Revision aed7abbcca7574ed438c3b22e27db9bf249e8de3 authored by Xin Tong on 18 May 2018, 00:49:06 UTC, committed by Facebook Github Bot on 18 May 2018, 00:57:48 UTC
Summary: Running. TEST_TMPDIR=/dev/shm ./buck-out/gen/rocks/tools/rocks_db_bench --benchmarks=readwhilewriting --num=5000000 -benchmark_write_rate_limit=2000000 --threads=32 Collected esan data and reorder field. Accesses to 4th and 6th fields take majority of the access. Group them. Overall, this struct takes 10%+ of the total accesses in the program. (637773011/6107964986) ==2433831== class rocksdb::InlineSkipList ==2433831== size = 48, count = 637773011, ratio = 112412, array access = 0 ==2433831== # 0: offset = 0, size = 2, count = 455137, type = i16 ==2433831== # 1: offset = 2, size = 2, count = 6, type = i16 ==2433831== # 2: offset = 4, size = 4, count = 182303, type = i32 ==2433831== # 3: offset = 8, size = 8, count = 263953900, type = %"class.rocksdb::MemTableRep::KeyComparator"* ==2433831== # 4: offset = 16, size = 8, count = 136409, type = %"class.rocksdb::Allocator"* ==2433831== # 5: offset = 24, size = 8, count = 366628820, type = %"struct.rocksdb::InlineSkipList<const rocksdb::MemTableRep::KeyComparator &>::Node"* ==2433831== # 6: offset = 32, size = 4, count = 6280031, type = %"struct.std::atomic" = type { %"struct.std::__atomic_base" } ==2433831== # 7: offset = 40, size = 8, count = 136405, type = %"struct.rocksdb::InlineSkipList<const rocksdb::MemTableRep::KeyComparator &>::Splice"* ==2433831==EfficiencySanitizer: total struct field access count = 6107964986 Before re-ordering [trentxintong@devbig460.frc2 ~/fbsource/fbcode]$ fgrep readwhilewriting without-ro.log readwhilewriting : 0.036 micros/op 27545605 ops/sec; 26.8 MB/s (45954 of 5000000 found) readwhilewriting : 0.036 micros/op 28024240 ops/sec; 27.2 MB/s (43158 of 5000000 found) readwhilewriting : 0.037 micros/op 27345145 ops/sec; 27.1 MB/s (46725 of 5000000 found) readwhilewriting : 0.037 micros/op 27072588 ops/sec; 27.3 MB/s (42605 of 5000000 found) readwhilewriting : 0.034 micros/op 29578781 ops/sec; 28.3 MB/s (44294 of 5000000 found) readwhilewriting : 0.035 micros/op 28528304 ops/sec; 27.7 MB/s (44176 of 5000000 found) readwhilewriting : 0.037 micros/op 27075497 ops/sec; 26.5 MB/s (43763 of 5000000 found) readwhilewriting : 0.036 micros/op 28024117 ops/sec; 27.1 MB/s (40622 of 5000000 found) readwhilewriting : 0.037 micros/op 27078709 ops/sec; 27.6 MB/s (47774 of 5000000 found) readwhilewriting : 0.034 micros/op 29020689 ops/sec; 28.1 MB/s (45066 of 5000000 found) AVERAGE()=27.37 MB/s After re-ordering [trentxintong@devbig460.frc2 ~/fbsource/fbcode]$ fgrep readwhilewriting ro.log readwhilewriting : 0.036 micros/op 27542409 ops/sec; 27.7 MB/s (46163 of 5000000 found) readwhilewriting : 0.036 micros/op 28021148 ops/sec; 28.2 MB/s (46155 of 5000000 found) readwhilewriting : 0.036 micros/op 28021035 ops/sec; 27.3 MB/s (44039 of 5000000 found) readwhilewriting : 0.036 micros/op 27538659 ops/sec; 27.5 MB/s (46781 of 5000000 found) readwhilewriting : 0.036 micros/op 28028604 ops/sec; 27.6 MB/s (44689 of 5000000 found) readwhilewriting : 0.036 micros/op 27541452 ops/sec; 27.3 MB/s (43156 of 5000000 found) readwhilewriting : 0.034 micros/op 29041338 ops/sec; 28.8 MB/s (44895 of 5000000 found) readwhilewriting : 0.036 micros/op 27784974 ops/sec; 26.3 MB/s (39963 of 5000000 found) readwhilewriting : 0.036 micros/op 27538892 ops/sec; 28.1 MB/s (46570 of 5000000 found) readwhilewriting : 0.038 micros/op 26622473 ops/sec; 27.0 MB/s (43236 of 5000000 found) AVERAGE()=27.58 MB/s Closes https://github.com/facebook/rocksdb/pull/3855 Reviewed By: siying Differential Revision: D8048781 Pulled By: trentxintong fbshipit-source-id: bc9807a9845e2a92cb171ce1ecb5a2c8a51f1481
1 parent fa43948
optimistic_transaction_example.cc
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#ifndef ROCKSDB_LITE
#include "rocksdb/db.h"
#include "rocksdb/options.h"
#include "rocksdb/slice.h"
#include "rocksdb/utilities/transaction.h"
#include "rocksdb/utilities/optimistic_transaction_db.h"
using namespace rocksdb;
std::string kDBPath = "/tmp/rocksdb_transaction_example";
int main() {
// open DB
Options options;
options.create_if_missing = true;
DB* db;
OptimisticTransactionDB* txn_db;
Status s = OptimisticTransactionDB::Open(options, kDBPath, &txn_db);
assert(s.ok());
db = txn_db->GetBaseDB();
WriteOptions write_options;
ReadOptions read_options;
OptimisticTransactionOptions txn_options;
std::string value;
////////////////////////////////////////////////////////
//
// Simple OptimisticTransaction Example ("Read Committed")
//
////////////////////////////////////////////////////////
// Start a transaction
Transaction* txn = txn_db->BeginTransaction(write_options);
assert(txn);
// Read a key in this transaction
s = txn->Get(read_options, "abc", &value);
assert(s.IsNotFound());
// Write a key in this transaction
txn->Put("abc", "def");
// Read a key OUTSIDE this transaction. Does not affect txn.
s = db->Get(read_options, "abc", &value);
// Write a key OUTSIDE of this transaction.
// Does not affect txn since this is an unrelated key. If we wrote key 'abc'
// here, the transaction would fail to commit.
s = db->Put(write_options, "xyz", "zzz");
// Commit transaction
s = txn->Commit();
assert(s.ok());
delete txn;
////////////////////////////////////////////////////////
//
// "Repeatable Read" (Snapshot Isolation) Example
// -- Using a single Snapshot
//
////////////////////////////////////////////////////////
// Set a snapshot at start of transaction by setting set_snapshot=true
txn_options.set_snapshot = true;
txn = txn_db->BeginTransaction(write_options, txn_options);
const Snapshot* snapshot = txn->GetSnapshot();
// Write a key OUTSIDE of transaction
db->Put(write_options, "abc", "xyz");
// Read a key using the snapshot
read_options.snapshot = snapshot;
s = txn->GetForUpdate(read_options, "abc", &value);
assert(value == "def");
// Attempt to commit transaction
s = txn->Commit();
// Transaction could not commit since the write outside of the txn conflicted
// with the read!
assert(s.IsBusy());
delete txn;
// Clear snapshot from read options since it is no longer valid
read_options.snapshot = nullptr;
snapshot = nullptr;
////////////////////////////////////////////////////////
//
// "Read Committed" (Monotonic Atomic Views) Example
// --Using multiple Snapshots
//
////////////////////////////////////////////////////////
// In this example, we set the snapshot multiple times. This is probably
// only necessary if you have very strict isolation requirements to
// implement.
// Set a snapshot at start of transaction
txn_options.set_snapshot = true;
txn = txn_db->BeginTransaction(write_options, txn_options);
// Do some reads and writes to key "x"
read_options.snapshot = db->GetSnapshot();
s = txn->Get(read_options, "x", &value);
txn->Put("x", "x");
// Do a write outside of the transaction to key "y"
s = db->Put(write_options, "y", "y");
// Set a new snapshot in the transaction
txn->SetSnapshot();
read_options.snapshot = db->GetSnapshot();
// Do some reads and writes to key "y"
s = txn->GetForUpdate(read_options, "y", &value);
txn->Put("y", "y");
// Commit. Since the snapshot was advanced, the write done outside of the
// transaction does not prevent this transaction from Committing.
s = txn->Commit();
assert(s.ok());
delete txn;
// Clear snapshot from read options since it is no longer valid
read_options.snapshot = nullptr;
// Cleanup
delete txn_db;
DestroyDB(kDBPath, options);
return 0;
}
#endif // ROCKSDB_LITE
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