rocksdb/db/periodic_work_scheduler.cc
Andrew Kryczka 1e00909730 Periodically flush info log out of application buffer (#7488)
Summary:
This PR schedules a background thread (shared across all DB instances)
to flush info log every ten seconds. This improves debuggability in case
of RocksDB hanging since it ensures the log messages leading up to the hang
will eventually become visible in the log.

The bulk of this PR is moving monitoring/stats_dump_scheduler* to db/periodic_work_scheduler*
and making the corresponding name changes since now the scheduler handles info
log flushing, not just stats dumping.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7488

Reviewed By: riversand963

Differential Revision: D24065165

Pulled By: ajkr

fbshipit-source-id: 339c47a0ff43b79fdbd055fbd9fefbb6f9d8d3b5
2020-10-01 19:14:14 -07:00

110 lines
3.7 KiB
C++

// 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).
#include "db/periodic_work_scheduler.h"
#include "db/db_impl/db_impl.h"
#include "util/cast_util.h"
#ifndef ROCKSDB_LITE
namespace ROCKSDB_NAMESPACE {
PeriodicWorkScheduler::PeriodicWorkScheduler(Env* env) {
timer = std::unique_ptr<Timer>(new Timer(env));
}
void PeriodicWorkScheduler::Register(DBImpl* dbi,
unsigned int stats_dump_period_sec,
unsigned int stats_persist_period_sec) {
static std::atomic<uint64_t> initial_delay(0);
timer->Start();
if (stats_dump_period_sec > 0) {
timer->Add([dbi]() { dbi->DumpStats(); }, GetTaskName(dbi, "dump_st"),
initial_delay.fetch_add(1) %
static_cast<uint64_t>(stats_dump_period_sec) *
kMicrosInSecond,
static_cast<uint64_t>(stats_dump_period_sec) * kMicrosInSecond);
}
if (stats_persist_period_sec > 0) {
timer->Add(
[dbi]() { dbi->PersistStats(); }, GetTaskName(dbi, "pst_st"),
initial_delay.fetch_add(1) %
static_cast<uint64_t>(stats_persist_period_sec) * kMicrosInSecond,
static_cast<uint64_t>(stats_persist_period_sec) * kMicrosInSecond);
}
timer->Add([dbi]() { dbi->FlushInfoLog(); },
GetTaskName(dbi, "flush_info_log"),
initial_delay.fetch_add(1) % kDefaultFlushInfoLogPeriodSec *
kMicrosInSecond,
kDefaultFlushInfoLogPeriodSec * kMicrosInSecond);
}
void PeriodicWorkScheduler::Unregister(DBImpl* dbi) {
timer->Cancel(GetTaskName(dbi, "dump_st"));
timer->Cancel(GetTaskName(dbi, "pst_st"));
timer->Cancel(GetTaskName(dbi, "flush_info_log"));
if (!timer->HasPendingTask()) {
timer->Shutdown();
}
}
PeriodicWorkScheduler* PeriodicWorkScheduler::Default() {
// Always use the default Env for the scheduler, as we only use the NowMicros
// which is the same for all env.
// The Env could only be overridden in test.
static PeriodicWorkScheduler scheduler(Env::Default());
return &scheduler;
}
std::string PeriodicWorkScheduler::GetTaskName(DBImpl* dbi,
const std::string& func_name) {
std::string db_session_id;
// TODO: Should this error be ignored?
dbi->GetDbSessionId(db_session_id).PermitUncheckedError();
return db_session_id + ":" + func_name;
}
#ifndef NDEBUG
// Get the static scheduler. For a new env, it needs to re-create the internal
// timer, so only re-create it when there's no running task. Otherwise, return
// the existing scheduler. Which means if the unittest needs to update MockEnv,
// Close all db instances and then re-open them.
PeriodicWorkTestScheduler* PeriodicWorkTestScheduler::Default(Env* env) {
static PeriodicWorkTestScheduler scheduler(env);
static port::Mutex mutex;
{
MutexLock l(&mutex);
if (scheduler.timer.get() != nullptr &&
scheduler.timer->TEST_GetPendingTaskNum() == 0) {
scheduler.timer->Shutdown();
scheduler.timer.reset(new Timer(env));
}
}
return &scheduler;
}
void PeriodicWorkTestScheduler::TEST_WaitForRun(
std::function<void()> callback) const {
if (timer != nullptr) {
timer->TEST_WaitForRun(callback);
}
}
size_t PeriodicWorkTestScheduler::TEST_GetValidTaskNum() const {
if (timer != nullptr) {
return timer->TEST_GetPendingTaskNum();
}
return 0;
}
PeriodicWorkTestScheduler::PeriodicWorkTestScheduler(Env* env)
: PeriodicWorkScheduler(env) {}
#endif // !NDEBUG
} // namespace ROCKSDB_NAMESPACE
#endif // ROCKSDB_LITE