Changyu Bi
2620c85638
Summary: add option MultiScanArgs::use_async_io option and implementation for using ReadAsync() for multiscan. Read requests are submitted during Prepare() and polled during actual scanning. Pull Request resolved: https://github.com/facebook/rocksdb/pull/13932 Test Plan: - updated existing unit test to use async_io. - crash test: `python3 -u ./tools/db_crashtest.py whitebox --iterpercent=60 --prefix_size=-1 --prefixpercent=0 --readpercent=0 --test_batches_snapshots=0 --use_multiscan=1 --read_fault_one_in=0 --kill_random_test=88888 --interval=60 --multiscan_use_async_io=1 --mmap_read=0` Benchmark: - Default multiscan benchmark: ``` Set up: /db_bench --benchmarks="fillseq,compact" --disable_wal=1 --threads=1 --num_levels=1 --compaction_style=2 --fifo_compaction_max_table_files_size_mb=1000 --write_buffer_size=268435456 Without async IO: ./db_bench --db="/tmp/rocksdbtest-543376/dbbench" --use_existing_db=1 --benchmarks=multiscan --disable_auto_compactions=1 --seek_nexts=100 --threads=32 --duration=10 --statistics=1 --use_direct_reads=1 --multiscan_use_async_io=0 multiscan : 415.569 micros/op 75805 ops/sec 10.355 seconds 784968 operations; (multscans:24999) rocksdb.read.async.micros COUNT : 0 With asycn IO: ./db_bench --db="/tmp/rocksdbtest-543376/dbbench" --use_existing_db=1 --benchmarks=multiscan --disable_auto_compactions=1 --seek_nexts=100 --threads=32 --duration=10 --statistics=1 --use_direct_reads=1 --multiscan_use_async_io=1 multiscan : 413.236 micros/op 76044 ops/sec 10.375 seconds 788968 operations; (multscans:24999) rocksdb.read.async.micros COUNT : 3916499 Similar performance. ``` - Larger scan, more scans per multiscan, do not coalesce IO so that async IO can progress while scanning, and use one thread: ``` multiscan_stride = 1000 multiscan_size = 100 seek_nexts = 1000 ./db_bench --db="/tmp/rocksdbtest-543376/dbbench" --use_existing_db=1 --benchmarks=multiscan --disable_auto_compactions=1 --threads=1 --duration=10 --statistics=0 --use_direct_reads=1 --cache_size=2097152 --multiscan_size=100 --multiscan_stride=1000 --seek_nexts=1000 --seed=1 --multiscan_coalesce_threshold=0 --multiscan_use_async_io=0 Without async IO: multiscan : 20495.205 micros/op 48 ops/sec 10.002 seconds 488 operations; (multscans:488) With async IO: multiscan : 18337.883 micros/op 54 ops/sec 10.013 seconds 546 operations; (multscans:546) ~10% improvement in throughput ``` Reviewed By: xingbowang Differential Revision: D82077818 Pulled By: cbi42 fbshipit-source-id: 66e32cf4039183c4841827409286dfbaa6dfbcd8
RocksDB: A Persistent Key-Value Store for Flash and RAM Storage
RocksDB is developed and maintained by Facebook Database Engineering Team. It is built on earlier work on LevelDB by Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com)
This code is a library that forms the core building block for a fast key-value server, especially suited for storing data on flash drives. It has a Log-Structured-Merge-Database (LSM) design with flexible tradeoffs between Write-Amplification-Factor (WAF), Read-Amplification-Factor (RAF) and Space-Amplification-Factor (SAF). It has multi-threaded compactions, making it especially suitable for storing multiple terabytes of data in a single database.
Start with example usage here: https://github.com/facebook/rocksdb/tree/main/examples
See the github wiki for more explanation.
The public interface is in include/. Callers should not include or
rely on the details of any other header files in this package. Those
internal APIs may be changed without warning.
Questions and discussions are welcome on the RocksDB Developers Public Facebook group and email list on Google Groups.
License
RocksDB is dual-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). You may select, at your option, one of the above-listed licenses.