Revision 7103559f49b46b3287973045f741c0679e3e9e44 authored by Sagar Vemuri on 21 June 2018, 18:02:49 UTC, committed by Facebook Github Bot on 21 June 2018, 18:13:08 UTC
Summary: This PR extends the improvements in #3282 to also work when using Direct IO. We see **4.5X performance improvement** in seekrandom benchmark doing long range scans, when using direct reads, on flash. **Description:** This change improves the performance of iterators doing long range scans (e.g. big/full index or table scans in MyRocks) by using readahead and prefetching additional data on each disk IO, and storing in a local buffer. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan. **Implementation Details:** - Used `FilePrefetchBuffer` as the underlying buffer to store the readahead data. `FilePrefetchBuffer` can now take file_reader, readahead_size and max_readahead_size as input to the constructor, and automatically do readahead. - `FilePrefetchBuffer::TryReadFromCache` can now call `FilePrefetchBuffer::Prefetch` if readahead is enabled. - `AlignedBuffer` (which is the underlying store for `FilePrefetchBuffer`) now takes a few additional args in `AlignedBuffer::AllocateNewBuffer` to allow copying data from the old buffer. - Made sure not to re-read partial chunks of data that were already available in the buffer, from device again. - Fixed a couple of cases where `AlignedBuffer::cursize_` was not being properly kept up-to-date. **Constraints:** - Similar to #3282, this gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value). - Since the prefetched data is stored in a temporary buffer allocated on heap, this could increase the memory usage if you have many iterators doing long range scans simultaneously. - Enabled only for user reads, and disabled for compactions. Compaction reads are controlled by the options `use_direct_io_for_flush_and_compaction` and `compaction_readahead_size`, and the current feature takes precautions not to mess with them. **Benchmarks:** I used the same benchmark as used in #3282. Data fill: ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes ``` Do a long range scan: Seekrandom with large number of nexts ``` TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -use_direct_reads -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram ``` ``` Before: seekrandom : 37939.906 micros/op 26 ops/sec; 29.2 MB/s (1636 of 1999 found) With this change: seekrandom : 8527.720 micros/op 117 ops/sec; 129.7 MB/s (6530 of 7999 found) ``` ~4.5X perf improvement. Taken on an average of 3 runs. Closes https://github.com/facebook/rocksdb/pull/3884 Differential Revision: D8082143 Pulled By: sagar0 fbshipit-source-id: 4d7a8561cbac03478663713df4d31ad2620253bb
1 parent 524c6e6
error_filter.py
# 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).
'''Filter for error messages in test output:
- Receives merged stdout/stderr from test on stdin
- Finds patterns of known error messages for test name (first argument)
- Prints those error messages to stdout
'''
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
import re
import sys
class ErrorParserBase(object):
def parse_error(self, line):
'''Parses a line of test output. If it contains an error, returns a
formatted message describing the error; otherwise, returns None.
Subclasses must override this method.
'''
raise NotImplementedError
class GTestErrorParser(ErrorParserBase):
'''A parser that remembers the last test that began running so it can print
that test's name upon detecting failure.
'''
_GTEST_NAME_PATTERN = re.compile(r'\[ RUN \] (\S+)$')
# format: '<filename or "unknown file">:<line #>: Failure'
_GTEST_FAIL_PATTERN = re.compile(r'(unknown file|\S+:\d+): Failure$')
def __init__(self):
self._last_gtest_name = 'Unknown test'
def parse_error(self, line):
gtest_name_match = self._GTEST_NAME_PATTERN.match(line)
if gtest_name_match:
self._last_gtest_name = gtest_name_match.group(1)
return None
gtest_fail_match = self._GTEST_FAIL_PATTERN.match(line)
if gtest_fail_match:
return '%s failed: %s' % (
self._last_gtest_name, gtest_fail_match.group(1))
return None
class MatchErrorParser(ErrorParserBase):
'''A simple parser that returns the whole line if it matches the pattern.
'''
def __init__(self, pattern):
self._pattern = re.compile(pattern)
def parse_error(self, line):
if self._pattern.match(line):
return line
return None
class CompilerErrorParser(MatchErrorParser):
def __init__(self):
# format: '<filename>:<line #>:<column #>: error: <error msg>'
super(CompilerErrorParser, self).__init__(r'\S+:\d+:\d+: error:')
class ScanBuildErrorParser(MatchErrorParser):
def __init__(self):
super(ScanBuildErrorParser, self).__init__(
r'scan-build: \d+ bugs found.$')
class DbCrashErrorParser(MatchErrorParser):
def __init__(self):
super(DbCrashErrorParser, self).__init__(r'\*\*\*.*\^$|TEST FAILED.')
class WriteStressErrorParser(MatchErrorParser):
def __init__(self):
super(WriteStressErrorParser, self).__init__(
r'ERROR: write_stress died with exitcode=\d+')
class AsanErrorParser(MatchErrorParser):
def __init__(self):
super(AsanErrorParser, self).__init__(
r'==\d+==ERROR: AddressSanitizer:')
class UbsanErrorParser(MatchErrorParser):
def __init__(self):
# format: '<filename>:<line #>:<column #>: runtime error: <error msg>'
super(UbsanErrorParser, self).__init__(r'\S+:\d+:\d+: runtime error:')
class ValgrindErrorParser(MatchErrorParser):
def __init__(self):
# just grab the summary, valgrind doesn't clearly distinguish errors
# from other log messages.
super(ValgrindErrorParser, self).__init__(r'==\d+== ERROR SUMMARY:')
class CompatErrorParser(MatchErrorParser):
def __init__(self):
super(CompatErrorParser, self).__init__(r'==== .*[Ee]rror.* ====$')
class TsanErrorParser(MatchErrorParser):
def __init__(self):
super(TsanErrorParser, self).__init__(r'WARNING: ThreadSanitizer:')
_TEST_NAME_TO_PARSERS = {
'punit': [CompilerErrorParser, GTestErrorParser],
'unit': [CompilerErrorParser, GTestErrorParser],
'release': [CompilerErrorParser, GTestErrorParser],
'unit_481': [CompilerErrorParser, GTestErrorParser],
'release_481': [CompilerErrorParser, GTestErrorParser],
'clang_unit': [CompilerErrorParser, GTestErrorParser],
'clang_release': [CompilerErrorParser, GTestErrorParser],
'clang_analyze': [CompilerErrorParser, ScanBuildErrorParser],
'code_cov': [CompilerErrorParser, GTestErrorParser],
'unity': [CompilerErrorParser, GTestErrorParser],
'lite': [CompilerErrorParser],
'lite_test': [CompilerErrorParser, GTestErrorParser],
'stress_crash': [CompilerErrorParser, DbCrashErrorParser],
'write_stress': [CompilerErrorParser, WriteStressErrorParser],
'asan': [CompilerErrorParser, GTestErrorParser, AsanErrorParser],
'asan_crash': [CompilerErrorParser, AsanErrorParser, DbCrashErrorParser],
'ubsan': [CompilerErrorParser, GTestErrorParser, UbsanErrorParser],
'ubsan_crash': [CompilerErrorParser, UbsanErrorParser, DbCrashErrorParser],
'valgrind': [CompilerErrorParser, GTestErrorParser, ValgrindErrorParser],
'tsan': [CompilerErrorParser, GTestErrorParser, TsanErrorParser],
'format_compatible': [CompilerErrorParser, CompatErrorParser],
'run_format_compatible': [CompilerErrorParser, CompatErrorParser],
'no_compression': [CompilerErrorParser, GTestErrorParser],
'run_no_compression': [CompilerErrorParser, GTestErrorParser],
'regression': [CompilerErrorParser],
'run_regression': [CompilerErrorParser],
}
def main():
if len(sys.argv) != 2:
return 'Usage: %s <test name>' % sys.argv[0]
test_name = sys.argv[1]
if test_name not in _TEST_NAME_TO_PARSERS:
return 'Unknown test name: %s' % test_name
error_parsers = []
for parser_cls in _TEST_NAME_TO_PARSERS[test_name]:
error_parsers.append(parser_cls())
for line in sys.stdin:
line = line.strip()
for error_parser in error_parsers:
error_msg = error_parser.parse_error(line)
if error_msg is not None:
print(error_msg)
if __name__ == '__main__':
sys.exit(main())
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