rocksdb

Commit Graph

Author	SHA1	Message	Date
Adam Retter	7242dae7fe	Improve RocksJava Comparator (#6252 An error occurred ) Summary: This is a redesign of the API for RocksJava comparators with the aim of improving performance. It also simplifies the class hierarchy. NOTE: This breaks backwards compatibility for existing 3rd party Comparators implemented in Java... so we need to consider carefully which release branches this goes into. Previously when implementing a comparator in Java the developer had a choice of subclassing either `DirectComparator` or `Comparator` which would use direct and non-direct byte-buffers resepectively (via `DirectSlice` and `Slice`). In this redesign there we have eliminated the overhead of using the Java Slice classes, and just use `ByteBuffer`s. The `ComparatorOptions` supplied when constructing a Comparator allow you to choose between direct and non-direct byte buffers by setting `useDirect`. In addition, the `ComparatorOptions` now allow you to choose whether a ByteBuffer is reused over multiple comparator calls, by setting `maxReusedBufferSize > 0`. When buffers are reused, ComparatorOptions provides a choice of mutex type by setting `useAdaptiveMutex`. --- [JMH benchmarks previously indicated](https://github.com/facebook/rocksdb/pull/6241#issue-356398306) that the difference between C++ and Java for implementing a comparator was ~7x slowdown in Java. With these changes, when reusing buffers and guarding access to them via mutexes the slowdown is approximately the same. However, these changes offer a new facility to not reuse mutextes, which reduces the slowdown to ~5.5x in Java. We also offer a `thread_local` mechanism for reusing buffers, which reduces slowdown to ~5.2x in Java (closes https://github.com/facebook/rocksdb/pull/4425). These changes also form a good base for further optimisation work such as further JNI lookup caching, and JNI critical. --- These numbers were captured without jemalloc. With jemalloc, the performance improves for all tests, and the Java slowdown reduces to between 4.8x and 5.x. ``` ComparatorBenchmarks.put native_bytewise thrpt 25 124483.795 ± 2032.443 ops/s ComparatorBenchmarks.put native_reverse_bytewise thrpt 25 114414.536 ± 3486.156 ops/s ComparatorBenchmarks.put java_bytewise_non-direct_reused-64_adaptive-mutex thrpt 25 17228.250 ± 1288.546 ops/s ComparatorBenchmarks.put java_bytewise_non-direct_reused-64_non-adaptive-mutex thrpt 25 16035.865 ± 1248.099 ops/s ComparatorBenchmarks.put java_bytewise_non-direct_reused-64_thread-local thrpt 25 21571.500 ± 871.521 ops/s ComparatorBenchmarks.put java_bytewise_direct_reused-64_adaptive-mutex thrpt 25 23613.773 ± 8465.660 ops/s ComparatorBenchmarks.put java_bytewise_direct_reused-64_non-adaptive-mutex thrpt 25 16768.172 ± 5618.489 ops/s ComparatorBenchmarks.put java_bytewise_direct_reused-64_thread-local thrpt 25 23921.164 ± 8734.742 ops/s ComparatorBenchmarks.put java_bytewise_non-direct_no-reuse thrpt 25 17899.684 ± 839.679 ops/s ComparatorBenchmarks.put java_bytewise_direct_no-reuse thrpt 25 22148.316 ± 1215.527 ops/s ComparatorBenchmarks.put java_reverse_bytewise_non-direct_reused-64_adaptive-mutex thrpt 25 11311.126 ± 820.602 ops/s ComparatorBenchmarks.put java_reverse_bytewise_non-direct_reused-64_non-adaptive-mutex thrpt 25 11421.311 ± 807.210 ops/s ComparatorBenchmarks.put java_reverse_bytewise_non-direct_reused-64_thread-local thrpt 25 11554.005 ± 960.556 ops/s ComparatorBenchmarks.put java_reverse_bytewise_direct_reused-64_adaptive-mutex thrpt 25 22960.523 ± 1673.421 ops/s ComparatorBenchmarks.put java_reverse_bytewise_direct_reused-64_non-adaptive-mutex thrpt 25 18293.317 ± 1434.601 ops/s ComparatorBenchmarks.put java_reverse_bytewise_direct_reused-64_thread-local thrpt 25 24479.361 ± 2157.306 ops/s ComparatorBenchmarks.put java_reverse_bytewise_non-direct_no-reuse thrpt 25 7942.286 ± 626.170 ops/s ComparatorBenchmarks.put java_reverse_bytewise_direct_no-reuse thrpt 25 11781.955 ± 1019.843 ops/s ``` Pull Request resolved: https://github.com/facebook/rocksdb/pull/6252 Differential Revision: D19331064 Pulled By: pdillinger fbshipit-source-id: 1f3b794e6a14162b2c3ffb943e8c0e64a0c03738	5 years ago
Adam Retter	6477075f2c	JMH microbenchmarks for RocksJava (#6241 An error occurred ) Summary: This is the start of some JMH microbenchmarks for RocksJava. Such benchmarks can help us decide on performance improvements of the Java API. At the moment, I have only added benchmarks for various Comparator options, as that is one of the first areas where I want to improve performance. I plan to expand this to many more tests. Details of how to compile and run the benchmarks are in the `README.md`. A run of these on a XEON 3.5 GHz 4vCPU (QEMU Virtual CPU version 2.5+) / 8GB RAM KVM with Ubuntu 18.04, OpenJDK 1.8.0_232, and gcc 8.3.0 produced the following: ``` # Run complete. Total time: 01:43:17 REMEMBER: The numbers below are just data. To gain reusable insights, you need to follow up on why the numbers are the way they are. Use profilers (see -prof, -lprof), design factorial experiments, perform baseline and negative tests that provide experimental control, make sure the benchmarking environment is safe on JVM/OS/HW level, ask for reviews from the domain experts. Do not assume the numbers tell you what you want them to tell. Benchmark (comparatorName) Mode Cnt Score Error Units ComparatorBenchmarks.put native_bytewise thrpt 25 122373.920 ± 2200.538 ops/s ComparatorBenchmarks.put java_bytewise_adaptive_mutex thrpt 25 17388.201 ± 1444.006 ops/s ComparatorBenchmarks.put java_bytewise_non-adaptive_mutex thrpt 25 16887.150 ± 1632.204 ops/s ComparatorBenchmarks.put java_direct_bytewise_adaptive_mutex thrpt 25 15644.572 ± 1791.189 ops/s ComparatorBenchmarks.put java_direct_bytewise_non-adaptive_mutex thrpt 25 14869.601 ± 2252.135 ops/s ComparatorBenchmarks.put native_reverse_bytewise thrpt 25 116528.735 ± 4168.797 ops/s ComparatorBenchmarks.put java_reverse_bytewise_adaptive_mutex thrpt 25 10651.975 ± 545.998 ops/s ComparatorBenchmarks.put java_reverse_bytewise_non-adaptive_mutex thrpt 25 10514.224 ± 930.069 ops/s ``` Indicating a ~7x difference between comparators implemented natively (C++) and those implemented in Java. Let's see if we can't improve on that in the near future... Pull Request resolved: https://github.com/facebook/rocksdb/pull/6241 Differential Revision: D19290410 Pulled By: pdillinger fbshipit-source-id: 25d44bf3a31de265502ed0c5d8a28cf4c7cb9c0b	5 years ago

Author

SHA1

Message

Date

Adam Retter

7242dae7fe

Improve RocksJava Comparator (#6252)

Summary:
This is a redesign of the API for RocksJava comparators with the aim of improving performance. It also simplifies the class hierarchy.

**NOTE**: This breaks backwards compatibility for existing 3rd party Comparators implemented in Java... so we need to consider carefully which release branches this goes into.

Previously when implementing a comparator in Java the developer had a choice of subclassing either `DirectComparator` or `Comparator` which would use direct and non-direct byte-buffers resepectively (via `DirectSlice` and `Slice`).

In this redesign there we have eliminated the overhead of using the Java Slice classes, and just use `ByteBuffer`s. The `ComparatorOptions` supplied when constructing a Comparator allow you to choose between direct and non-direct byte buffers by setting `useDirect`.

In addition, the `ComparatorOptions` now allow you to choose whether a ByteBuffer is reused over multiple comparator calls, by setting `maxReusedBufferSize > 0`. When buffers are reused, ComparatorOptions provides a choice of mutex type by setting `useAdaptiveMutex`.

 ---
[JMH benchmarks previously indicated](https://github.com/facebook/rocksdb/pull/6241#issue-356398306) that the difference between C++ and Java for implementing a comparator was ~7x slowdown in Java.

With these changes, when reusing buffers and guarding access to them via mutexes the slowdown is approximately the same. However, these changes offer a new facility to not reuse mutextes, which reduces the slowdown to ~5.5x in Java. We also offer a `thread_local` mechanism for reusing buffers, which reduces slowdown to ~5.2x in Java (closes https://github.com/facebook/rocksdb/pull/4425).

These changes also form a good base for further optimisation work such as further JNI lookup caching, and JNI critical.

 ---
These numbers were captured without jemalloc. With jemalloc, the performance improves for all tests, and the Java slowdown reduces to between 4.8x and 5.x.

```
ComparatorBenchmarks.put                                                native_bytewise  thrpt   25  124483.795 ± 2032.443  ops/s
ComparatorBenchmarks.put                                        native_reverse_bytewise  thrpt   25  114414.536 ± 3486.156  ops/s
ComparatorBenchmarks.put              java_bytewise_non-direct_reused-64_adaptive-mutex  thrpt   25   17228.250 ± 1288.546  ops/s
ComparatorBenchmarks.put          java_bytewise_non-direct_reused-64_non-adaptive-mutex  thrpt   25   16035.865 ± 1248.099  ops/s
ComparatorBenchmarks.put                java_bytewise_non-direct_reused-64_thread-local  thrpt   25   21571.500 ±  871.521  ops/s
ComparatorBenchmarks.put                  java_bytewise_direct_reused-64_adaptive-mutex  thrpt   25   23613.773 ± 8465.660  ops/s
ComparatorBenchmarks.put              java_bytewise_direct_reused-64_non-adaptive-mutex  thrpt   25   16768.172 ± 5618.489  ops/s
ComparatorBenchmarks.put                    java_bytewise_direct_reused-64_thread-local  thrpt   25   23921.164 ± 8734.742  ops/s
ComparatorBenchmarks.put                              java_bytewise_non-direct_no-reuse  thrpt   25   17899.684 ±  839.679  ops/s
ComparatorBenchmarks.put                                  java_bytewise_direct_no-reuse  thrpt   25   22148.316 ± 1215.527  ops/s
ComparatorBenchmarks.put      java_reverse_bytewise_non-direct_reused-64_adaptive-mutex  thrpt   25   11311.126 ±  820.602  ops/s
ComparatorBenchmarks.put  java_reverse_bytewise_non-direct_reused-64_non-adaptive-mutex  thrpt   25   11421.311 ±  807.210  ops/s
ComparatorBenchmarks.put        java_reverse_bytewise_non-direct_reused-64_thread-local  thrpt   25   11554.005 ±  960.556  ops/s
ComparatorBenchmarks.put          java_reverse_bytewise_direct_reused-64_adaptive-mutex  thrpt   25   22960.523 ± 1673.421  ops/s
ComparatorBenchmarks.put      java_reverse_bytewise_direct_reused-64_non-adaptive-mutex  thrpt   25   18293.317 ± 1434.601  ops/s
ComparatorBenchmarks.put            java_reverse_bytewise_direct_reused-64_thread-local  thrpt   25   24479.361 ± 2157.306  ops/s
ComparatorBenchmarks.put                      java_reverse_bytewise_non-direct_no-reuse  thrpt   25    7942.286 ±  626.170  ops/s
ComparatorBenchmarks.put                          java_reverse_bytewise_direct_no-reuse  thrpt   25   11781.955 ± 1019.843  ops/s
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6252

Differential Revision: D19331064

Pulled By: pdillinger

fbshipit-source-id: 1f3b794e6a14162b2c3ffb943e8c0e64a0c03738

Adam Retter

6477075f2c

JMH microbenchmarks for RocksJava (#6241)

Summary:
This is the start of some JMH microbenchmarks for RocksJava.

Such benchmarks can help us decide on performance improvements of the Java API.

At the moment, I have only added benchmarks for various Comparator options, as that is one of the first areas where I want to improve performance. I plan to expand this to many more tests.

Details of how to compile and run the benchmarks are in the `README.md`.

A run of these on a XEON 3.5 GHz 4vCPU (QEMU Virtual CPU version 2.5+) / 8GB RAM KVM with Ubuntu 18.04, OpenJDK 1.8.0_232, and gcc 8.3.0 produced the following:

```
# Run complete. Total time: 01:43:17

REMEMBER: The numbers below are just data. To gain reusable insights, you need to follow up on
why the numbers are the way they are. Use profilers (see -prof, -lprof), design factorial
experiments, perform baseline and negative tests that provide experimental control, make sure
the benchmarking environment is safe on JVM/OS/HW level, ask for reviews from the domain experts.
Do not assume the numbers tell you what you want them to tell.

Benchmark                                         (comparatorName)   Mode  Cnt       Score       Error  Units
ComparatorBenchmarks.put                           native_bytewise thrpt   25   122373.920 ±  2200.538  ops/s
ComparatorBenchmarks.put              java_bytewise_adaptive_mutex thrpt   25    17388.201 ±  1444.006  ops/s
ComparatorBenchmarks.put          java_bytewise_non-adaptive_mutex thrpt   25    16887.150 ±  1632.204  ops/s
ComparatorBenchmarks.put       java_direct_bytewise_adaptive_mutex thrpt   25    15644.572 ±  1791.189  ops/s
ComparatorBenchmarks.put   java_direct_bytewise_non-adaptive_mutex thrpt   25    14869.601 ±  2252.135  ops/s
ComparatorBenchmarks.put                   native_reverse_bytewise thrpt   25   116528.735 ±  4168.797  ops/s
ComparatorBenchmarks.put      java_reverse_bytewise_adaptive_mutex thrpt   25    10651.975 ±   545.998  ops/s
ComparatorBenchmarks.put  java_reverse_bytewise_non-adaptive_mutex thrpt   25    10514.224 ±   930.069  ops/s
```

Indicating a ~7x difference between comparators implemented natively (C++) and those implemented in Java. Let's see if we can't improve on that in the near future...
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6241

Differential Revision: D19290410

Pulled By: pdillinger

fbshipit-source-id: 25d44bf3a31de265502ed0c5d8a28cf4c7cb9c0b

2 Commits (f9ffeaed3fe76252a6f6baa7a968ea807cfa02d3)