Fix log_write_bench -bytes_per_sync option. (#1375)
Hello and thanks for RocksDB,
When log_write_bench is run with the -bytes_per_sync option, the option does not influence any *sync* behaviour.
> strace -e trace=write,sync_file_range ./log_write_bench -record_interval 0 -record_size 1048576 -num_records 11 -bytes_per_sync 2097152 2>&1 | egrep '^(sync|write.*XXXX)'
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
I suspect that this is because the bytes_per_sync option now needs to be using a `WritableFileWriter` and not a `WritableFile`.
With the diff below applied, it changes to:
> strace -e trace=write,sync_file_range ./log_write_bench -record_interval 0 -record_size 1048576 -num_records 11 -bytes_per_sync 2097152 2>&1 | egrep '^(sync|write.*XXXX)'
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
sync_file_range(0x3, 0, 0x200000, 0x2) = 0
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
sync_file_range(0x3, 0x200000, 0x200000, 0x2) = 0
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
sync_file_range(0x3, 0x400000, 0x200000, 0x2) = 0
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
sync_file_range(0x3, 0x600000, 0x200000, 0x2) = 0
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
write(3, "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"..., 1048576) = 1048576
sync_file_range(0x3, 0x800000, 0x200000, 0x2) = 0
( Note that the first 1MB is not synced as mentioned in util/file_reader_writer.cc::WritableFileWriter::Flush() )
This diff also includes the fix from https://github.com/facebook/rocksdb/pull/1373
> diff -du util/log_write_bench.cc.orig util/log_write_bench.cc
--- util/log_write_bench.cc.orig 2016-10-04 12:06:29.115122580 -0400
+++ util/log_write_bench.cc 2016-10-05 07:24:09.677037576 -0400
@@ -14,6 +14,7 @@
#include <gflags/gflags.h>
#include "rocksdb/env.h"
+#include "util/file_reader_writer.h"
#include "util/histogram.h"
#include "util/testharness.h"
#include "util/testutil.h"
@@ -38,19 +39,21 @@
env_options.bytes_per_sync = FLAGS_bytes_per_sync;
unique_ptr<WritableFile> file;
env->NewWritableFile(file_name, &file, env_options);
+ unique_ptr<WritableFileWriter> writer;
+ writer.reset(new WritableFileWriter(std::move(file), env_options));
std::string record;
- record.assign('X', FLAGS_record_size);
+ record.assign(FLAGS_record_size, 'X');
HistogramImpl hist;
uint64_t start_time = env->NowMicros();
for (int i = 0; i < FLAGS_num_records; i++) {
uint64_t start_nanos = env->NowNanos();
- file->Append(record);
- file->Flush();
+ writer->Append(record);
+ writer->Flush();
if (FLAGS_enable_sync) {
- file->Sync();
+ writer->Sync(false);
}
hist.Add(env->NowNanos() - start_nanos);
Peter (Stig) Edwards