_t regions[REGION_COUNT];
// List of marked big objects. Not per-thread. Accessed only by master thread.
bigval_t *big_objects_marked = NULL;
// finalization
// `ptls->finalizers` and `finalizer_list_marked` might have tagged pointers.
// If an object pointer has the lowest bit set, the next pointer is an unboxed
// c function pointer.
// `to_finalize` should not have tagged pointers.
arraylist_t finalizer_list_marked;
arraylist_t to_finalize;
NOINLINE uintptr_t gc_get_stack_ptr(void)
{
return (uintptr_t)jl_get_frame_addr();
}
#define should_timeout() 0
#ifdef JULIA_ENABLE_THREADING
static void jl_gc_wait_for_the_world(void)
{
for (int i = 0;i < jl_n_threads;i++) {
jl_ptls_t ptls2 = jl_all_tls_states[i];
// FIXME: The acquire load pairs with the release stores
// in the signal handler of safepoint so we are sure that
// all the stores on those threads are visible. However,
// we're currently not using atomic stores in mutator threads.
// We should either use atomic store release there too or use signals
// to flush the memory operations on those threads.
while (!ptls2->gc_state || !jl_atomic_load_acquire(&ptls2->gc_state)) {
jl_cpu_pause(); // yield?
}
}
}
#else
static inline void jl_gc_wait_for_the_world(void)
{
}
#endif
// malloc wrappers, aligned allocation
#define malloc_cache_align(sz) jl_malloc_aligned(sz, JL_CACHE_BYTE_ALIGNMENT)
#define realloc_cache_align(p, sz, oldsz) jl_realloc_aligned(p, sz, oldsz, JL_CACHE_BYTE_ALIGNMENT)
static void schedule_finalization(void *o, void *f)
{
arraylist_push(&to_finalize, o);
arraylist_push(&to_finalize, f);
}
static void run_finalizer(jl_ptls_t ptls, jl_value_t *o, jl_value_t *ff)
{
assert(!jl_typeis(ff, jl_voidpointer_type));
jl_value_t *args[2] = {ff,o};
JL_TRY {
size_t last_age = jl_get_ptls_states()->world_age;
jl_get_ptls_states()->world_age = jl_world_counter;
jl_apply(args, 2);
jl_get_ptls_states()->world_age = last_age;
}
JL_CATCH {
jl_printf(JL_STDERR, "error in running finalizer: ");
jl_static_show(JL_STDERR, ptls->exception_in_transit);
jl_printf(JL_STDERR, "\n");
}
}
// if `need_sync` is true, the `list` is the `finalizers` list of another
// thread and we need additional synchronizations
static void finalize_object(arraylist_t *list, jl_value_t *o,
arraylist_t *copied_list, int need_sync)
{
// The acquire load makes sure that the first `len` objects are valid.
// If `need_sync` is true, all mutations of the content should be limited
// to the first `oldlen` elements and no mutation is allowed after the
// new length is published with the `cmpxchg` at the end of the function.
// This way, the mutation should not conflict with the owning thread,
// which only writes to locations later than `len`
// and will not resize the buffer without acquiring the lock.
size_t len = need_sync ? jl_atomic_load_acquire(&list->len) : list->len;
size_t oldlen = len;
void **items = list->items;
for (size_t i = 0; i < len; i += 2) {
void *v = items[i];
int move = 0;
if (o == (jl_value_t*)gc_ptr_clear_tag(v, 1)) {
void *f = items[i + 1];
move = 1;
if (gc_ptr_tag(v, 1)) {
((void (*)(void*))f)(o);
}
else {
arraylist_push(copied_list, o);
arraylist_push(copied_list, f);
}
}
if (move || __unlikely(!v)) {
if (i < len - 2) {
items[i] = items[len - 2];
items[i + 1] = items[len - 1];
i -= 2;
}
len -= 2;
}
}
if (oldlen == len)
return;
if (need_sync) {
// The memset needs to be unconditional since the thread might have
// already read the length.
// The `memset` (like any other content mutation) has to be done
// **before** the `cmpxchg` which publishes the length.
memset(&items[len], 0, (oldlen - len) * sizeof(void*));
jl_atomic_compare_exchange(&list->len, oldlen, len);
}
else {
list->len = len;
}
}
// The first two entries are assumed to be empty and the rest are assumed to
// be pointers to `jl_value_t` objects
static void jl_gc_push_arraylist(jl_ptls_t ptls, arraylist_t *list)
{
void **items = list->items;
items[0] = (void*)(((uintptr_t)list->len - 2) << 1);
items[1] = ptls->pgcstack;
ptls->pgcstack = (jl_gcframe_t*)items;
}
// Same assumption as `jl_gc_push_arraylist`. Requires the finalizers lock
// to be hold for the current thread and will release the lock when the
// function returns.
static void jl_gc_run_finalizers_in_list(jl_ptls_t ptls, arraylist_t *list)
{
size_t len = list->len;
jl_value_t **items = (jl_value_t**)list->items;
jl_gc_push_arraylist(ptls, list);
JL_UNLOCK_NOGC(&finalizers_lock);
for (size_t i = 2;i < len;i += 2)
run_finalizer(ptls, items[i], items[i + 1]);
JL_GC_POP();
}
static void run_finalizers(jl_ptls_t ptls)
{
// Racy fast path:
// The race here should be OK since the race can only happen if
// another thread is writing to it with the lock held. In such case,
// we don't need to run pending finalizers since the writer thread
// will flush it.
if (to_finalize.len == 0)
return;
JL_LOCK_NOGC(&finalizers_lock);
if (to_finalize.len == 0) {
JL_UNLOCK_NOGC(&finalizers_lock);
return;
}
arraylist_t copied_list;
memcpy(&copied_list, &to_finalize, sizeof(copied_list));
if (to_finalize.items == to_finalize._space) {
copied_list.items = copied_list._space;
}
arraylist_new(&to_finalize, 0);
// empty out the first two entries for the GC frame
arraylist_push(&copied_list, copied_list.items[0]);
arraylist_push(&copied_list, copied_list.items[1]);
// This releases the finalizers lock.
jl_gc_run_finalizers_in_list(ptls, &copied_list);
arraylist_free(&copied_list);
}
JL_DLLEXPORT void jl_gc_enable_finalizers(jl_ptls_t ptls, int on)
{
int old_val = ptls->finalizers_inhibited;
int new_val = old_val + (on ? -1 : 1);
ptls->finalizers_inhibited = new_val;
if (!new_val && old_val && !ptls->in_finalizer) {
ptls->in_finalizer = 1;
run_finalizers(ptls);
ptls->in_finalizer = 0;
}
}
static void schedule_all_finalizers(arraylist_t *flist)
{
void **items = flist->items;
size_t len = flist->len;
for(size_t i = 0; i < len; i+=2) {
void *v = items[i];
void *f = items[i + 1];
if (__unlikely(!v))
continue;
if (!gc_ptr_tag(v, 1)) {
schedule_finalization(v, f);
}
else {
((void (*)(void*))f)(gc_ptr_clear_tag(v, 1));
}
}
flist->len = 0;
}
void jl_gc_run_all_finalizers(jl_ptls_t ptls)
{
for (int i = 0;i < jl_n_threads;i++) {
jl_ptls_t ptls2 = jl_all_tls_states[i];
schedule_all_finalizers(&ptls2->finalizers);
}
schedule_all_finalizers(&finalizer_list_marked);
run_finalizers(ptls);
}
static void gc_add_finalizer_(jl_ptls_t ptls, void *v, void *f)
{
int8_t gc_state = jl_gc_unsafe_enter(ptls);
arraylist_t *a = &ptls->finalizers;
// This acquire load and the release store at the end are used to
// synchronize with `finalize_object` on another thread. Apart from the GC,
// which is blocked by entering a unsafe region, there might be only
// one other thread accessing our list in `finalize_object`
// (only one thread since it needs to acquire the finalizer lock).
// Similar to `finalize_object`, all content mutation has to be done
// between the acquire and the release of the length.
size_t oldlen = jl_atomic_load_acquire(&a->len);
if (__unlikely(oldlen + 2 > a->max)) {
JL_LOCK_NOGC(&finalizers_lock);
// `a->len` might have been modified.
// Another possiblility is to always grow the array to `oldlen + 2` but
// it's simpler this way and uses slightly less memory =)
oldlen = a->len;
arraylist_grow(a, 2);
a->len = oldlen;
JL_UNLOCK_NOGC(&finalizers_lock);
}
void **items = a->items;
items[oldlen] = v;
items[oldlen + 1] = f;
jl_atomic_store_release(&a->len, oldlen + 2);
jl_gc_unsafe_leave(ptls, gc_state);
}
STATIC_INLINE void gc_add_ptr_finalizer(jl_ptls_t ptls, jl_value_t *v, void *f)
{
gc_add_finalizer_(ptls, (void*)(((uintptr_t)v) | 1), f);
}
JL_DLLEXPORT void jl_gc_add_finalizer_th(jl_ptls_t ptls, jl_value_t *v,
jl_function_t *f)
{
if (__unlikely(jl_typeis(f, jl_voidpointer_type))) {
gc_add_ptr_finalizer(ptls, v, jl_unbox_voidpointer(f));
}
else {
gc_add_finalizer_(ptls, v, f);
}
}
JL_DLLEXPORT void jl_gc_add_ptr_finalizer(jl_ptls_t ptls, jl_value_t *v, void *f)
{
gc_add_ptr_finalizer(ptls, v, f);
}
JL_DLLEXPORT void jl_finalize_th(jl_ptls_t ptls, jl_value_t *o)
{
JL_LOCK_NOGC(&finalizers_lock);
// Copy the finalizers into a temporary list so that code in the finalizer
// won't change the list as we loop through them.
// This list is also used as the GC frame when we are running the finalizers
arraylist_t copied_list;
arraylist_new(&copied_list, 0);
arraylist_push(&copied_list, NULL); // GC frame size to be filled later
arraylist_push(&copied_list, NULL); // pgcstack to be filled later
// No need to check the to_finalize list since the user is apparently
// still holding a reference to the object
for (int i = 0;i < jl_n_threads;i++) {
jl_ptls_t ptls2 = jl_all_tls_states[i];
finalize_object(&ptls2->finalizers, o, &copied_list, ptls != ptls2);
}
finalize_object(&finalizer_list_marked, o, &copied_list, 0);
if (copied_list.len > 2) {
// This releases the finalizers lock.
jl_gc_run_finalizers_in_list(ptls, &copied_list);
}
else {
JL_UNLOCK_NOGC(&finalizers_lock);
}
arraylist_free(&copied_list);
}
// GC knobs and self-measurement variables
static int64_t last_gc_total_bytes = 0;
#ifdef _P64
#define default_collect_interval (5600*1024*sizeof(void*))
static size_t max_collect_interval = 1250000000UL;
#else
#define default_collect_interval (3200*1024*sizeof(void*))
static size_t max_collect_interval = 500000000UL;
#endif
// global variables for GC stats
// Resetting the object to a young object, this is used when marking the
// finalizer list to collect them the next time because the object is very
// likely dead. This also won't break the GC invariance since these objects
// are not reachable from anywhere else.
static int mark_reset_age = 0;
/*
* The state transition looks like :
*
* ([(quick)sweep] means either a sweep or a quicksweep)
*
* <-[(quick)sweep]-
* |
* ----> GC_OLD <--[(quick)sweep && age>promotion]--
* | | |
* | | GC_MARKED (in remset) |
* | | ^ | |
* | [mark] | [mark] |
* | | | | |
* | | | | |
* [sweep] | [write barrier] | |
* | v | v |
* ----- GC_OLD_MARKED <---- |
* | ^ |
* | | |
* --[quicksweep]--- |
* |
* ========= above this line objects are old ========= |
* |
* ----[new]------> GC_CLEAN ------[mark]-----------> GC_MARKED
* | ^ |
* <-[(quick)sweep]--- | |
* --[(quick)sweep && age<=promotion]---
*/
// A quick sweep is a sweep where `!sweep_full`
// It means we won't touch GC_OLD_MARKED objects (old gen).
// When a reachable object has survived more than PROMOTE_AGE+1 collections
// it is tagged with GC_OLD during sweep and will be promoted on next mark
// because at that point we can know easily if it references young objects.
// Marked old objects that reference young ones are kept in the remset.
// When a write barrier triggers, the offending marked object is both queued,
// so as not to trigger the barrier again, and put in the remset.
#define PROMOTE_AGE 1
// this cannot be increased as is without changing :
// - sweep_page which is specialized for 1bit age
// - the size of the age storage in region_t
static int64_t scanned_bytes; // young bytes scanned while marking
static int64_t perm_scanned_bytes; // old bytes scanned while marking
static int prev_sweep_full = 1;
#define inc_sat(v,s) v = (v) >= s ? s : (v)+1
// Full collection heuristics
static int64_t live_bytes = 0;
static int64_t promoted_bytes = 0;
static int64_t last_full_live_ub = 0;
static int64_t last_full_live_est = 0;
// upper bound and estimated live object sizes
// This heuristic should be really unlikely to trigger.
// However, this should be simple enough to trigger a full collection
// when it's necessary if other heuristics are messed up.
// It is also possible to take the total memory available into account
// if necessary.
STATIC_INLINE int gc_check_heap_size(int64_t sz_ub, int64_t sz_est)
{
if (__unlikely(!last_full_live_ub || last_full_live_ub > sz_ub)) {
last_full_live_ub = sz_ub;
}
else if (__unlikely(last_full_live_ub * 3 / 2 < sz_ub)) {
return 1;
}
if (__unlikely(!last_full_live_est || last_full_live_est > sz_est)) {
last_full_live_est = sz_est;
}
else if (__unlikely(last_full_live_est * 2 < sz_est)) {
return 1;
}
return 0;
}
STATIC_INLINE void gc_update_heap_size(int64_t sz_ub, int64_t sz_est)
{
last_full_live_ub = sz_ub;
last_full_live_est = sz_est;
}
static void gc_sync_cache_nolock(jl_ptls_t ptls, jl_gc_mark_cache_t *gc_cache)
{
const int nbig = gc_cache->nbig_obj;
for (int i = 0; i < nbig; i++) {
void *ptr = gc_cache->big_obj[i];
bigval_t *hdr = (bigval_t*)gc_ptr_clear_tag(ptr, 1);
gc_big_object_unlink(hdr);
if (gc_ptr_tag(ptr, 1)) {
gc_big_object_link(hdr, &ptls->heap.big_objects);
}
else {
// Move hdr from `big_objects` list to `big_objects_marked list`
gc_big_object_link(hdr, &big_objects_marked);
}
}
gc_cache->nbig_obj = 0;
perm_scanned_bytes += gc_cache->perm_scanned_bytes;
scanned_bytes += gc_cache->scanned_bytes;
gc_cache->perm_scanned_bytes = 0;
gc_cache->scanned_bytes = 0;
}
static void gc_sync_cache(jl_ptls_t ptls)
{
JL_LOCK_NOGC(&gc_cache_lock);
gc_sync_cache_nolock(ptls, &ptls->gc_cache);
JL_UNLOCK_NOGC(&gc_cache_lock);
}
// No other threads can be running marking at the same time
static void gc_sync_all_caches_nolock(jl_ptls_t ptls)
{
for (int t_i = 0; t_i < jl_n_threads; t_i++) {
jl_ptls_t ptls2 = jl_all_tls_states[t_i];
gc_sync_cache_nolock(ptls, &ptls2->gc_cache);
}
}
STATIC_INLINE void gc_queue_big_marked(jl_ptls_t ptls, bigval_t *hdr,
int toyoung)
{
const int nentry = sizeof(ptls->gc_cache.big_obj) / sizeof(void*);
size_t nobj = ptls->gc_cache.nbig_obj;
if (__unlikely(nobj >= nentry)) {
gc_sync_cache(ptls);
nobj = 0;
}
uintptr_t v = (uintptr_t)hdr;
ptls->gc_cache.big_obj[nobj] = (void*)(toyoung ? (v | 1) : v);
ptls->gc_cache.nbig_obj = nobj + 1;
}
// `gc_setmark_tag` can be called concurrently on multiple threads.
// In all cases, the function atomically sets the mark bits and returns
// the GC bits set as well as if the tag was unchanged by this thread.
// All concurrent calls on the same object are guaranteed to be setting the
// bits to the same value.
// For normal objects, this is the bits with only `GC_MARKED` changed to `1`
// For buffers, this is the bits of the owner object.
// For `mark_reset_age`, this is `GC_MARKED` with `GC_OLD` cleared.
// The return value is `1` if the object was not marked before.
// Returning `0` can happen if another thread marked it in parallel.
STATIC_INLINE int gc_setmark_tag(jl_taggedvalue_t *o, uint8_t mark_mode,
uintptr_t tag, uint8_t *bits)
{
assert(!gc_marked(tag));
assert(gc_marked(mark_mode));
if (mark_reset_age) {
// Reset the object as if it was just allocated
mark_mode = GC_MARKED;
tag = gc_set_bits(tag, mark_mode);
}
else {
if (gc_old(tag))
mark_mode = GC_OLD_MARKED;
tag = tag | mark_mode;
assert((tag & 0x3) == mark_mode);
}
*bits = mark_mode;
tag = jl_atomic_exchange_relaxed(&o->header, tag);
verify_val(jl_valueof(o));
return !gc_marked(tag);
}
// This function should be called exactly once during marking for each big
// object being marked to update the big objects metadata.
STATIC_INLINE void gc_setmark_big(jl_ptls_t ptls, jl_taggedvalue_t *o,
uint8_t mark_mode)
{
assert(!page_metadata(o));
bigval_t *hdr = bigval_header(o);
if (mark_mode == GC_OLD_MARKED) {
ptls->gc_cache.perm_scanned_bytes += hdr->sz & ~3;
gc_queue_big_marked(ptls, hdr, 0);
}
else {
ptls->gc_cache.scanned_bytes += hdr->sz & ~3;
// We can't easily tell if the object is old or being promoted
// from the gc bits but if the `age` is `0` then the object
// must be already on a young list.
if (mark_reset_age && hdr->age) {
// Reset the object as if it was just allocated
hdr->age = 0;
gc_queue_big_marked(ptls, hdr, 1);
}
}
objprofile_count(jl_typeof(jl_valueof(o)),
mark_mode == GC_OLD_MARKED, hdr->sz & ~3);
}
// This function should be called exactly once during marking for each pool
// object being marked to update the page metadata.
STATIC_INLINE void gc_setmark_pool_(jl_ptls_t ptls, jl_taggedvalue_t *o,
uint8_t mark_mode,
jl_gc_pagemeta_t *page)
{
#ifdef MEMDEBUG
gc_setmark_big(ptls, o, mark_mode);
#else
if (mark_mode == GC_OLD_MARKED) {
ptls->gc_cache.perm_scanned_bytes += page->osize;
jl_atomic_fetch_add_relaxed(&page->nold, 1);
}
else {
ptls->gc_cache.scanned_bytes += page->osize;
if (mark_reset_age) {
page->has_young = 1;
char *page_begin = gc_page_data(o) + GC_PAGE_OFFSET;
int obj_id = (((char*)o) - page_begin) / page->osize;
uint8_t *ages = page->ages + obj_id / 8;
jl_atomic_fetch_and_relaxed(ages, ~(1 << (obj_id % 8)));
}
}
objprofile_count(jl_typeof(jl_valueof(o)),
mark_mode == GC_OLD_MARKED, page->osize);
page->has_marked = 1;
#endif
}
STATIC_INLINE void gc_setmark_pool(jl_ptls_t ptls, jl_taggedvalue_t *o,
uint8_t mark_mode)
{
gc_setmark_pool_(ptls, o, mark_mode, page_metadata(o));
}
STATIC_INLINE void gc_setmark(jl_ptls_t ptls, jl_taggedvalue_t *o,
uint8_t mark_mode, size_t sz)
{
if (sz <= GC_MAX_SZCLASS) {
gc_setmark_pool(ptls, o, mark_mode);
}
else {
gc_setmark_big(ptls, o, mark_mode);
}
}
#ifndef __cplusplus
inline
#endif
void gc_setmark_buf(jl_ptls_t ptls, void *o, uint8_t mark_mode, size_t minsz)
{
jl_taggedvalue_t *buf = jl_astaggedvalue(o);
uintptr_t tag = buf->header;
if (gc_marked(tag))
return;
uint8_t bits;
// If the object is larger than the max pool size it can't be a pool object.
// This should be accurate most of the time but there might be corner cases
// where the size estimate is a little off so we do a pool lookup to make
// sure.
if (__likely(gc_setmark_tag(buf, mark_mode, tag, &bits)) && !gc_verifying) {
if (minsz <= GC_MAX_SZCLASS) {
jl_gc_pagemeta_t *page = page_metadata(o);
if (page) {
gc_setmark_pool_(ptls, buf, bits, page);
return;
}
}
gc_setmark_big(ptls, buf, bits);
}
}
#define should_collect() (__unlikely(gc_num.allocd>0))
static inline int maybe_collect(jl_ptls_t ptls)
{
if (should_collect() || gc_debug_check_other()) {
jl_gc_collect(0);
return 1;
}
jl_gc_safepoint_(ptls);
return 0;
}
// weak references
JL_DLLEXPORT jl_weakref_t *jl_gc_new_weakref_th(jl_ptls_t ptls,
jl_value_t *value)
{
jl_weakref_t *wr = (jl_weakref_t*)jl_gc_alloc(ptls, sizeof(void*),
jl_weakref_type);
wr->value = value; // NOTE: wb not needed here
arraylist_push(&ptls->heap.weak_refs, wr);
return wr;
}
static void sweep_weak_refs(void)
{
for (int i = 0;i < jl_n_threads;i++) {
jl_ptls_t ptls2 = jl_all_tls_states[i];
size_t n = 0;
size_t ndel = 0;
size_t l = ptls2->heap.weak_refs.len;
void **lst = ptls2->heap.weak_refs.items;
if (l == 0)
continue;
while (1) {
jl_weakref_t *wr = (jl_weakref_t*)lst[n];
if (gc_marked(jl_astaggedvalue(wr)->bits.gc)) {
// weakref itself is alive
if (!gc_marked(jl_astaggedvalue(wr->value)->bits.gc))
wr->value = (jl_value_t*)jl_nothing;
n++;
}
else {
ndel++;
}
if (n >= l - ndel)
break;
void *tmp = lst[n];
lst[n] = lst[n + ndel];
lst[n+ndel] = tmp;
}
ptls2->heap.weak_refs.len -= ndel;
}
}
// big value list
// Size includes the tag and the tag is not cleared!!
JL_DLLEXPORT jl_value_t *jl_gc_big_alloc(jl_ptls_t ptls, size_t sz)
{
maybe_collect(ptls);
size_t offs = offsetof(bigval_t, header);
size_t allocsz = LLT_ALIGN(sz + offs, JL_CACHE_BYTE_ALIGNMENT);
if (allocsz < sz) // overflow in adding offs, size was "negative"
jl_throw(jl_memory_exception);
bigval_t *v = (bigval_t*)malloc_cache_align(allocsz);
if (v == NULL)
jl_throw(jl_memory_exception);
#ifdef JULIA_ENABLE_THREADING
jl_atomic_fetch_add(&gc_num.allocd, allocsz);
#else
gc_num.allocd += allocsz;
#endif
gc_num.bigalloc++;
#ifdef MEMDEBUG
memset(v, 0xee, allocsz);
#endif
v->sz = allocsz;
v->age = 0;
gc_big_object_link(v, &ptls->heap.big_objects);
return jl_valueof(&v->header);
}
// Sweep list rooted at *pv, removing and freeing any unmarked objects.
// Return pointer to last `next` field in the culled list.
static bigval_t **sweep_big_list(int sweep_full, bigval_t **pv)
{
bigval_t *v = *pv;
while (v != NULL) {
bigval_t *nxt = v->next;
int bits = v->bits.gc;
int old_bits = bits;
if (gc_marked(bits)) {
pv = &v->next;
int age = v->age;
if (age >= PROMOTE_AGE || bits == GC_OLD_MARKED) {
if (sweep_full || bits == GC_MARKED) {
bits = GC_OLD;
}
}
else {
inc_sat(age, PROMOTE_AGE);
v->age = age;
bits = GC_CLEAN;
}
v->bits.gc = bits;
}
else {
// Remove v from list and free it
*pv = nxt;
if (nxt)
nxt->prev = pv;
gc_num.freed += v->sz&~3;
#ifdef MEMDEBUG
memset(v, 0xbb, v->sz&~3);
#endif
jl_free_aligned(v);
}
gc_time_count_big(old_bits, bits);
v = nxt;
}
return pv;
}
static void sweep_big(jl_ptls_t ptls, int sweep_full)
{
gc_time_big_start();
for (int i = 0;i < jl_n_threads;i++)
sweep_big_list(sweep_full, &jl_all_tls_states[i]->heap.big_objects);
if (sweep_full) {
bigval_t **last_next = sweep_big_list(sweep_full, &big_objects_marked);
// Move all survivors from big_objects_marked list to big_objects list.
if (ptls->heap.big_objects)
ptls->heap.big_objects->prev = last_next;
*last_next = ptls->heap.big_objects;
ptls->heap.big_objects = big_objects_marked;
if (ptls->heap.big_objects)
ptls->heap.big_objects->prev = &ptls->heap.big_objects;
big_objects_marked = NULL;
}
gc_time_big_end();
}
// tracking Arrays with malloc'd storage
void jl_gc_track_malloced_array(jl_ptls_t ptls, jl_array_t *a)
{
// This is **NOT** a GC safe point.
mallocarray_t *ma;
if (ptls->heap.mafreelist == NULL) {
ma = (mallocarray_t*)malloc(sizeof(mallocarray_t));
}
else {
ma = ptls->heap.mafreelist;
ptls->heap.mafreelist = ma->next;
}
ma->a = a;
ma->next = ptls->heap.mallocarrays;
ptls->heap.mallocarrays = ma;
}
void jl_gc_count_allocd(size_t sz)
{
// This is **NOT** a GC safe point.
gc_num.allocd += sz;
}
void jl_gc_reset_alloc_count(void)
{
live_bytes += (gc_num.deferred_alloc + (gc_num.allocd + gc_num.interval));
gc_num.allocd = -(int64_t)gc_num.interval;
gc_num.deferred_alloc = 0;
}
static size_t array_nbytes(jl_array_t *a)
{
size_t sz = 0;
if (jl_array_ndims(a)==1)
sz = a->elsize * a->maxsize + (a->elsize == 1 ? 1 : 0);
else
sz = a->elsize * jl_array_len(a);
return sz;
}
static void jl_gc_free_array(jl_array_t *a)
{
if (a->flags.how == 2) {
char *d = (char*)a->data - a->offset*a->elsize;
if (a->flags.isaligned)
jl_free_aligned(d);
else
free(d);
gc_num.freed += array_nbytes(a);
}
}
static void sweep_malloced_arrays(void)
{
gc_time_mallocd_array_start();
for (int t_i = 0;t_i < jl_n_threads;t_i++) {
jl_ptls_t ptls2 = jl_all_tls_states[t_i];
mallocarray_t *ma = ptls2->heap.mallocarrays;
mallocarray_t **pma = &ptls2->heap.mallocarrays;
while (ma != NULL) {
mallocarray_t *nxt = ma->next;
int bits = jl_astaggedvalue(ma->a)->bits.gc;
if (gc_marked(bits)) {
pma = &ma->next;
}
else {
*pma = nxt;
assert(ma->a->flags.how == 2);
jl_gc_free_array(ma->a);
ma->next = ptls2->heap.mafreelist;
ptls2->heap.mafreelist = ma;
}
gc_time_count_mallocd_array(bits);
ma = nxt;
}
}
gc_time_mallocd_array_end();
}
// pool allocation
static inline jl_taggedvalue_t *reset_page(const jl_gc_pool_t *p, jl_gc_pagemeta_t *pg, jl_taggedvalue_t *fl)
{
assert(GC_PAGE_OFFSET >= sizeof(void*));
pg->nfree = (GC_PAGE_SZ - GC_PAGE_OFFSET) / p->osize;
jl_ptls_t ptls2 = jl_all_tls_states[pg->thread_n];
pg->pool_n = p - ptls2->heap.norm_pools;
memset(pg->ages, 0, GC_PAGE_SZ / 8 / p->osize + 1);
jl_taggedvalue_t *beg = (jl_taggedvalue_t*)(pg->data + GC_PAGE_OFFSET);
jl_taggedvalue_t *next = (jl_taggedvalue_t*)pg->data;
next->next = fl;
pg->has_young = 0;
pg->has_marked = 0;
pg->fl_begin_offset = -1;
pg->fl_end_offset = -1;
return beg;
}
// Add a new page to the pool. Discards any pages in `p->newpages` before.
static NOINLINE jl_taggedvalue_t *add_page(jl_gc_pool_t *p)
{
// Do not pass in `ptls` as argument. This slows down the fast path
// in pool_alloc significantly
jl_ptls_t ptls = jl_get_ptls_states();
char *data = (char*)jl_gc_alloc_page();
if (data == NULL)
jl_throw(jl_memory_exception);
jl_gc_pagemeta_t *pg = page_metadata(data + GC_PAGE_OFFSET);
pg->data = data;
pg->osize = p->osize;
pg->ages = (uint8_t*)malloc(GC_PAGE_SZ / 8 / p->osize + 1);
pg->thread_n = ptls->tid;
jl_taggedvalue_t *fl = reset_page(p, pg, NULL);
p->newpages = fl;
return fl;
}
// Size includes the tag and the tag is not cleared!!
JL_DLLEXPORT jl_value_t *jl_gc_pool_alloc(jl_ptls_t ptls, int pool_offset,
int osize)
{
// Use the pool offset instead of the pool address as the argument
// to workaround a llvm bug.
// Ref https://llvm.org/bugs/show_bug.cgi?id=27190
jl_gc_pool_t *p = (jl_gc_pool_t*)((char*)ptls + pool_offset);
#ifdef JULIA_ENABLE_THREADING
assert(ptls->gc_state == 0);
#endif
#ifdef MEMDEBUG
return jl_gc_big_alloc(ptls, osize);
#endif
// FIXME - need JL_ATOMIC_FETCH_AND_ADD here
if (__unlikely((gc_num.allocd += osize) >= 0) || gc_debug_check_pool()) {
//gc_num.allocd -= osize;
jl_gc_collect(0);
//gc_num.allocd += osize;
}
else {
jl_gc_safepoint_(ptls);
}
gc_num.poolalloc++;
// first try to use the freelist
jl_taggedvalue_t *v = p->freelist;
if (v) {
jl_taggedvalue_t *next = v->next;
p->freelist = next;
if (__unlikely(gc_page_data(v) != gc_page_data(next))) {
// we only update pg's fields when the freelist changes page
// since pg's metadata is likely not in cache
jl_gc_pagemeta_t *pg = page_metadata(v);
assert(pg->osize == p->osize);
pg->nfree = 0;
pg->has_young = 1;
}
return jl_valueof(v);
}
// if the freelist is empty we reuse empty but not freed pages
v = p->newpages;
jl_taggedvalue_t *next = (jl_taggedvalue_t*)((char*)v + osize);
// If there's no pages left or the current page is used up,
// we need to use the slow path.
char *cur_page = gc_page_data((char*)v - 1);
if (__unlikely(!v || cur_page + GC_PAGE_SZ < (char*)next)) {
if (v) {
// like the freelist case,
// but only update the page metadata when it is full
jl_gc_pagemeta_t *pg = page_metadata((char*)v - 1);
assert(pg->osize == p->osize);
pg->nfree = 0;
pg->has_young = 1;
v = *(jl_taggedvalue_t**)cur_page;
}
// Not an else!!
if (!v)
v = add_page(p);
next = (jl_taggedvalue_t*)((char*)v + osize);
}
p->newpages = next;
return jl_valueof(v);
}
int jl_gc_classify_pools(size_t sz, int *osize)
{
if (sz > GC_MAX_SZCLASS)
return -1;
size_t allocsz = sz + sizeof(jl_taggedvalue_t);
int klass = jl_gc_szclass(allocsz);
*osize = jl_gc_sizeclasses[klass];
return (int)(intptr_t)(&((jl_ptls_t)0)->heap.norm_pools[klass]);
}
// sweep phase
int64_t lazy_freed_pages = 0;
// Returns pointer to terminal pointer of list rooted at *pfl.
static jl_taggedvalue_t **sweep_page(jl_gc_pool_t *p, jl_gc_pagemeta_t *pg, jl_taggedvalue_t **pfl, int sweep_full, int osize)
{
char *data = pg->data;
uint8_t *ages = pg->ages;
jl_taggedvalue_t *v = (jl_taggedvalue_t*)(data + GC_PAGE_OFFSET);
char *lim = (char*)v + GC_PAGE_SZ - GC_PAGE_OFFSET - osize;
size_t old_nfree = pg->nfree;
size_t nfree;
int freedall = 1;
int pg_skpd = 1;
if (!pg->has_marked) {
// lazy version: (empty) if the whole page was already unused, free it
// eager version: (freedall) free page as soon as possible
// the eager one uses less memory.
// FIXME - need to do accounting on a per-thread basis
// on quick sweeps, keep a few pages empty but allocated for performance
if (!sweep_full && lazy_freed_pages <= default_collect_interval / GC_PAGE_SZ) {
jl_taggedvalue_t *begin = reset_page(p, pg, p->newpages);
p->newpages = begin;
begin->next = (jl_taggedvalue_t*)0;
lazy_freed_pages++;
}
else {
jl_gc_free_page(data);
}
nfree = (GC_PAGE_SZ - GC_PAGE_OFFSET) / osize;
goto done;
}
// For quick sweep, we might be able to skip the page if the page doesn't
// have any young live cell before marking.
if (!sweep_full && !pg->has_young) {
assert(!prev_sweep_full || pg->prev_nold >= pg->nold);
if (!prev_sweep_full || pg->prev_nold == pg->nold) {
// the position of the freelist begin/end in this page
// is stored in its metadata
if (pg->fl_begin_offset != (uint16_t)-1) {
*pfl = page_pfl_beg(pg);
pfl = (jl_taggedvalue_t**)page_pfl_end(pg);
}
freedall = 0;
nfree = pg->nfree;
goto done;
}
}
pg_skpd = 0;
{ // scope to avoid clang goto errors
int has_marked = 0;
int has_young = 0;
int16_t prev_nold = 0;
int pg_nfree = 0;
jl_taggedvalue_t **pfl_begin = NULL;
uint8_t msk = 1; // mask for the age bit in the current age byte
while ((char*)v <= lim) {
int bits = v->bits.gc;
if (!gc_marked(bits)) {
*pfl = v;
pfl = &v->next;
pfl_begin = pfl_begin ? pfl_begin : pfl;
pg_nfree++;
*ages &= ~msk;
}
else { // marked young or old
if (*ages & msk || bits == GC_OLD_MARKED) { // old enough
// `!age && bits == GC_OLD_MARKED` is possible for
// non-first-class objects like `jl_binding_t`
if (sweep_full || bits == GC_MARKED) {
bits = v->bits.gc = GC_OLD; // promote
}
prev_nold++;
}
else {
assert(bits == GC_MARKED);
bits = v->bits.gc = GC_CLEAN; // unmark
has_young = 1;
}
has_marked |= gc_marked(bits);
*ages |= msk;
freedall = 0;
}
v = (jl_taggedvalue_t*)((char*)v + osize);
msk <<= 1;
if (!msk) {
msk = 1;
ages++;
}
}
assert(!freedall);
pg->has_marked = has_marked;
pg->has_young = has_young;
if (pfl_begin) {
pg->fl_begin_offset = (char*)pfl_begin - data;
pg->fl_end_offset = (char*)pfl - data;
}
else {
pg->fl_begin_offset = -1;
pg->fl_end_offset = -1;
}
pg->nfree = pg_nfree;
if (sweep_full) {
pg->nold = 0;
pg->prev_nold = prev_nold;
}
}
nfree = pg->nfree;
done:
gc_time_count_page(freedall, pg_skpd);
gc_num.freed += (nfree - old_nfree) * osize;
return pfl;
}
static void sweep_pool_region(jl_taggedvalue_t ***pfl, int region_i, int sweep_full)
{
region_t *region = ®ions[region_i];
// the actual sweeping
int ub = 0;
int lb = region->lb;
for (int pg_i = 0; pg_i <= region->ub; pg_i++) {
uint32_t line = region->allocmap[pg_i];
if (line) {
ub = pg_i;
for (int j = 0; j < 32; j++) {
if ((line >> j) & 1) {
jl_gc_pagemeta_t *pg = ®ion->meta[pg_i*32 + j];
int p_n = pg->pool_n;
int t_n = pg->thread_n;
jl_ptls_t ptls2 = jl_all_tls_states[t_n];
jl_gc_pool_t *p = &ptls2->heap.norm_pools[p_n];
int osize = pg->osize;
pfl[t_n * JL_GC_N_POOLS + p_n] = sweep_page(p, pg, pfl[t_n * JL_GC_N_POOLS + p_n], sweep_full, osize);
}
}
}
else if (pg_i < lb) {
lb = pg_i;
}
}
region->ub = ub;
region->lb = lb;
}
static void gc_sweep_other(jl_ptls_t ptls, int sweep_full)
{
sweep_malloced_arrays();
sweep_big(ptls, sweep_full);
}
static void gc_pool_sync_nfree(jl_gc_pagemeta_t *pg, jl_taggedvalue_t *last)
{
assert(pg->fl_begin_offset != (uint16_t)-1);
char *cur_pg = gc_page_data(last);
// Fast path for page that has no allocation
jl_taggedvalue_t *fl_beg = (jl_taggedvalue_t*)(cur_pg + pg->fl_begin_offset);
if (last == fl_beg)
return;
int nfree = 0;
do {
nfree++;
last = last->next;
} while (gc_page_data(last) == cur_pg);
pg->nfree = nfree;
}
static void gc_sweep_pool(int sweep_full)
{
gc_time_pool_start();
lazy_freed_pages = 0;
jl_taggedvalue_t ***pfl = (jl_taggedvalue_t ***) alloca(jl_n_threads * JL_GC_N_POOLS * sizeof(jl_taggedvalue_t**));
// update metadata of pages that were pointed to by freelist or newpages from a pool
// i.e. pages being the current allocation target
for (int t_i = 0; t_i < jl_n_threads; t_i++) {
jl_ptls_t ptls2 = jl_all_tls_states[t_i];
for (int i = 0; i < JL_GC_N_POOLS; i++) {
jl_gc_pool_t *p = &ptls2->heap.norm_pools[i];
jl_taggedvalue_t *last = p->freelist;
if (last) {
jl_gc_pagemeta_t *pg = page_metadata(last);
gc_pool_sync_nfree(pg, last);
pg->has_young = 1;
}
p->freelist = NULL;
pfl[t_i * JL_GC_N_POOLS + i] = &p->freelist;
last = p->newpages;
if (last) {
char *last_p = (char*)last;
jl_gc_pagemeta_t *pg = page_metadata(last_p - 1);
assert(last_p - gc_page_data(last_p - 1) >= GC_PAGE_OFFSET);
pg->nfree = (GC_PAGE_SZ - (last_p - gc_page_data(last_p - 1))) / p->osize;
pg->has_young = 1;
}
p->newpages = NULL;
}
}
for (int i = 0; i < REGION_COUNT; i++) {
if (!regions[i].pages)
break;
sweep_pool_region(pfl, i, sweep_full);
}
// null out terminal pointers of free lists
for (int t_i = 0; t_i < jl_n_threads; t_i++) {
for (int i = 0; i < JL_GC_N_POOLS; i++) {
*pfl[t_i * JL_GC_N_POOLS + i] = NULL;
}
}
gc_time_pool_end(sweep_full);
}
// mark phase
static jl_value_t **mark_stack = NULL;
static jl_value_t **mark_stack_base = NULL;
static size_t mark_stack_size = 0;
static size_t mark_sp = 0;
static void grow_mark_stack(void)
{
size_t newsz = mark_stack_size>0 ? mark_stack_size*2 : 32000;
size_t offset = mark_stack - mark_stack_base;
mark_stack_base = (jl_value_t**)realloc(mark_stack_base, newsz*sizeof(void*));
if (mark_stack_base == NULL) {
jl_printf(JL_STDERR, "Couldn't grow mark stack to : %" PRIuPTR "\n",
(uintptr_t)newsz);
exit(1);
}
mark_stack = mark_stack_base + offset;
mark_stack_size = newsz;
}
JL_DLLEXPORT void jl_gc_queue_root(jl_value_t *ptr)
{
jl_ptls_t ptls = jl_get_ptls_states();
jl_taggedvalue_t *o = jl_astaggedvalue(ptr);
#ifndef JULIA_ENABLE_THREADING
// Disable this assert since it can happen with multithreading (same
// with the ones in gc_queue_binding) when two threads are writing
// to the same object.
assert(o->bits.gc == GC_OLD_MARKED);
#endif
// The modification of the `gc_bits` is not atomic but it
// should be safe here since GC is not allowed to run here and we only
// write GC_OLD to the GC bits outside GC. This could cause
// duplicated objects in the remset but that shouldn't be a problem.
o->bits.gc = GC_MARKED;
arraylist_push(ptls->heap.remset, ptr);
ptls->heap.remset_nptr++; // conservative
}
void gc_queue_binding(jl_binding_t *bnd)
{
jl_ptls_t ptls = jl_get_ptls_states();
jl_taggedvalue_t *buf = jl_astaggedvalue(bnd);
#ifndef JULIA_ENABLE_THREADING
// Will fail for multithreading. See `jl_gc_queue_root`
assert(buf->bits.gc == GC_OLD_MARKED);
#endif
buf->bits.gc = GC_MARKED;
arraylist_push(&ptls->heap.rem_bindings, bnd);
}
static void gc_scan_obj_(jl_ptls_t ptls, jl_value_t *v, int d,
uintptr_t tag, uint8_t bits);
static void gc_mark_obj(jl_ptls_t ptls, jl_value_t *v,
uintptr_t tag, uint8_t bits);
#ifdef JL_DEBUG_BUILD
static void *volatile gc_findval; // for usage from gdb, for finding the gc-root for a value
#endif
// Returns whether the object is young
STATIC_INLINE int gc_push_root(jl_ptls_t ptls, void *v, int d) // v isa jl_value_t*
{
#ifdef JL_DEBUG_BUILD
if (v == gc_findval)
jl_raise_debugger();
#endif
assert(v != NULL);
jl_taggedvalue_t *o = jl_astaggedvalue(v);
verify_val(v);
uintptr_t tag = o->header;
if (!gc_marked(tag)) {
uint8_t bits;
if (__likely(gc_setmark_tag(o, GC_MARKED, tag, &bits))) {
tag = tag & ~(uintptr_t)15;
if (!gc_verifying)
gc_mark_obj(ptls, (jl_value_t*)v, tag, bits);
gc_scan_obj_(ptls, (jl_value_t*)v, d, tag, bits);
}
return !gc_old(bits);
}
return !gc_old(tag);
}
// TODO rename this as it is misleading now
void jl_gc_setmark(jl_ptls_t ptls, jl_value_t *v)
{
jl_taggedvalue_t *o = jl_astaggedvalue(v);
uintptr_t tag = o->header;
if (!gc_marked(tag)) {
uint8_t bits;
if (__likely(gc_setmark_tag(o, GC_MARKED, tag, &bits)) && !gc_verifying) {
gc_setmark_pool(ptls, o, bits);
}
}
}
NOINLINE static int gc_mark_module(jl_ptls_t ptls, jl_module_t *m,
int d, int8_t bits)
{
size_t i;
int refyoung = 0;
void **table = m->bindings.table;
for(i=1; i < m->bindings.size; i+=2) {
if (table[i] != HT_NOTFOUND) {
jl_binding_t *b = (jl_binding_t*)table[i];
gc_setmark_buf(ptls, b, bits, sizeof(jl_binding_t));
void *vb = jl_astaggedvalue(b);
verify_parent1("module", m, &vb, "binding_buff");
(void)vb;
if (b->value != NULL) {
verify_parent2("module", m, &b->value, "binding(%s)",
jl_symbol_name(b->name));
refyoung |= gc_push_root(ptls, b->value, d);
}
if (b->globalref != NULL)
refyoung |= gc_push_root(ptls, b->globalref, d);
}
}
// this is only necessary because bindings for "using" modules
// are added only when accessed. therefore if a module is replaced
// after "using" it but before accessing it, this array might
// contain the only reference.
for(i=0; i < m->usings.len; i++) {
refyoung |= gc_push_root(ptls, m->usings.items[i], d);
}
if (m->parent) {
refyoung |= gc_push_root(ptls, m->parent, d);
}
return refyoung;
}
// Handle the case where the stack is only partially copied.
STATIC_INLINE uintptr_t gc_get_stack_addr(void *_addr, uintptr_t offset,
uintptr_t lb, uintptr_t ub)
{
uintptr_t addr = (uintptr_t)_addr;
if (addr >= lb && addr < ub)
return addr + offset;
return addr;
}
STATIC_INLINE uintptr_t gc_read_stack(void *_addr, uintptr_t offset,
uintptr_t lb, uintptr_t ub)
{
uintptr_t real_addr = gc_get_stack_addr(_addr, offset, lb, ub);
return *(uintptr_t*)real_addr;
}
static void gc_mark_stack(jl_ptls_t ptls, jl_gcframe_t *s, uintptr_t offset,
uintptr_t lb, uintptr_t ub, int d)
{
while (s != NULL) {
jl_value_t ***rts = (jl_value_t***)(((void**)s) + 2);
size_t nroots = gc_read_stack(&s->nroots, offset, lb, ub);
size_t nr = nroots >> 1;
if (nroots & 1) {
for (size_t i = 0; i < nr; i++) {
void **slot = (void**)gc_read_stack(&rts[i], offset, lb, ub);
void *obj = (void*)gc_read_stack(slot, offset, lb, ub);
if (obj != NULL) {
gc_push_root(ptls, obj, d);
}
}
}
else {
for (size_t i=0; i < nr; i++) {
void *obj = (void*)gc_read_stack(&rts[i], offset, lb, ub);
if (obj) {
gc_push_root(ptls, obj, d);
}
}
}
s = (jl_gcframe_t*)gc_read_stack(&s->prev, offset, lb, ub);
}
}
static void gc_mark_task_stack(jl_ptls_t ptls, jl_task_t *ta, int d, int8_t bits)
{
gc_scrub_record_task(ta);
int stkbuf = (ta->stkbuf != (void*)(intptr_t)-1 && ta->stkbuf != NULL);
int16_t tid = ta->tid;
jl_ptls_t ptls2 = jl_all_tls_states[tid];
if (stkbuf) {
#ifdef COPY_STACKS
gc_setmark_buf(ptls, ta->stkbuf, bits, ta->bufsz);
#else
// stkbuf isn't owned by julia for the root task
if (ta != ptls2->root_task) {
gc_setmark_buf(ptls, ta->stkbuf, bits, ta->ssize);
}
#endif
}
if (ta == ptls2->current_task) {
gc_mark_stack(ptls, ptls2->pgcstack, 0, 0, (uintptr_t)-1, d);
}
else if (stkbuf) {
uintptr_t offset = 0;
uintptr_t lb = 0;
uintptr_t ub = (uintptr_t)-1;
#ifdef COPY_STACKS
ub = (uintptr_t)ptls2->stackbase;
lb = ub - ta->ssize;
offset = (uintptr_t)ta->stkbuf - lb;
#endif
gc_mark_stack(ptls, ta->gcstack, offset, lb, ub, d);
}
}
NOINLINE static void gc_mark_task(jl_ptls_t ptls, jl_task_t *ta,
int d, int8_t bits)
{
if (ta->parent) gc_push_root(ptls, ta->parent, d);
gc_push_root(ptls, ta->tls, d);
gc_push_root(ptls, ta->consumers, d);
gc_push_root(ptls, ta->donenotify, d);
gc_push_root(ptls, ta->exception, d);
if (ta->backtrace) gc_push_root(ptls, ta->backtrace, d);
if (ta->start) gc_push_root(ptls, ta->start, d);
if (ta->result) gc_push_root(ptls, ta->result, d);
gc_mark_task_stack(ptls, ta, d, bits);
}
void gc_mark_object_list(jl_ptls_t ptls, arraylist_t *list, size_t start)
{
void **items = list->items;
size_t len = list->len;
for (size_t i = start;i < len;i++) {
void *v = items[i];
if (__unlikely(!v))
continue;
if (gc_ptr_tag(v, 1)) {
v = gc_ptr_clear_tag(v, 1);
i++;
assert(i < len);
}
gc_push_root(ptls, v, 0);
}
}
STATIC_INLINE void gc_assert_datatype(jl_datatype_t *vt)
{
if (__likely(jl_is_datatype(vt)))
return;
jl_printf(JL_STDOUT, "GC error (probable corruption) :\n");
gc_debug_print_status();
jl_(vt);
gc_debug_critical_error();
abort();
}
// for chasing down unwanted references
/*
static jl_value_t *lookforme = NULL;
JL_DLLEXPORT void jl_gc_lookfor(jl_value_t *v) { lookforme = v; }
*/
#define MAX_MARK_DEPTH 400
// Scan a marked object `v` and recursively mark its children.
// The object will be queued on the mark stack when recursion depth
// becomes too high.
// It does so assuming that the tag of the (marked) object is `tag`.
// If `v` is `GC_OLD_MARKED` and some of its children are `GC_MARKED` (young),
// `v` is added to the remset
static void gc_scan_obj_(jl_ptls_t ptls, jl_value_t *v, int d,
uintptr_t tag, uint8_t bits)
{
assert(v != NULL);
assert(gc_marked(bits));
jl_datatype_t *vt = (jl_datatype_t*)tag;
#ifdef JL_DEBUG_BUILD
gc_assert_datatype(vt); // should have checked in `gc_mark_obj`
#endif
int refyoung = 0, nptr = 0;
assert(vt != jl_symbol_type);
// weakref should not be marked
if (vt == jl_weakref_type)
return;
// fast path
if (vt->layout->npointers == 0)
return;
d++;
if (d >= MAX_MARK_DEPTH)
goto queue_the_root;
// some values have special representations
if (vt == jl_simplevector_type) {
size_t l = jl_svec_len(v);
jl_value_t **data = jl_svec_data(v);
nptr += l;
for(size_t i=0; i < l; i++) {
jl_value_t *elt = data[i];
if (elt != NULL) {
verify_parent2("svec", v, &data[i], "elem(%d)", (int)i);
refyoung |= gc_push_root(ptls, elt, d);
}
}
}
else if (vt->name == jl_array_typename) {
jl_array_t *a = (jl_array_t*)v;
jl_array_flags_t flags = a->flags;
if (flags.how == 3) {
jl_value_t *owner = jl_array_data_owner(a);
refyoung |= gc_push_root(ptls, owner, d);
goto ret;
}
else if (flags.how == 1) {
void *val_buf = jl_astaggedvalue((char*)a->data -
a->offset * a->elsize);
verify_parent1("array", v, &val_buf,
"buffer ('loc' addr is meaningless)");
(void)val_buf;
gc_setmark_buf(ptls, (char*)a->data - a->offset * a->elsize,
bits, array_nbytes(a));
}
if (flags.ptrarray && a->data != NULL) {
size_t l = jl_array_len(a);
if (l > 100000 && d > MAX_MARK_DEPTH-10) {
// don't mark long arrays at high depth, to try to avoid
// copying the whole array into the mark queue
goto queue_the_root;
}
else {
nptr += l;
void *data = a->data;
for (size_t i=0; i < l; i++) {
jl_value_t *elt = ((jl_value_t**)data)[i];
if (elt != NULL) {
verify_parent2("array", v, &((jl_value_t**)data)[i], "elem(%d)", (int)i);
refyoung |= gc_push_root(ptls, elt, d);
}
}
}
}
}
else if (vt == jl_module_type) {
// should increase nptr here
refyoung |= gc_mark_module(ptls, (jl_module_t*)v, d, bits);
}
else if (vt == jl_task_type) {
// ditto nptr
gc_mark_task(ptls, (jl_task_t*)v, d, bits);
// tasks should always be remarked since we do not trigger the write barrier
// for stores to stack slots
refyoung = 1;
}
else {
int nf = (int)jl_datatype_nfields(vt);
uint32_t npointers = vt->layout->npointers;
nptr += (npointers & 0xff) << (npointers & 0x300);
for(int i=0; i < nf; i++) {
if (jl_field_isptr(vt, i)) {
jl_value_t **slot = (jl_value_t**)((char*)v +
jl_field_offset(vt, i));
jl_value_t *fld = *slot;
if (fld) {
verify_parent2("object", v, slot, "field(%d)", i);
refyoung |= gc_push_root(ptls, fld, d);
}
}
}
}
ret:
if ((bits == GC_OLD_MARKED) && refyoung && !gc_verifying) {
ptls->heap.remset_nptr += nptr;
// v is an old object referencing young objects
arraylist_push(ptls->heap.remset, v);
}
return;
queue_the_root:
if (mark_sp >= mark_stack_size)
grow_mark_stack();
mark_stack[mark_sp++] = (jl_value_t*)v;
}
STATIC_INLINE void gc_scan_obj(jl_ptls_t ptls, jl_value_t *v, int d,
uintptr_t tag)
{
gc_scan_obj_(ptls, v, d, tag & ~(uintptr_t)15, tag & 0xf);
}
// Update the metadata of a marked object (without scanning it).
static void gc_mark_obj(jl_ptls_t ptls, jl_value_t *v,
uintptr_t tag, uint8_t bits)
{
assert(v != NULL);
assert(gc_marked(bits));
jl_taggedvalue_t *o = jl_astaggedvalue(v);
jl_datatype_t *vt = (jl_datatype_t*)(tag & ~(uintptr_t)15);
gc_assert_datatype(vt);
// Symbols are always marked
assert(vt != jl_symbol_type);
// some values have special representations
if (vt == jl_simplevector_type) {
size_t l = jl_svec_len(v);
gc_setmark(ptls, o, bits, l * sizeof(void*) + sizeof(jl_svec_t));
}
else if (vt->name == jl_array_typename) {
jl_array_t *a = (jl_array_t*)v;
jl_array_flags_t flags = a->flags;
if (flags.pooled)
gc_setmark_pool(ptls, o, bits);
else
gc_setmark_big(ptls, o, bits);
if (flags.how == 2) {
objprofile_count(jl_malloc_tag, bits == GC_OLD_MARKED,
array_nbytes(a));
if (bits == GC_OLD_MARKED) {
ptls->gc_cache.perm_scanned_bytes += array_nbytes(a);
}
else {
ptls->gc_cache.scanned_bytes += array_nbytes(a);
}
}
}
else if (vt == jl_module_type) {
gc_setmark(ptls, o, bits, sizeof(jl_module_t));
}
else if (vt == jl_task_type) {
gc_setmark(ptls, o, bits, sizeof(jl_task_t));
}
else if (vt == jl_string_type) {
gc_setmark(ptls, o, bits, jl_string_len(v) + sizeof(size_t) + 1);
}
else {
gc_setmark(ptls, o, bits, jl_datatype_size(vt));
}
}
void visit_mark_stack(jl_ptls_t ptls)
{
while (mark_sp > 0 && !should_timeout()) {
jl_value_t *v = mark_stack[--mark_sp];
assert(jl_astaggedvalue(v)->bits.gc);
gc_scan_obj(ptls, v, 0, jl_astaggedvalue(v)->header);
}
assert(!mark_sp);
}
extern jl_array_t *jl_module_init_order;
extern jl_typemap_entry_t *call_cache[N_CALL_CACHE];
extern jl_array_t *jl_all_methods;
static void jl_gc_mark_thread_local(jl_ptls_t ptls, jl_ptls_t ptls2)
{
// `current_module` might not have a value when the thread is not
// running.
if (ptls2->current_module)
gc_push_root(ptls, ptls2->current_module, 0);
gc_push_root(ptls, ptls2->current_task, 0);
gc_push_root(ptls, ptls2->root_task, 0);
gc_push_root(ptls, ptls2->exception_in_transit, 0);
gc_push_root(ptls, ptls2->task_arg_in_transit, 0);
}
// mark the initial root set
static void mark_roots(jl_ptls_t ptls)
{
// modules
gc_push_root(ptls, jl_main_module, 0);
gc_push_root(ptls, jl_internal_main_module, 0);
// invisible builtin values
if (jl_an_empty_vec_any != NULL)
gc_push_root(ptls, jl_an_empty_vec_any, 0);
if (jl_module_init_order != NULL)
gc_push_root(ptls, jl_module_init_order, 0);
gc_push_root(ptls, jl_cfunction_list.unknown, 0);
gc_push_root(ptls, jl_anytuple_type_type, 0);
gc_push_root(ptls, jl_ANY_flag, 0);
for (size_t i = 0; i < N_CALL_CACHE; i++)
if (call_cache[i])
gc_push_root(ptls, call_cache[i], 0);
if (jl_all_methods != NULL)
gc_push_root(ptls, jl_all_methods, 0);
// gc_push_root(ptls, jl_unprotect_stack_func, 0);
// constants
gc_push_root(ptls, jl_typetype_type, 0);
gc_push_root(ptls, jl_emptytuple_type, 0);
}
// find unmarked objects that need to be finalized from the finalizer list "list".
// this must happen last in the mark phase.
static void sweep_finalizer_list(arraylist_t *list)
{
void **items = list->items;
size_t len = list->len;
for (size_t i=0; i < len; i+=2) {
void *v0 = items[i];
int is_cptr = gc_ptr_tag(v0, 1);
void *v = gc_ptr_clear_tag(v0, 1);
if (__unlikely(!v0)) {
// remove from this list
if (i < len - 2) {
items[i] = items[len - 2];
items[i + 1] = items[len - 1];
i -= 2;
}
len -= 2;
continue;
}
void *fin = items[i+1];
int isfreed = !gc_marked(jl_astaggedvalue(v)->bits.gc);
int isold = (list != &finalizer_list_marked &&
jl_astaggedvalue(v)->bits.gc == GC_OLD_MARKED &&
(is_cptr || jl_astaggedvalue(fin)->bits.gc == GC_OLD_MARKED));
if (isfreed || isold) {
// remove from this list
if (i < len - 2) {
items[i] = items[len - 2];
items[i + 1] = items[len - 1];
i -= 2;
}
len -= 2;
}
if (isfreed) {
// schedule finalizer or execute right away if it is not julia code
if (is_cptr) {
((void (*)(void*))fin)(jl_data_ptr(v));
continue;
}
schedule_finalization(v, fin);
}
if (isold) {
// The caller relies on the new objects to be pushed to the end of
// the list!!
arraylist_push(&finalizer_list_marked, v0);
arraylist_push(&finalizer_list_marked, fin);
}
}
list->len = len;
}
// collector entry point and control
static volatile uint32_t jl_gc_disable_counter = 0;
JL_DLLEXPORT int jl_gc_enable(int on)
{
jl_ptls_t ptls = jl_get_ptls_states();
int prev = !ptls->disable_gc;
ptls->disable_gc = (on == 0);
if (on && !prev) {
// disable -> enable
if (jl_atomic_fetch_add(&jl_gc_disable_counter, -1) == 1) {
gc_num.allocd += gc_num.deferred_alloc;
gc_num.deferred_alloc = 0;
}
}
else if (prev && !on) {
// enable -> disable
jl_atomic_fetch_add(&jl_gc_disable_counter, 1);
// check if the GC is running and wait for it to finish
jl_gc_safepoint_(ptls);
}
return prev;
}
JL_DLLEXPORT int jl_gc_is_enabled(void)
{
jl_ptls_t ptls = jl_get_ptls_states();
return !ptls->disable_gc;
}
JL_DLLEXPORT int64_t jl_gc_total_bytes(void)
{
// Sync this logic with `base/util.jl:GC_Diff`
return (gc_num.total_allocd + gc_num.deferred_alloc +
gc_num.allocd + gc_num.interval);
}
JL_DLLEXPORT uint64_t jl_gc_total_hrtime(void)
{
return gc_num.total_time;
}
JL_DLLEXPORT jl_gc_num_t jl_gc_num(void)
{
return gc_num;
}
JL_DLLEXPORT int64_t jl_gc_diff_total_bytes(void)
{
int64_t oldtb = last_gc_total_bytes;
int64_t newtb = jl_gc_total_bytes();
last_gc_total_bytes = newtb;
return newtb - oldtb;
}
void jl_gc_sync_total_bytes(void) {last_gc_total_bytes = jl_gc_total_bytes();}
static void jl_gc_premark(jl_ptls_t ptls2)
{
arraylist_t *remset = ptls2->heap.remset;
ptls2->heap.remset = ptls2->heap.last_remset;
ptls2->heap.last_remset = remset;
ptls2->heap.remset->len = 0;
ptls2->heap.remset_nptr = 0;
// avoid counting remembered objects & bindings twice
// in `perm_scanned_bytes`
size_t len = remset->len;
void **items = remset->items;
for (size_t i = 0; i < len; i++) {
jl_value_t *item = (jl_value_t*)items[i];
objprofile_count(jl_typeof(item), 2, 0);
jl_astaggedvalue(item)->bits.gc = GC_OLD_MARKED;
}
len = ptls2->heap.rem_bindings.len;
items = ptls2->heap.rem_bindings.items;
for (size_t i = 0; i < len; i++) {
void *ptr = items[i];
jl_astaggedvalue(ptr)->bits.gc = GC_OLD_MARKED;
}
}
static void jl_gc_mark_remset(jl_ptls_t ptls, jl_ptls_t ptls2)
{
size_t len = ptls2->heap.last_remset->len;
void **items = ptls2->heap.last_remset->items;
for (size_t i = 0; i < len; i++) {
jl_value_t *item = (jl_value_t*)items[i];
gc_scan_obj(ptls, item, 0, jl_astaggedvalue(item)->header);
}
int n_bnd_refyoung = 0;
len = ptls2->heap.rem_bindings.len;
items = ptls2->heap.rem_bindings.items;
for (size_t i = 0; i < len; i++) {
jl_binding_t *ptr = (jl_binding_t*)items[i];
// A null pointer can happen here when the binding is cleaned up
// as an exception is thrown after it was already queued (#10221)
if (!ptr->value) continue;
if (gc_push_root(ptls, ptr->value, 0)) {
items[n_bnd_refyoung] = ptr;
n_bnd_refyoung++;
}
}
ptls2->heap.rem_bindings.len = n_bnd_refyoung;
}
static void jl_gc_mark_ptrfree(jl_ptls_t ptls)
{
// Pointer-free objects, can be marked concurrently
jl_mark_box_caches(ptls);
jl_gc_setmark(ptls, (jl_value_t*)jl_emptysvec);
jl_gc_setmark(ptls, jl_emptytuple);
jl_gc_setmark(ptls, jl_true);
jl_gc_setmark(ptls, jl_false);
}
// Only one thread should be running in this function
static int _jl_gc_collect(jl_ptls_t ptls, int full)
{
uint64_t t0 = jl_hrtime();
int64_t last_perm_scanned_bytes = perm_scanned_bytes;
assert(mark_sp == 0);
// 1. fix GC bits of objects in the remset.
for (int t_i = 0; t_i < jl_n_threads; t_i++)
jl_gc_premark(jl_all_tls_states[t_i]);
for (int t_i = 0; t_i < jl_n_threads; t_i++) {
jl_ptls_t ptls2 = jl_all_tls_states[t_i];
// 2.1. mark every object in the `last_remsets` and `rem_binding`
jl_gc_mark_remset(ptls, ptls2);
// 2.2. mark every thread local root
jl_gc_mark_thread_local(ptls, ptls2);
}
// 3. walk roots
mark_roots(ptls);
visit_mark_stack(ptls);
gc_num.since_sweep += gc_num.allocd + (int64_t)gc_num.interval;
gc_settime_premark_end();
gc_time_mark_pause(t0, scanned_bytes, perm_scanned_bytes);
int64_t actual_allocd = gc_num.since_sweep;
// marking is over
// 4. check for objects to finalize
// Record the length of the marked list since we need to
// mark the object moved to the marked list from the
// `finalizer_list` by `sweep_finalizer_list`
size_t orig_marked_len = finalizer_list_marked.len;
for (int i = 0;i < jl_n_threads;i++) {
jl_ptls_t ptls2 = jl_all_tls_states[i];
sweep_finalizer_list(&ptls2->finalizers);
}
if (prev_sweep_full) {
sweep_finalizer_list(&finalizer_list_marked);
orig_marked_len = 0;
}
for (int i = 0;i < jl_n_threads;i++) {
jl_ptls_t ptls2 = jl_all_tls_states[i];
gc_mark_object_list(ptls, &ptls2->finalizers, 0);
}
gc_mark_object_list(ptls, &finalizer_list_marked, orig_marked_len);
// "Flush" the mark stack before flipping the reset_age bit
// so that the objects are not incorrectly resetted.
visit_mark_stack(ptls);
mark_reset_age = 1;
// Reset the age and old bit for any unmarked objects referenced by the
// `to_finalize` list. These objects are only reachable from this list
// and should not be referenced by any old objects so this won't break
// the GC invariant.
gc_mark_object_list(ptls, &to_finalize, 0);
visit_mark_stack(ptls);
mark_reset_age = 0;
gc_settime_postmark_end();
// Flush everything in mark cache
gc_sync_all_caches_nolock(ptls);
int64_t live_sz_ub = live_bytes + actual_allocd;
int64_t live_sz_est = scanned_bytes + perm_scanned_bytes;
int64_t estimate_freed = live_sz_ub - live_sz_est;
gc_verify(ptls);
gc_stats_all_pool();
gc_stats_big_obj();
objprofile_printall();
objprofile_reset();
gc_num.total_allocd += gc_num.since_sweep;
if (!prev_sweep_full)
promoted_bytes += perm_scanned_bytes - last_perm_scanned_bytes;
// 5. next collection decision
int not_freed_enough = estimate_freed < (7*(actual_allocd/10));
int nptr = 0;
for (int i = 0;i < jl_n_threads;i++)
nptr += jl_all_tls_states[i]->heap.remset_nptr;
int large_frontier = nptr*sizeof(void*) >= default_collect_interval; // many pointers in the intergen frontier => "quick" mark is not quick
int sweep_full;
int recollect = 0;
if ((full || large_frontier ||
((not_freed_enough || promoted_bytes >= gc_num.interval) &&
(promoted_bytes >= default_collect_interval || prev_sweep_full)) ||
gc_check_heap_size(live_sz_ub, live_sz_est)) &&
gc_num.pause > 1) {
gc_update_heap_size(live_sz_ub, live_sz_est);
recollect = full;
if (large_frontier)
gc_num.interval = last_long_collect_interval;
if (not_freed_enough || large_frontier) {
if (gc_num.interval < default_collect_interval) {
gc_num.interval = default_collect_interval;
}
else if (gc_num.interval <= 2*(max_collect_interval/5)) {
gc_num.interval = 5 * (gc_num.interval / 2);
}
}
last_long_collect_interval = gc_num.interval;
sweep_full = 1;
promoted_bytes = 0;
}
else {
gc_num.interval = default_collect_interval / 2;
sweep_full = gc_sweep_always_full;
}
if (sweep_full)
perm_scanned_bytes = 0;
scanned_bytes = 0;
// 5. start sweeping
sweep_weak_refs();
gc_sweep_other(ptls, sweep_full);
gc_scrub();
gc_verify_tags();
gc_sweep_pool(sweep_full);
// sweeping is over
// 6. if it is a quick sweep, put back the remembered objects in queued state
// so that we don't trigger the barrier again on them.
for (int t_i = 0;t_i < jl_n_threads;t_i++) {
jl_ptls_t ptls2 = jl_all_tls_states[t_i];
if (!sweep_full) {
for (int i = 0; i < ptls2->heap.remset->len; i++) {
jl_astaggedvalue(ptls2->heap.remset->items[i])->bits.gc = GC_MARKED;
}
for (int i = 0; i < ptls2->heap.rem_bindings.len; i++) {
void *ptr = ptls2->heap.rem_bindings.items[i];
jl_astaggedvalue(ptr)->bits.gc = GC_MARKED;
}
}
else {
ptls2->heap.remset->len = 0;
ptls2->heap.rem_bindings.len = 0;
}
}
uint64_t gc_end_t = jl_hrtime();
uint64_t pause = gc_end_t - t0;
gc_final_pause_end(t0, gc_end_t);
gc_time_sweep_pause(gc_end_t, actual_allocd, live_bytes,
estimate_freed, sweep_full);
gc_num.full_sweep += sweep_full;
prev_sweep_full = sweep_full;
gc_num.allocd = -(int64_t)gc_num.interval;
live_bytes += -gc_num.freed + gc_num.since_sweep;
gc_num.pause += !recollect;
gc_num.total_time += pause;
gc_num.since_sweep = 0;
gc_num.freed = 0;
return recollect;
}
JL_DLLEXPORT void jl_gc_collect(int full)
{
jl_ptls_t ptls = jl_get_ptls_states();
if (jl_gc_disable_counter) {
gc_num.deferred_alloc += (gc_num.allocd + gc_num.interval);
gc_num.allocd = -(int64_t)gc_num.interval;
return;
}
gc_debug_print();
int8_t old_state = jl_gc_state(ptls);
ptls->gc_state = JL_GC_STATE_WAITING;
// `jl_safepoint_start_gc()` makes sure only one thread can
// run the GC.
if (!jl_safepoint_start_gc()) {
// Multithread only. See assertion in `safepoint.c`
jl_gc_state_set(ptls, old_state, JL_GC_STATE_WAITING);
return;
}
JL_TIMING(GC);
// Now we are ready to wait for other threads to hit the safepoint,
// we can do a few things that doesn't require synchronization.
jl_gc_mark_ptrfree(ptls);
// no-op for non-threading
jl_gc_wait_for_the_world();
if (!jl_gc_disable_counter) {
JL_LOCK_NOGC(&finalizers_lock);
if (_jl_gc_collect(ptls, full)) {
jl_gc_mark_ptrfree(ptls);
int ret = _jl_gc_collect(ptls, 0);
(void)ret;
assert(!ret);
}
JL_UNLOCK_NOGC(&finalizers_lock);
}
// no-op for non-threading
jl_safepoint_end_gc();
jl_gc_state_set(ptls, old_state, JL_GC_STATE_WAITING);
// Only disable finalizers on current thread
// Doing this on all threads is racy (it's impossible to check
// or wait for finalizers on other threads without dead lock).
if (!ptls->finalizers_inhibited) {
int8_t was_in_finalizer = ptls->in_finalizer;
ptls->in_finalizer = 1;
run_finalizers(ptls);
ptls->in_finalizer = was_in_finalizer;
}
}
void mark_all_roots(jl_ptls_t ptls)
{
for (size_t i = 0; i < jl_n_threads; i++)
jl_gc_mark_thread_local(ptls, jl_all_tls_states[i]);
mark_roots(ptls);
jl_gc_mark_ptrfree(ptls);
}
// allocator entry points
JL_DLLEXPORT jl_value_t *(jl_gc_alloc)(jl_ptls_t ptls, size_t sz, void *ty)
{
return jl_gc_alloc_(ptls, sz, ty);
}
// Per-thread initialization (when threading is fully implemented)
void jl_mk_thread_heap(jl_ptls_t ptls)
{
jl_thread_heap_t *heap = &ptls->heap;
jl_gc_pool_t *p = heap->norm_pools;
for(int i=0; i < JL_GC_N_POOLS; i++) {
assert((jl_gc_sizeclasses[i] < 16 &&
jl_gc_sizeclasses[i] % sizeof(void*) == 0) ||
(jl_gc_sizeclasses[i] % 16 == 0));
p[i].osize = jl_gc_sizeclasses[i];
p[i].freelist = NULL;
p[i].newpages = NULL;
}
arraylist_new(&heap->weak_refs, 0);
heap->mallocarrays = NULL;
heap->mafreelist = NULL;
heap->big_objects = NULL;
arraylist_new(&heap->rem_bindings, 0);
heap->remset = &heap->_remset[0];
heap->last_remset = &heap->_remset[1];
arraylist_new(heap->remset, 0);
arraylist_new(heap->last_remset, 0);
arraylist_new(&ptls->finalizers, 0);
}
// System-wide initializations
void jl_gc_init(void)
{
jl_gc_init_page();
gc_debug_init();
arraylist_new(&finalizer_list_marked, 0);
arraylist_new(&to_finalize, 0);
gc_num.interval = default_collect_interval;
last_long_collect_interval = default_collect_interval;
gc_num.allocd = -default_collect_interval;
#ifdef _P64
// on a big memory machine, set max_collect_interval to totalmem * nthreads / ncores / 2
size_t maxmem = (uv_get_total_memory() * jl_n_threads) / jl_cpu_cores() / 2;
if (maxmem > max_collect_interval)
max_collect_interval = maxmem;
#endif
}
JL_DLLEXPORT void *jl_gc_counted_malloc(size_t sz)
{
jl_ptls_t ptls = jl_get_ptls_states();
sz += JL_SMALL_BYTE_ALIGNMENT;
maybe_collect(ptls);
gc_num.allocd += sz;
gc_num.malloc++;
void *b = malloc(sz);
if (b == NULL)
jl_throw(jl_memory_exception);
return b;
}
JL_DLLEXPORT void *jl_gc_counted_calloc(size_t nm, size_t sz)
{
jl_ptls_t ptls = jl_get_ptls_states();
nm += JL_SMALL_BYTE_ALIGNMENT;
maybe_collect(ptls);
gc_num.allocd += nm*sz;
gc_num.malloc++;
void *b = calloc(nm, sz);
if (b == NULL)
jl_throw(jl_memory_exception);
return b;
}
JL_DLLEXPORT void jl_gc_counted_free(void *p, size_t sz)
{
free(p);
gc_num.freed += sz + JL_SMALL_BYTE_ALIGNMENT;
gc_num.freecall++;
}
JL_DLLEXPORT void *jl_gc_counted_realloc_with_old_size(void *p, size_t old, size_t sz)
{
jl_ptls_t ptls = jl_get_ptls_states();
old += JL_SMALL_BYTE_ALIGNMENT;
sz += JL_SMALL_BYTE_ALIGNMENT;
maybe_collect(ptls);
if (sz < old)
gc_num.freed += (old - sz);
else
gc_num.allocd += (sz - old);
gc_num.realloc++;
void *b = realloc(p, sz);
if (b == NULL)
jl_throw(jl_memory_exception);
return b;
}
JL_DLLEXPORT void *jl_malloc(size_t sz)
{
int64_t *p = (int64_t *)jl_gc_counted_malloc(sz);
p[0] = sz;
return (void *)(p + 2);
}
JL_DLLEXPORT void *jl_calloc(size_t nm, size_t sz)
{
int64_t *p;
size_t nmsz = nm*sz;
p = (int64_t *)jl_gc_counted_calloc(nmsz, 1);
p[0] = nmsz;
return (void *)(p + 2);
}
JL_DLLEXPORT void jl_free(void *p)
{
if (p != NULL) {
int64_t *pp = (int64_t *)p - 2;
size_t sz = pp[0];
jl_gc_counted_free(pp, sz);
}
}
JL_DLLEXPORT void *jl_realloc(void *p, size_t sz)
{
int64_t *pp;
size_t szold;
if (p == NULL) {
pp = NULL;
szold = 0;
}
else {
pp = (int64_t *)p - 2;
szold = pp[0];
}
int64_t *pnew = (int64_t *)jl_gc_counted_realloc_with_old_size(pp, szold, sz);
pnew[0] = sz;
return (void *)(pnew + 2);
}
JL_DLLEXPORT void *jl_gc_managed_malloc(size_t sz)
{
jl_ptls_t ptls = jl_get_ptls_states();
maybe_collect(ptls);
size_t allocsz = LLT_ALIGN(sz, JL_CACHE_BYTE_ALIGNMENT);
if (allocsz < sz) // overflow in adding offs, size was "negative"
jl_throw(jl_memory_exception);
gc_num.allocd += allocsz;
gc_num.malloc++;
void *b = malloc_cache_align(allocsz);
if (b == NULL)
jl_throw(jl_memory_exception);
return b;
}
static void *gc_managed_realloc_(jl_ptls_t ptls, void *d, size_t sz, size_t oldsz,
int isaligned, jl_value_t *owner, int8_t can_collect)
{
if (can_collect)
maybe_collect(ptls);
size_t allocsz = LLT_ALIGN(sz, JL_CACHE_BYTE_ALIGNMENT);
if (allocsz < sz) // overflow in adding offs, size was "negative"
jl_throw(jl_memory_exception);
if (jl_astaggedvalue(owner)->bits.gc == GC_OLD_MARKED) {
ptls->gc_cache.perm_scanned_bytes += allocsz - oldsz;
live_bytes += allocsz - oldsz;
}
else if (allocsz < oldsz)
gc_num.freed += (oldsz - allocsz);
else
gc_num.allocd += (allocsz - oldsz);
gc_num.realloc++;
void *b;
if (isaligned)
b = realloc_cache_align(d, allocsz, oldsz);
else
b = realloc(d, allocsz);
if (b == NULL)
jl_throw(jl_memory_exception);
return b;
}
JL_DLLEXPORT void *jl_gc_managed_realloc(void *d, size_t sz, size_t oldsz,
int isaligned, jl_value_t *owner)
{
jl_ptls_t ptls = jl_get_ptls_states();
return gc_managed_realloc_(ptls, d, sz, oldsz, isaligned, owner, 1);
}
jl_value_t *jl_gc_realloc_string(jl_value_t *s, size_t sz)
{
size_t len = jl_string_len(s);
if (sz <= len) return s;
jl_taggedvalue_t *v = jl_astaggedvalue(s);
size_t strsz = len + sizeof(size_t) + 1;
if (strsz <= GC_MAX_SZCLASS ||
// TODO: because of issue #17971 we can't resize old objects
gc_marked(v->bits.gc)) {
// pool allocated; can't be grown in place so allocate a new object.
jl_value_t *snew = jl_alloc_string(sz);
memcpy(jl_string_data(snew), jl_string_data(s), len);
return snew;
}
size_t newsz = sz + sizeof(size_t) + 1;
size_t offs = offsetof(bigval_t, header);
size_t allocsz = LLT_ALIGN(newsz + offs, JL_CACHE_BYTE_ALIGNMENT);
if (allocsz < sz) // overflow in adding offs, size was "negative"
jl_throw(jl_memory_exception);
bigval_t *hdr = bigval_header(v);
jl_ptls_t ptls = jl_get_ptls_states();
maybe_collect(ptls); // don't want this to happen during jl_gc_managed_realloc
gc_big_object_unlink(hdr);
// TODO: this is not safe since it frees the old pointer. ideally we'd like
// the old pointer to be left alone if we can't grow in place.
// for now it's up to the caller to make sure there are no references to the
// old pointer.
bigval_t *newbig =
(bigval_t*)gc_managed_realloc_(ptls, hdr, allocsz, LLT_ALIGN(strsz+offs, JL_CACHE_BYTE_ALIGNMENT),
1, s, 0);
newbig->sz = allocsz;
newbig->age = 0;
gc_big_object_link(newbig, &ptls->heap.big_objects);
jl_value_t *snew = jl_valueof(&newbig->header);
*(size_t*)snew = sz;
return snew;
}
// Perm gen allocator
// 2M pool
#define GC_PERM_POOL_SIZE (2 * 1024 * 1024)
// 20k limit for pool allocation. At most 1% fragmentation
#define GC_PERM_POOL_LIMIT (20 * 1024)
jl_mutex_t gc_perm_lock = {0, 0};
static char *gc_perm_pool = NULL;
static size_t gc_perm_size = 0;
// **NOT** a safepoint
void *jl_gc_perm_alloc_nolock(size_t sz)
{
// The caller should have acquired `gc_perm_lock`
#ifndef MEMDEBUG
if (__unlikely(sz > GC_PERM_POOL_LIMIT))
#endif
return malloc(sz);
sz = LLT_ALIGN(sz, JL_SMALL_BYTE_ALIGNMENT);
if (__unlikely(sz > gc_perm_size)) {
#ifdef _OS_WINDOWS_
void *pool = VirtualAlloc(NULL,
GC_PERM_POOL_SIZE + JL_SMALL_BYTE_ALIGNMENT,
MEM_COMMIT, PAGE_READWRITE);
if (__unlikely(pool == NULL))
return NULL;
pool = (void*)LLT_ALIGN((uintptr_t)pool, JL_SMALL_BYTE_ALIGNMENT);
#else
void *pool = mmap(0, GC_PERM_POOL_SIZE, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (__unlikely(pool == MAP_FAILED))
return NULL;
#endif
gc_perm_pool = (char*)pool;
gc_perm_size = GC_PERM_POOL_SIZE;
}
assert(((uintptr_t)gc_perm_pool) % JL_SMALL_BYTE_ALIGNMENT == 0);
void *p = gc_perm_pool;
gc_perm_size -= sz;
gc_perm_pool += sz;
return p;
}
// **NOT** a safepoint
void *jl_gc_perm_alloc(size_t sz)
{
#ifndef MEMDEBUG
if (__unlikely(sz > GC_PERM_POOL_LIMIT))
#endif
return malloc(sz);
JL_LOCK_NOGC(&gc_perm_lock);
void *p = jl_gc_perm_alloc_nolock(sz);
JL_UNLOCK_NOGC(&gc_perm_lock);
return p;
}
JL_DLLEXPORT void jl_gc_add_finalizer(jl_value_t *v, jl_function_t *f)
{
jl_ptls_t ptls = jl_get_ptls_states();
jl_gc_add_finalizer_th(ptls, v, f);
}
JL_DLLEXPORT void jl_finalize(jl_value_t *o)
{
jl_ptls_t ptls = jl_get_ptls_states();
jl_finalize_th(ptls, o);
}
JL_DLLEXPORT jl_weakref_t *jl_gc_new_weakref(jl_value_t *value)
{
jl_ptls_t ptls = jl_get_ptls_states();
return jl_gc_new_weakref_th(ptls, value);
}
JL_DLLEXPORT jl_value_t *jl_gc_allocobj(size_t sz)
{
jl_ptls_t ptls = jl_get_ptls_states();
return jl_gc_alloc(ptls, sz, NULL);
}
JL_DLLEXPORT jl_value_t *jl_gc_alloc_0w(void)
{
jl_ptls_t ptls = jl_get_ptls_states();
return jl_gc_alloc(ptls, 0, NULL);
}
JL_DLLEXPORT jl_value_t *jl_gc_alloc_1w(void)
{
jl_ptls_t ptls = jl_get_ptls_states();
return jl_gc_alloc(ptls, sizeof(void*), NULL);
}
JL_DLLEXPORT jl_value_t *jl_gc_alloc_2w(void)
{
jl_ptls_t ptls = jl_get_ptls_states();
return jl_gc_alloc(ptls, sizeof(void*) * 2, NULL);
}
JL_DLLEXPORT jl_value_t *jl_gc_alloc_3w(void)
{
jl_ptls_t ptls = jl_get_ptls_states();
return jl_gc_alloc(ptls, sizeof(void*) * 3, NULL);
}
#ifdef __cplusplus
}
#endif