mirror of
https://github.com/facebook/rocksdb.git
synced 2024-11-27 02:44:18 +00:00
ec7a944360
Summary: We occasionally get write stalls (>1s Write() calls) on HDD under read load. The following timers explain almost all of the stalls: - perf_context.db_mutex_lock_nanos - perf_context.db_condition_wait_nanos - iostats_context.open_time - iostats_context.allocate_time - iostats_context.write_time - iostats_context.range_sync_time - iostats_context.logger_time In my experiments each of these occasionally takes >1s on write path under some workload. There are rare cases when Write() takes long but none of these takes long. Test Plan: Added code to our application to write the listed timings to log for slow writes. They usually add up to almost exactly the time Write() call took. Reviewers: rven, yhchiang, sdong Reviewed By: sdong Subscribers: march, dhruba, tnovak Differential Revision: https://reviews.facebook.net/D39177
44 lines
1.1 KiB
C++
44 lines
1.1 KiB
C++
// Copyright (c) 2014, Facebook, Inc. All rights reserved.
|
|
// This source code is licensed under the BSD-style license found in the
|
|
// LICENSE file in the root directory of this source tree. An additional grant
|
|
// of patent rights can be found in the PATENTS file in the same directory.
|
|
|
|
#include <sstream>
|
|
#include "rocksdb/env.h"
|
|
#include "util/iostats_context_imp.h"
|
|
|
|
namespace rocksdb {
|
|
|
|
#ifndef IOS_CROSS_COMPILE
|
|
__thread IOStatsContext iostats_context;
|
|
#endif // IOS_CROSS_COMPILE
|
|
|
|
void IOStatsContext::Reset() {
|
|
thread_pool_id = Env::Priority::TOTAL;
|
|
bytes_read = 0;
|
|
bytes_written = 0;
|
|
open_nanos = 0;
|
|
allocate_nanos = 0;
|
|
write_nanos = 0;
|
|
range_sync_nanos = 0;
|
|
logger_nanos = 0;
|
|
}
|
|
|
|
#define OUTPUT(counter) #counter << " = " << counter << ", "
|
|
|
|
std::string IOStatsContext::ToString() const {
|
|
std::ostringstream ss;
|
|
ss << OUTPUT(thread_pool_id)
|
|
<< OUTPUT(bytes_read)
|
|
<< OUTPUT(bytes_written)
|
|
<< OUTPUT(open_nanos)
|
|
<< OUTPUT(allocate_nanos)
|
|
<< OUTPUT(write_nanos)
|
|
<< OUTPUT(range_sync_nanos)
|
|
<< OUTPUT(logger_nanos);
|
|
|
|
return ss.str();
|
|
}
|
|
|
|
} // namespace rocksdb
|