julia_threads.h
// This file is a part of Julia. License is MIT: https://julialang.org/license
// Meant to be included in <julia.h>
#ifndef JL_THREADS_H
#define JL_THREADS_H
#include "gc-tls.h"
#include "julia_atomics.h"
#ifndef _OS_WINDOWS_
#include "pthread.h"
#endif
// threading ------------------------------------------------------------------
#ifdef __cplusplus
extern "C" {
#endif
JL_DLLEXPORT int16_t jl_threadid(void);
JL_DLLEXPORT int8_t jl_threadpoolid(int16_t tid) JL_NOTSAFEPOINT;
// JULIA_ENABLE_THREADING may be controlled by altering JULIA_THREADS in Make.user
// When running into scheduler issues, this may help provide information on the
// sequence of events that led to the issue. Normally, it is empty.
//#define JULIA_DEBUG_SLEEPWAKE(x) x
#define JULIA_DEBUG_SLEEPWAKE(x)
// Options for task switching algorithm (in order of preference):
// JL_HAVE_ASM -- mostly setjmp
// JL_HAVE_ASM && JL_HAVE_UNW_CONTEXT -- libunwind-based
// JL_HAVE_UNW_CONTEXT -- libunwind-based
// JL_HAVE_UCONTEXT -- posix standard API, requires syscall for resume
#ifdef _OS_WINDOWS_
#define JL_HAVE_UCONTEXT
typedef win32_ucontext_t jl_stack_context_t;
typedef jl_stack_context_t _jl_ucontext_t;
#elif defined(_OS_OPENBSD_)
#define JL_HAVE_UNW_CONTEXT
#define UNW_LOCAL_ONLY
#include <libunwind.h>
typedef unw_context_t _jl_ucontext_t;
typedef struct {
jl_jmp_buf uc_mcontext;
} jl_stack_context_t;
#else
typedef struct {
jl_jmp_buf uc_mcontext;
} jl_stack_context_t;
#if !defined(JL_HAVE_UCONTEXT) && \
!defined(JL_HAVE_ASM) && \
!defined(JL_HAVE_UNW_CONTEXT)
#if (defined(_CPU_X86_64_) || defined(_CPU_X86_) || defined(_CPU_AARCH64_) || \
defined(_CPU_ARM_) || defined(_CPU_PPC64_))
#define JL_HAVE_ASM
#endif
#if 0
// very slow, but more debugging
//#elif defined(_OS_DARWIN_)
//#define JL_HAVE_UNW_CONTEXT
//#elif defined(_OS_LINUX_)
//#define JL_HAVE_UNW_CONTEXT
#elif !defined(JL_HAVE_ASM)
#define JL_HAVE_UNW_CONTEXT // optimistically?
#endif
#endif
#if !defined(JL_HAVE_UNW_CONTEXT) && defined(JL_HAVE_ASM)
typedef jl_stack_context_t _jl_ucontext_t;
#endif
#pragma GCC visibility push(default)
#if defined(JL_HAVE_UNW_CONTEXT)
#define UNW_LOCAL_ONLY
#include <libunwind.h>
typedef unw_context_t _jl_ucontext_t;
#endif
#if defined(JL_HAVE_UCONTEXT)
#include <ucontext.h>
typedef ucontext_t _jl_ucontext_t;
#endif
#pragma GCC visibility pop
#endif
typedef struct {
union {
_jl_ucontext_t ctx;
jl_stack_context_t copy_ctx;
};
#if defined(_COMPILER_TSAN_ENABLED_)
void *tsan_state;
#endif
#if defined(_COMPILER_ASAN_ENABLED_)
void *asan_fake_stack;
#endif
} jl_ucontext_t;
// handle to reference an OS thread
#ifdef _OS_WINDOWS_
typedef HANDLE jl_thread_t;
#else
typedef pthread_t jl_thread_t;
#endif
struct _jl_task_t;
// Recursive spin lock
typedef struct {
_Atomic(struct _jl_task_t*) owner;
uint32_t count;
} jl_mutex_t;
struct _jl_bt_element_t;
// This includes all the thread local states we care about for a thread.
// Changes to TLS field types must be reflected in codegen.
#define JL_MAX_BT_SIZE 80000
typedef struct _jl_tls_states_t {
int16_t tid;
int8_t threadpoolid;
uint64_t rngseed;
_Atomic(volatile size_t *) safepoint; // may be changed to the suspend page by any thread
_Atomic(int8_t) sleep_check_state; // read/write from foreign threads
// Whether it is safe to execute GC at the same time.
#define JL_GC_STATE_UNSAFE 0
// gc_state = 0 means the thread is running Julia code and is not
// safe to run concurrently to the GC
#define JL_GC_STATE_WAITING 1
// gc_state = 1 means the thread is doing GC or is waiting for the GC to
// finish.
#define JL_GC_STATE_SAFE 2
// gc_state = 2 means the thread is running unmanaged code that can be
// execute at the same time with the GC.
#define JL_GC_PARALLEL_COLLECTOR_THREAD 3
// gc_state = 3 means the thread is a parallel collector thread (i.e. never runs Julia code)
#define JL_GC_CONCURRENT_COLLECTOR_THREAD 4
// gc_state = 4 means the thread is a concurrent collector thread (background sweeper thread that never runs Julia code)
_Atomic(int8_t) gc_state; // read from foreign threads
// execution of certain certain impure
// statements is prohibited from certain
// callbacks (such as generated functions)
// as it may make compilation undecidable
int16_t in_pure_callback;
int16_t in_finalizer;
int16_t disable_gc;
// Counter to disable finalizer **on the current thread**
int finalizers_inhibited;
jl_gc_tls_states_t gc_tls; // this is very large, and the offset of the first member is baked into codegen
volatile sig_atomic_t defer_signal;
_Atomic(struct _jl_task_t*) current_task;
struct _jl_task_t *next_task;
struct _jl_task_t *previous_task;
struct _jl_task_t *root_task;
struct _jl_timing_block_t *timing_stack;
void *stackbase;
size_t stacksize;
union {
_jl_ucontext_t base_ctx; // base context of stack
// This hack is needed to support always_copy_stacks:
jl_stack_context_t copy_stack_ctx;
};
// Temp storage for exception thrown in signal handler. Not rooted.
struct _jl_value_t *sig_exception;
// Temporary backtrace buffer. Scanned for gc roots when bt_size > 0.
struct _jl_bt_element_t *bt_data; // JL_MAX_BT_SIZE + 1 elements long
size_t bt_size; // Size for backtrace in transit in bt_data
// Temporary backtrace buffer used only for allocations profiler.
struct _jl_bt_element_t *profiling_bt_buffer;
// Atomically set by the sender, reset by the handler.
volatile _Atomic(sig_atomic_t) signal_request; // TODO: no actual reason for this to be _Atomic
// Allow the sigint to be raised asynchronously
// this is limited to the few places we do synchronous IO
// we can make this more general (similar to defer_signal) if necessary
volatile sig_atomic_t io_wait;
#ifdef _OS_WINDOWS_
int needs_resetstkoflw;
#else
void *signal_stack;
size_t signal_stack_size;
#endif
jl_thread_t system_id;
_Atomic(int16_t) suspend_count;
arraylist_t finalizers;
// Saved exception for previous *external* API call or NULL if cleared.
// Access via jl_exception_occurred().
struct _jl_value_t *previous_exception;
// currently-held locks, to be released when an exception is thrown
small_arraylist_t locks;
size_t engine_nqueued;
JULIA_DEBUG_SLEEPWAKE(
uint64_t uv_run_enter;
uint64_t uv_run_leave;
uint64_t sleep_enter;
uint64_t sleep_leave;
)
// some hidden state (usually just because we don't have the type's size declaration)
#ifdef JL_LIBRARY_EXPORTS
uv_mutex_t sleep_lock;
uv_cond_t wake_signal;
#endif
} jl_tls_states_t;
#ifndef JL_LIBRARY_EXPORTS
// deprecated (only for external consumers)
JL_DLLEXPORT void *jl_get_ptls_states(void);
#endif
// Update codegen version in `ccall.cpp` after changing either `pause` or `wake`
#ifdef __MIC__
# define jl_cpu_pause() _mm_delay_64(100)
# define jl_cpu_suspend() _mm_delay_64(100)
# define jl_cpu_wake() ((void)0)
# define JL_CPU_WAKE_NOOP 1
#elif defined(_CPU_X86_64_) || defined(_CPU_X86_) /* !__MIC__ */
# define jl_cpu_pause() _mm_pause()
# define jl_cpu_suspend() _mm_pause()
# define jl_cpu_wake() ((void)0)
# define JL_CPU_WAKE_NOOP 1
#elif defined(_CPU_AARCH64_) || (defined(_CPU_ARM_) && __ARM_ARCH >= 7)
# define jl_cpu_pause() __asm__ volatile ("isb" ::: "memory")
# define jl_cpu_suspend() __asm__ volatile ("wfe" ::: "memory")
# define jl_cpu_wake() __asm__ volatile ("sev" ::: "memory")
# define JL_CPU_WAKE_NOOP 0
#else
# define jl_cpu_pause() ((void)0)
# define jl_cpu_suspend() ((void)0)
# define jl_cpu_wake() ((void)0)
# define JL_CPU_WAKE_NOOP 1
#endif
JL_DLLEXPORT void (jl_cpu_pause)(void);
JL_DLLEXPORT void (jl_cpu_suspend)(void);
JL_DLLEXPORT void (jl_cpu_wake)(void);
#ifdef __clang_gcanalyzer__
// Note that the sigint safepoint can also trigger GC, albeit less likely
void jl_gc_safepoint_(jl_ptls_t tls);
void jl_sigint_safepoint(jl_ptls_t tls);
#else
// gc safepoint and gc states
// This triggers a SegFault when we are in GC
// Assign it to a variable to make sure the compiler emit the load
// and to avoid Clang warning for -Wunused-volatile-lvalue
#define jl_gc_safepoint_(ptls) do { \
jl_signal_fence(); \
size_t safepoint_load = jl_atomic_load_relaxed(&ptls->safepoint)[0]; \
jl_signal_fence(); \
(void)safepoint_load; \
} while (0)
#define jl_sigint_safepoint(ptls) do { \
jl_signal_fence(); \
size_t safepoint_load = jl_atomic_load_relaxed(&ptls->safepoint)[-1]; \
jl_signal_fence(); \
(void)safepoint_load; \
} while (0)
#endif
STATIC_INLINE int8_t jl_gc_state_set(jl_ptls_t ptls, int8_t state,
int8_t old_state)
{
assert(old_state != JL_GC_PARALLEL_COLLECTOR_THREAD);
assert(old_state != JL_GC_CONCURRENT_COLLECTOR_THREAD);
jl_atomic_store_release(&ptls->gc_state, state);
if (state == JL_GC_STATE_UNSAFE || old_state == JL_GC_STATE_UNSAFE)
jl_gc_safepoint_(ptls);
return old_state;
}
STATIC_INLINE int8_t jl_gc_state_save_and_set(jl_ptls_t ptls,
int8_t state)
{
return jl_gc_state_set(ptls, state, jl_atomic_load_relaxed(&ptls->gc_state));
}
#ifdef __clang_gcanalyzer__
// these might not be a safepoint (if they are no-op safe=>safe transitions), but we have to assume it could be (statically)
// however mark a delineated region in which safepoints would be not permissible
int8_t jl_gc_unsafe_enter(jl_ptls_t ptls) JL_NOTSAFEPOINT_LEAVE;
void jl_gc_unsafe_leave(jl_ptls_t ptls, int8_t state) JL_NOTSAFEPOINT_ENTER;
int8_t jl_gc_safe_enter(jl_ptls_t ptls) JL_NOTSAFEPOINT_ENTER;
void jl_gc_safe_leave(jl_ptls_t ptls, int8_t state) JL_NOTSAFEPOINT_LEAVE;
#else
#define jl_gc_unsafe_enter(ptls) jl_gc_state_save_and_set(ptls, JL_GC_STATE_UNSAFE)
#define jl_gc_unsafe_leave(ptls, state) ((void)jl_gc_state_set(ptls, (state), JL_GC_STATE_UNSAFE))
#define jl_gc_safe_enter(ptls) jl_gc_state_save_and_set(ptls, JL_GC_STATE_SAFE)
#define jl_gc_safe_leave(ptls, state) ((void)jl_gc_state_set(ptls, (state), JL_GC_STATE_SAFE))
#endif
JL_DLLEXPORT void jl_gc_enable_finalizers(struct _jl_task_t *ct, int on);
JL_DLLEXPORT void jl_gc_disable_finalizers_internal(void) JL_NOTSAFEPOINT;
JL_DLLEXPORT void jl_gc_enable_finalizers_internal(void);
JL_DLLEXPORT void jl_gc_run_pending_finalizers(struct _jl_task_t *ct);
extern JL_DLLEXPORT _Atomic(int) jl_gc_have_pending_finalizers;
JL_DLLEXPORT int8_t jl_gc_is_in_finalizer(void) JL_NOTSAFEPOINT;
JL_DLLEXPORT void jl_wakeup_thread(int16_t tid);
JL_DLLEXPORT int jl_getaffinity(int16_t tid, char *mask, int cpumasksize);
JL_DLLEXPORT int jl_setaffinity(int16_t tid, char *mask, int cpumasksize);
#ifdef __cplusplus
}
#endif
#endif
