Avoid updating option if there's no value updated (#8518)

Summary:
Try avoid expensive updating options operation if
`SetDBOptions()` does not change any option value.
Skip updating is not guaranteed, for example, changing `bytes_per_sync`
to `0` may still trigger updating, as the value could be sanitized.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8518

Test Plan: added unittest

Reviewed By: riversand963

Differential Revision: D29672639

Pulled By: jay-zhuang

fbshipit-source-id: b7931de62ceea6f1bdff0d1209adf1197d3ed1f4
main
Jay Zhuang 3 years ago committed by Facebook GitHub Bot
parent 6b4cdacf41
commit 42eaa45c1b
  1. 4
      HISTORY.md
  2. 12
      db/db_impl/db_impl.cc
  3. 60
      db/db_options_test.cc
  4. 9
      options/db_options.cc
  5. 3
      options/db_options.h

@ -21,6 +21,10 @@
### Public API change
* Added APIs to the Customizable class to allow developers to create their own Customizable classes. Created the utilities/customizable_util.h file to contain helper methods for developing new Customizable classes.
* Change signature of SecondaryCache::Name(). Make SecondaryCache customizable and add SecondaryCache::CreateFromString method.
### Performance Improvements
* Try to avoid updating DBOptions if `SetDBOptions()` does not change any option value.
## 6.22.0 (2021-06-18)
### Behavior Changes
* Added two additional tickers, MEMTABLE_PAYLOAD_BYTES_AT_FLUSH and MEMTABLE_GARBAGE_BYTES_AT_FLUSH. These stats can be used to estimate the ratio of "garbage" (outdated) bytes in the memtable that are discarded at flush time.

@ -1136,9 +1136,19 @@ Status DBImpl::SetDBOptions(
InstrumentedMutexLock l(&mutex_);
s = GetMutableDBOptionsFromStrings(mutable_db_options_, options_map,
&new_options);
if (new_options.bytes_per_sync == 0) {
new_options.bytes_per_sync = 1024 * 1024;
}
if (MutableDBOptionsAreEqual(mutable_db_options_, new_options)) {
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"SetDBOptions(), input option value is not changed, "
"skipping updating.");
persist_options_status.PermitUncheckedError();
return s;
}
DBOptions new_db_options =
BuildDBOptions(immutable_db_options_, new_options);
if (s.ok()) {
@ -4194,6 +4204,8 @@ Status DBImpl::WriteOptionsFile(bool need_mutex_lock,
TEST_SYNC_POINT("DBImpl::WriteOptionsFile:1");
TEST_SYNC_POINT("DBImpl::WriteOptionsFile:2");
TEST_SYNC_POINT_CALLBACK("DBImpl::WriteOptionsFile:PersistOptions",
&db_options);
std::string file_name =
TempOptionsFileName(GetName(), versions_->NewFileNumber());

@ -98,6 +98,66 @@ TEST_F(DBOptionsTest, ImmutableTrackAndVerifyWalsInManifest) {
// RocksDB lite don't support dynamic options.
#ifndef ROCKSDB_LITE
TEST_F(DBOptionsTest, AvoidUpdatingOptions) {
Options options;
options.env = env_;
options.max_background_jobs = 4;
options.delayed_write_rate = 1024;
Reopen(options);
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearAllCallBacks();
bool is_changed_stats = false;
SyncPoint::GetInstance()->SetCallBack(
"DBImpl::WriteOptionsFile:PersistOptions", [&](void* /*arg*/) {
ASSERT_FALSE(is_changed_stats); // should only save options file once
is_changed_stats = true;
});
SyncPoint::GetInstance()->EnableProcessing();
// helper function to check the status and reset after each check
auto is_changed = [&] {
bool ret = is_changed_stats;
is_changed_stats = false;
return ret;
};
// without changing the value, but it's sanitized to a different value
ASSERT_OK(dbfull()->SetDBOptions({{"bytes_per_sync", "0"}}));
ASSERT_TRUE(is_changed());
// without changing the value
ASSERT_OK(dbfull()->SetDBOptions({{"max_background_jobs", "4"}}));
ASSERT_FALSE(is_changed());
// changing the value
ASSERT_OK(dbfull()->SetDBOptions({{"bytes_per_sync", "123"}}));
ASSERT_TRUE(is_changed());
// update again
ASSERT_OK(dbfull()->SetDBOptions({{"bytes_per_sync", "123"}}));
ASSERT_FALSE(is_changed());
// without changing a default value
ASSERT_OK(dbfull()->SetDBOptions({{"strict_bytes_per_sync", "false"}}));
ASSERT_FALSE(is_changed());
// now change
ASSERT_OK(dbfull()->SetDBOptions({{"strict_bytes_per_sync", "true"}}));
ASSERT_TRUE(is_changed());
// multiple values without change
ASSERT_OK(dbfull()->SetDBOptions(
{{"max_total_wal_size", "0"}, {"stats_dump_period_sec", "600"}}));
ASSERT_FALSE(is_changed());
// multiple values with change
ASSERT_OK(dbfull()->SetDBOptions(
{{"max_open_files", "100"}, {"stats_dump_period_sec", "600"}}));
ASSERT_TRUE(is_changed());
}
TEST_F(DBOptionsTest, GetLatestDBOptions) {
// GetOptions should be able to get latest option changed by SetOptions.
Options options;

@ -872,6 +872,15 @@ Status GetMutableDBOptionsFromStrings(
return s;
}
bool MutableDBOptionsAreEqual(const MutableDBOptions& this_options,
const MutableDBOptions& that_options) {
ConfigOptions config_options;
std::string mismatch;
return OptionTypeInfo::StructsAreEqual(
config_options, "MutableDBOptions", &db_mutable_options_type_info,
"MutableDBOptions", &this_options, &that_options, &mismatch);
}
Status GetStringFromMutableDBOptions(const ConfigOptions& config_options,
const MutableDBOptions& mutable_opts,
std::string* opt_string) {

@ -141,6 +141,9 @@ Status GetMutableDBOptionsFromStrings(
const MutableDBOptions& base_options,
const std::unordered_map<std::string, std::string>& options_map,
MutableDBOptions* new_options);
bool MutableDBOptionsAreEqual(const MutableDBOptions& this_options,
const MutableDBOptions& that_options);
#endif // ROCKSDB_LITE
} // namespace ROCKSDB_NAMESPACE

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