rocksdb/db/db_statistics_test.cc
Yanqin Jin ab202e8d72 Add a new stats level to exclude tickers (#7329)
Summary:
Currently, application may pass a statistics object to db but later
wants to reduce stats tracking overhead by setting stats level to
kExceptHistogramOrTimers (the current lowest level). Tickers will still
be incremented, causing up to 1% CPU. We can add a new lowest stats
level `kExceptTickers` to disable ticker incrementing as well, thus
reducing CPU cycles spent on tickers.

Test Plan (devserver):
```
make check
make clean
DEBUG_LEVEL=0 make db_bench
./db_bench -perf_level=1 -stats_level=0 -statistics -benchmarks=fillseq,readrandom -duration=120
```

Measure CPU util (%) before and after change:
CPU util by rocksdb::RecordTick: 1.1 vs (<0.1)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7329

Reviewed By: pdillinger

Differential Revision: D23434014

Pulled By: riversand963

fbshipit-source-id: 72ff0f02a192ac476d4b0044b9f37fd4a22ff0d4
2020-09-04 23:25:03 -07:00

165 lines
5.8 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 <string>
#include "db/db_test_util.h"
#include "monitoring/thread_status_util.h"
#include "port/stack_trace.h"
#include "rocksdb/statistics.h"
#include "util/random.h"
namespace ROCKSDB_NAMESPACE {
class DBStatisticsTest : public DBTestBase {
public:
DBStatisticsTest()
: DBTestBase("/db_statistics_test", /*env_do_fsync=*/true) {}
};
TEST_F(DBStatisticsTest, CompressionStatsTest) {
CompressionType type;
if (Snappy_Supported()) {
type = kSnappyCompression;
fprintf(stderr, "using snappy\n");
} else if (Zlib_Supported()) {
type = kZlibCompression;
fprintf(stderr, "using zlib\n");
} else if (BZip2_Supported()) {
type = kBZip2Compression;
fprintf(stderr, "using bzip2\n");
} else if (LZ4_Supported()) {
type = kLZ4Compression;
fprintf(stderr, "using lz4\n");
} else if (XPRESS_Supported()) {
type = kXpressCompression;
fprintf(stderr, "using xpress\n");
} else if (ZSTD_Supported()) {
type = kZSTD;
fprintf(stderr, "using ZSTD\n");
} else {
fprintf(stderr, "skipping test, compression disabled\n");
return;
}
Options options = CurrentOptions();
options.compression = type;
options.statistics = ROCKSDB_NAMESPACE::CreateDBStatistics();
options.statistics->set_stats_level(StatsLevel::kExceptTimeForMutex);
DestroyAndReopen(options);
int kNumKeysWritten = 100000;
// Check that compressions occur and are counted when compression is turned on
Random rnd(301);
for (int i = 0; i < kNumKeysWritten; ++i) {
// compressible string
ASSERT_OK(Put(Key(i), rnd.RandomString(128) + std::string(128, 'a')));
}
ASSERT_OK(Flush());
ASSERT_GT(options.statistics->getTickerCount(NUMBER_BLOCK_COMPRESSED), 0);
for (int i = 0; i < kNumKeysWritten; ++i) {
auto r = Get(Key(i));
}
ASSERT_GT(options.statistics->getTickerCount(NUMBER_BLOCK_DECOMPRESSED), 0);
options.compression = kNoCompression;
DestroyAndReopen(options);
uint64_t currentCompressions =
options.statistics->getTickerCount(NUMBER_BLOCK_COMPRESSED);
uint64_t currentDecompressions =
options.statistics->getTickerCount(NUMBER_BLOCK_DECOMPRESSED);
// Check that compressions do not occur when turned off
for (int i = 0; i < kNumKeysWritten; ++i) {
// compressible string
ASSERT_OK(Put(Key(i), rnd.RandomString(128) + std::string(128, 'a')));
}
ASSERT_OK(Flush());
ASSERT_EQ(options.statistics->getTickerCount(NUMBER_BLOCK_COMPRESSED)
- currentCompressions, 0);
for (int i = 0; i < kNumKeysWritten; ++i) {
auto r = Get(Key(i));
}
ASSERT_EQ(options.statistics->getTickerCount(NUMBER_BLOCK_DECOMPRESSED)
- currentDecompressions, 0);
}
TEST_F(DBStatisticsTest, MutexWaitStatsDisabledByDefault) {
Options options = CurrentOptions();
options.create_if_missing = true;
options.statistics = ROCKSDB_NAMESPACE::CreateDBStatistics();
CreateAndReopenWithCF({"pikachu"}, options);
const uint64_t kMutexWaitDelay = 100;
ThreadStatusUtil::TEST_SetStateDelay(ThreadStatus::STATE_MUTEX_WAIT,
kMutexWaitDelay);
ASSERT_OK(Put("hello", "rocksdb"));
ASSERT_EQ(TestGetTickerCount(options, DB_MUTEX_WAIT_MICROS), 0);
ThreadStatusUtil::TEST_SetStateDelay(ThreadStatus::STATE_MUTEX_WAIT, 0);
}
TEST_F(DBStatisticsTest, MutexWaitStats) {
Options options = CurrentOptions();
options.create_if_missing = true;
options.statistics = ROCKSDB_NAMESPACE::CreateDBStatistics();
options.statistics->set_stats_level(StatsLevel::kAll);
CreateAndReopenWithCF({"pikachu"}, options);
const uint64_t kMutexWaitDelay = 100;
ThreadStatusUtil::TEST_SetStateDelay(ThreadStatus::STATE_MUTEX_WAIT,
kMutexWaitDelay);
ASSERT_OK(Put("hello", "rocksdb"));
ASSERT_GE(TestGetTickerCount(options, DB_MUTEX_WAIT_MICROS), kMutexWaitDelay);
ThreadStatusUtil::TEST_SetStateDelay(ThreadStatus::STATE_MUTEX_WAIT, 0);
}
TEST_F(DBStatisticsTest, ResetStats) {
Options options = CurrentOptions();
options.create_if_missing = true;
options.statistics = ROCKSDB_NAMESPACE::CreateDBStatistics();
DestroyAndReopen(options);
for (int i = 0; i < 2; ++i) {
// pick arbitrary ticker and histogram. On first iteration they're zero
// because db is unused. On second iteration they're zero due to Reset().
ASSERT_EQ(0, TestGetTickerCount(options, NUMBER_KEYS_WRITTEN));
HistogramData histogram_data;
options.statistics->histogramData(DB_WRITE, &histogram_data);
ASSERT_EQ(0.0, histogram_data.max);
if (i == 0) {
// The Put() makes some of the ticker/histogram stats nonzero until we
// Reset().
ASSERT_OK(Put("hello", "rocksdb"));
ASSERT_EQ(1, TestGetTickerCount(options, NUMBER_KEYS_WRITTEN));
options.statistics->histogramData(DB_WRITE, &histogram_data);
ASSERT_GT(histogram_data.max, 0.0);
options.statistics->Reset();
}
}
}
TEST_F(DBStatisticsTest, ExcludeTickers) {
Options options = CurrentOptions();
options.statistics = ROCKSDB_NAMESPACE::CreateDBStatistics();
DestroyAndReopen(options);
options.statistics->set_stats_level(StatsLevel::kExceptTickers);
ASSERT_OK(Put("foo", "value"));
ASSERT_EQ(0, options.statistics->getTickerCount(BYTES_WRITTEN));
options.statistics->set_stats_level(StatsLevel::kExceptHistogramOrTimers);
Reopen(options);
ASSERT_EQ("value", Get("foo"));
ASSERT_GT(options.statistics->getTickerCount(BYTES_READ), 0);
}
} // namespace ROCKSDB_NAMESPACE
int main(int argc, char** argv) {
ROCKSDB_NAMESPACE::port::InstallStackTraceHandler();
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}