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
Summary:
if read_options.snapshot is not set, ::Get will take the last sequence number after taking a super-version and uses that as the sequence number. Theoretically max_eviceted_seq_ could advance this sequence number. This could lead ::IsInSnapshot that will be invoked by the ReadCallback to notice the absence of the snapshot. In this case, the ReadCallback should have passed a non-value to snap_released so that it could be set by the ::IsInSnapshot. The patch does that, and adds a unit test to verify it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5664
Differential Revision: D16614033
Pulled By: maysamyabandeh
fbshipit-source-id: 06fb3fd4aacd75806ed1a1acec7961f5d02486f2
Summary:
The first key is used to defer reading the data block until this file gets to the top of merging iterator's heap. For short range scans, most files never make it to the top of the heap, so this change can reduce read amplification by a lot sometimes.
Consider the following workload. There are a few data streams (we'll be calling them "logs"), each stream consisting of a sequence of blobs (we'll be calling them "records"). Each record is identified by log ID and a sequence number within the log. RocksDB key is concatenation of log ID and sequence number (big endian). Reads are mostly relatively short range scans, each within a single log. Writes are mostly sequential for each log, but writes to different logs are randomly interleaved. Compactions are disabled; instead, when we accumulate a few tens of sst files, we create a new column family and start writing to it.
So, a typical sst file consists of a few ranges of blocks, each range corresponding to one log ID (we use FlushBlockPolicy to cut blocks at log boundaries). A typical read would go like this. First, iterator Seek() reads one block from each sst file. Then a series of Next()s move through one sst file (since writes to each log are mostly sequential) until the subiterator reaches the end of this log in this sst file; then Next() switches to the next sst file and reads sequentially from that, and so on. Often a range scan will only return records from a small number of blocks in small number of sst files; in this case, the cost of initial Seek() reading one block from each file may be bigger than the cost of reading the actually useful blocks.
Neither iterate_upper_bound nor bloom filters can prevent reading one block from each file in Seek(). But this PR can: if the index contains first key from each block, we don't have to read the block until this block actually makes it to the top of merging iterator's heap, so for short range scans we won't read any blocks from most of the sst files.
This PR does the deferred block loading inside value() call. This is not ideal: there's no good way to report an IO error from inside value(). As discussed with siying offline, it would probably be better to change InternalIterator's interface to explicitly fetch deferred value and get status. I'll do it in a separate PR.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5289
Differential Revision: D15256423
Pulled By: al13n321
fbshipit-source-id: 750e4c39ce88e8d41662f701cf6275d9388ba46a
Summary:
Depending on the config, manual compaction (leveled compaction style) does following compactions:
L0->L1
L1->L2
...
Ln-1 -> Ln
Ln -> Ln
The final Ln -> Ln compaction is partly unnecessary as it recompacts all the files that were just generated by the Ln-1 -> Ln. We should avoid recompacting such files. This rule should be applied to Lmax only.
Resolves issue https://github.com/facebook/rocksdb/issues/4995
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5138
Differential Revision: D14940106
Pulled By: miasantreble
fbshipit-source-id: 8d3cf5507a17e76f3333cfd4bac5256d005636e5
Summary:
This is my latest round of changes to add missing items to RocksJava. More to come in future PRs.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4833
Differential Revision: D14152266
Pulled By: sagar0
fbshipit-source-id: d6cff67e26da06c131491b5cf6911a8cd0db0775
Summary:
This PR adds public `GetStatsHistory` API to retrieve stats history in the form of an std map. The key of the map is the timestamp in microseconds when the stats snapshot is taken, the value is another std map from stats name to stats value (stored in std string). Two DBOptions are introduced: `stats_persist_period_sec` (default 10 minutes) controls the intervals between two snapshots are taken; `max_stats_history_count` (default 10) controls the max number of history snapshots to keep in memory. RocksDB will stop collecting stats snapshots if `stats_persist_period_sec` is set to 0.
(This PR is the in-memory part of https://github.com/facebook/rocksdb/pull/4535)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4748
Differential Revision: D13961471
Pulled By: miasantreble
fbshipit-source-id: ac836d401ecb84ea92216bf9966f969dedf4ad04
Summary:
Expose common stats min,max,count,sum via statistics JNI. These stats are not fully exposed on the Java side as is, but are available on the native side.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4742
Differential Revision: D13403766
Pulled By: ajkr
fbshipit-source-id: 5b70f7bd3fb7490aab73dcbd09f13490fce5c773
Summary:
Updating the `HistogramType.java` and `TickerType.java` to expose and correct metrics for statistics callbacks.
Moved `NO_ITERATOR_CREATED` to the proper stat name and deprecated `NO_ITERATORS`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4733
Differential Revision: D13466936
Pulled By: sagar0
fbshipit-source-id: a58d1edcc07c7b68c3525b1aa05828212c89c6c7
Summary:
Added back `NO_ITERATORS` and moved `NO_ITERATOR_CREATED` to the end of `toCppTickers`.
This is a leftover fix which is needed in addition to a138e351bc to correctly convert java tickers to c++ tickers. a138e351bc only updated `toJavaTickerType` but both `toJavaTickerType` and `toCppTickers` need to be changed.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4719
Differential Revision: D13208847
Pulled By: sagar0
fbshipit-source-id: 53a42f3d6ffe04034acfde972d73040b92b4c1af
Summary:
- Added back the `NO_ITERATORS` that was removed in 5945e16dfc.
- Marked it as deprecated since it is no longer populated, but kept for API compatibility.
- Made sure the new tickers, `NO_ITERATOR_CREATED` and `NO_ITERATOR_DELETED`, are appended at the end of the enum, in case people are relying on the int values.
The change where `NO_ITERATOR_CREATED` and `NO_ITERATOR_DELETED` were introduced is unreleased so I believe it is ok to change their ordering.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4701
Differential Revision: D13142887
Pulled By: ajkr
fbshipit-source-id: 29a336ce5b46632ce50ad42ccc4a29013f71d6d6
Summary:
Currently, `Statistics` can record tick by `recordTick()` whose second parameter is an `uint64_t`.
That means tick can only increase.
If we want to reduce tick, we have to work around like `RecordTick(statistics_, NO_ITERATORS, uint64_t(-1));`.
That's kind of a hack.
So, this PR divide `NO_ITERATORS` into two counters `NO_ITERATOR_CREATED` and `NO_ITERATOR_DELETE`, making the counters increase only.
Fixes#3013 .
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4498
Differential Revision: D10395010
Pulled By: sagar0
fbshipit-source-id: cfb523b22a37411c794b4e9da090f1ae30293db2
Summary:
Closes https://github.com/facebook/rocksdb/issues/4195
CompactRangeOptions are available the CPP API, but not in the Java API. This PR adds CompactRangeOptions to the Java API and adds an overloaded compactRange() method. See https://github.com/facebook/rocksdb/issues/4195 for the original discussion.
This change supports all fields of CompactRangeOptions, including the required enum converters in the JNI portal.
Significant changes:
- Make CompactRangeOptions available in the compactRange() for Java.
- Deprecate other compactRange() methods that have individual option params, like in the CPP code.
- Migrate rocksdb_compactrange_helper() to CompactRangeOptions.
- Add Java unit tests for CompactRangeOptions.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4220
Differential Revision: D9380007
Pulled By: sagar0
fbshipit-source-id: 6af6c334f221427f1997b33fb24c3986b092fed6
Summary:
Fixes#3391.
This change adds a `DeleteRange` method to `SstFileWriter` and adds
support for ingesting SSTs with range deletion tombstones. This is
important for applications that need to atomically ingest SSTs while
clearing out any existing keys in a given key range.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/3778
Differential Revision: D8821836
Pulled By: anand1976
fbshipit-source-id: ca7786c1947ff129afa703dab011d524c7883844
Summary:
Exposes BackupEngine::CreateNewBackupWithMetadata and BackupInfo metadata to the Java API.
Full disclaimer, I'm not familiar with JNI stuff, so I might have forgotten something (hopefully no memory leaks!). I also tried to find contributing guidelines but didn't see any, but I hope the PR style is consistent with the rest of the code base.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4111
Differential Revision: D8811180
Pulled By: ajkr
fbshipit-source-id: e38b3e396c7574328c2a1a0e55acc8d092b6a569
Summary:
1. Add a new ticker stat rocksdb.number.multiget.keys.found to track the
number of keys successfully read
2. Update rocksdb.memtable.hit/miss in DBImpl::MultiGet(). It was being done in
DBImpl::GetImpl(), but not MultiGet
Closes https://github.com/facebook/rocksdb/pull/3730
Differential Revision: D7677364
Pulled By: anand1976
fbshipit-source-id: af22bd0ef8ddc5cf2b4244b0a024e539fe48bca5
Summary:
This PR comments out the rest of the unused arguments which allow us to turn on the -Wunused-parameter flag. This is the second part of a codemod relating to https://github.com/facebook/rocksdb/pull/3557.
Closes https://github.com/facebook/rocksdb/pull/3662
Differential Revision: D7426121
Pulled By: Dayvedde
fbshipit-source-id: 223994923b42bd4953eb016a0129e47560f7e352
Summary:
Add a new histogram stat called rocksdb.db.flush.micros for memtable
flush
Closes https://github.com/facebook/rocksdb/pull/3269
Differential Revision: D6559496
Pulled By: anand1976
fbshipit-source-id: f5c771ba2568630458751795e8c37a493ff9b14d
Summary:
This diff adds a new ticker stat, NUMBER_ITER_SKIP, to count the
number of internal keys skipped during iteration. Keys can be skipped
due to deletes, or lower sequence number, or higher sequence number
than the one requested.
Also, fix the issue when StatisticsData is naturally aligned on cacheline boundary,
padding becomes a zero size array, which the Windows compiler doesn't
like. So add a cacheline worth of padding in that case to keep it happy.
We cannot conditionally add padding as gcc doesn't allow using sizeof
in preprocessor directives.
Closes https://github.com/facebook/rocksdb/pull/3177
Differential Revision: D6353897
Pulled By: anand1976
fbshipit-source-id: 441d5a09af9c4e22e7355242dfc0c7b27aa0a6c2
Summary:
Java's `Status.SubCode` was out of sync with `include/rocksdb/status.h:SubCode`.
When running out of disc space this led to an `IllegalArgumentException` because of an invalid status code, rather than just returning the corresponding status code without an exception.
I added the missing status codes.
By this, we keep the behaviour of throwing an `IllegalArgumentException` in case of newly added status codes that are defined in C but not in Java.
We could think of an alternative strategy: add in Java another code "UnknownCode" which acts as a catch-all for all those status codes that are not yet mirrored from C to Java. This approach would never throw an exception but simply return a non-OK status-code.
I think the current approach of throwing an Exception in case of a C/Java inconsistency is fine, but if you have some opinion on the alternative strategy, then feel free to comment here.
Closes https://github.com/facebook/rocksdb/pull/3050
Differential Revision: D6129682
Pulled By: sagar0
fbshipit-source-id: f2bf44caad650837cffdcb1f93eb793b43580c66
Summary:
This PR also includes some cleanup, bugfixes and refactoring of the Java API. However these are really pre-cursors on the road to CompactionFilterFactory support.
Closes https://github.com/facebook/rocksdb/pull/1241
Differential Revision: D6012778
Pulled By: sagar0
fbshipit-source-id: 0774465940ee99001a78906e4fed4ef57068ad5c
Summary:
This adds almost all missing options to RocksJava
Closes https://github.com/facebook/rocksdb/pull/2039
Differential Revision: D4779991
Pulled By: siying
fbshipit-source-id: 4a1bf28
Summary:
I have manually audited the entire RocksJava code base.
Sorry for the large pull-request, I have broken it down into many small atomic commits though.
My initial intention was to fix the warnings that appear when running RocksJava on Java 8 with `-Xcheck:jni`, for example when running `make jtest` you would see many errors similar to:
```
WARNING in native method: JNI call made without checking exceptions when required to from CallObjectMethod
WARNING in native method: JNI call made without checking exceptions when required to from CallVoidMethod
WARNING in native method: JNI call made without checking exceptions when required to from CallStaticVoidMethod
...
```
A few of those warnings still remain, however they seem to come directly from the JVM and are not directly related to RocksJava; I am in contact with the OpenJDK hostpot-dev mailing list about these - http://mail.openjdk.java.net/pipermail/hotspot-dev/2017-February/025981.html.
As a result of fixing these, I realised we were not r
Closes https://github.com/facebook/rocksdb/pull/1890
Differential Revision: D4591758
Pulled By: siying
fbshipit-source-id: 7f7fdf4
Summary:
Fixes compile error:
In file included from ./util/statistics.h:17:0,
from ./util/stop_watch.h:8,
from ./util/perf_step_timer.h:9,
from ./util/iostats_context_imp.h:8,
from ./util/posix_logger.h:27,
from ./port/util_logger.h:18,
from ./db/auto_roll_logger.h:15,
from db/auto_roll_logger.cc:6:
./util/thread_local.h:65:16: error: 'function' in namespace 'std' does not name a template type
typedef std::function<void(void*, void*)> FoldFunc;
Closes https://github.com/facebook/rocksdb/pull/1656
Differential Revision: D4318702
Pulled By: yiwu-arbug
fbshipit-source-id: 8c5d17a
Summary:
Needed for working with `get` after `merge` on a WBWI.
Closes https://github.com/facebook/rocksdb/pull/1093
Differential Revision: D4137978
Pulled By: yhchiang
fbshipit-source-id: e18d50d
Summary:
Merge pull request #665 by adamretter
Exposes BackupEngine from C++ to the Java API. Previously only BackupableDB was available
Test Plan: BackupEngineTest.java
Reviewers: fyrz, igor, ankgup87, yhchiang
Reviewed By: yhchiang
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D42873
Summary:
RocksDB offers the possibility to set different compression types
on a per level basis. This shall be also available using RocksJava.
Test Plan:
make rocksdbjava
make jtest
Reviewers: adamretter, yhchiang, ankgup87
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D35577
Summary:
Before this change overflowing size_t values led to a checked Exception.
After that change:
size_t overflows on 32-Bit architecture throw now an IllegalArgumentException,
which removes the necessity for a developer to catch these Exceptions explicitly.
This is especially an advantage for developers targeting 64-Bit systems because
it is not necessary anymore to catch exceptions which are never thrown on a 64-Bit
system.
Test Plan:
make clean jclean rocksdbjava jtest
mvn -f rocksjni.pom package
Reviewers: adamretter, yhchiang, ankgup87
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D34923
