Motivation:
We rely on this functionality in PoolChunk, and a bug was caught by a non-deterministic test failure
Modification:
Went back to the Algorithms book, and reimplemented remove() the way it was meant to.
Result:
No test failures after 200.000 runs, so we have some confidence the code is correct now.
Motivation:
The uncached access to PoolChunk can be made faster, and avoid allocating boxed Longs, if we have a primitive hash map and priority queue implementation for it.
Modification:
Add bespoke primitive implementations of a hash map and a priority queue for PoolChunk.
Remove all the long-boxing caused by the previous implementation.
The hashmap is a linear probing map with a fairly short probe that keeps the search within a couple of cache lines.
The priority queue is the same binary heap algorithm that's described in Algorithms by Sedgewick and Wayne.
The implementation avoids the Long boxing by relying on a long[] array.
This makes the internal-remove method faster, which is an important operation in PoolChunk.
Result:
Roughly 13% performance uplift in buffer allocations that miss cache.
Motivation:
https://github.com/netty/netty/pull/10267 introduced a change that reduced the fragmentation. Unfortunally it also introduced a regression when it comes to caching of normal allocations. This can have a negative performance impact depending on the allocation sizes.
Modifications:
- Fix algorithm to calculate the array size for normal allocation caches
- Correctly calculate indeox for normal caches
- Add unit test
Result:
Fixes https://github.com/netty/netty/issues/10805
Motivation:
Passing a null value of byte[] to the `Unsafe.copyMemory(xxx)` would cause the JVM crash
Modification:
Add null checking before calling `PlatformDependent.copyMemory(src, xxx)`
Result:
Fixes#10791 .
Motivation:
https in xmlns URIs does not work and will let the maven release plugin fail:
```
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.779 s
[INFO] Finished at: 2020-11-10T07:45:21Z
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-release-plugin:2.5.3:prepare (default-cli) on project netty-parent: Execution default-cli of goal org.apache.maven.plugins:maven-release-plugin:2.5.3:prepare failed: The namespace xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" could not be added as a namespace to "project": The namespace prefix "xsi" collides with an additional namespace declared by the element -> [Help 1]
[ERROR]
```
See also https://issues.apache.org/jira/browse/HBASE-24014.
Modifications:
Use http for xmlns
Result:
Be able to use maven release plugin
Motivation:
PoolChunk maintains multiple PriorityQueue<Long> collections. The usage
of PoolChunk#removeAvailRun unboxes the Long values to long, and then
this method uses queue.remove(..) which will auto box the value back to
Long. This creates unnecessary allocations via Long.valueOf(long).
Modifications:
- Adjust method signature and usage of PoolChunk#removeAvailRun to avoid
boxing
Result:
Less allocations as a result of PoolChunk#removeAvailRun.
Motivation:
Some buffers implement ByteBuf#order(order) by wrapping themselves in a SwappedByteBuf.
The SwappedByteBuf is then responsible for swapping the byte order on accesses.
The explicitly little-endian accessor methods, however, should not be swapped to big-endian, but instead remain explicitly little-endian.
Modification:
The SwappedByteBuf was passing through calls to e.g. writeIntLE, to the big-endian equivalent, e.g. writeInt.
This has been changed so that these calls delegate to their explicitly little-endian counterpart.
Result:
This makes all buffers that make use of SwappedByteBuf for their endian-ness configuration, consistent with all the buffers that use other implementation strategies.
In the end, all buffers now behave exactly the same, when using their explicitly little-endian accessor methods.
Motivation:
HTTP is a plaintext protocol which means that someone may be able
to eavesdrop the data. To prevent this, HTTPS should be used whenever
possible. However, maintaining using https:// in all URLs may be
difficult. The nohttp tool can help here. The tool scans all the files
in a repository and reports where http:// is used.
Modifications:
- Added nohttp (via checkstyle) into the build process.
- Suppressed findings for the websites
that don't support HTTPS or that are not reachable
Result:
- Prevent using HTTP in the future.
- Encourage users to use HTTPS when they follow the links they found in
the code.
Motivation:
junit deprecated Assert.assertThat(...)
Modifications:
Use MatcherAssert.assertThat(...) as replacement for deprecated method
Result:
Less deprecation warnings
Motivation:
LGTM reports multiple issues. They need to be triaged,
and real ones should be fixed.
Modifications:
- Fixed multiple issues reported by LGTM, such as redundant conditions,
resource leaks, typos, possible integer overflows.
- Suppressed false-positives.
- Added a few testcases.
Result:
Fixed several possible issues, get rid of false alarms in the LGTM report.
Motivation:
As the PooledByteBufAllocator is a critical part of netty we should ensure it works as expected.
Modifications:
- Add a few more asserts to ensure we not see any corrupted state
- Null out slot in the subpage array once the subpage was freed and removed from the pool
- Merge methods into constructor as it was only called from the constructor anyway.
Result:
Code cleanup
Motivation:
- To make ensureWritable throw IOOBE when maxCapacity is exceeded, even if
the requested new capacity would overflow Integer.MAX_VALUE
Modification:
- AbstractByteBuf.ensureWritable0 is modified to detect when
targetCapacity has wrapped around
- Test added for correct behaviour in AbstractByteBufTest
Result:
- Calls to ensureWritable will always throw IOOBE when maxCapacity is
exceeded (and bounds checking is enabled)
Motivation:
writeUtf8 can suffer from inlining issues and/or megamorphic call-sites on the hot path due to ByteBuf hierarchy
Modifications:
Duplicate and specialize the code paths to reduce the need of polymorphic calls
Result:
Performance are more stable in user code
Motivation:
If ByteBufUtil.getBytes() is called with copy=false, it does not
correctly check that the underlying array can be shared in some cases.
In particular:
* It does not check that the arrayOffset() is zero. This causes it to
incorrectly return the underlying array if the other conditions are
met. The returned array will be longer than requested, with additional
unwanted bytes at its start.
* It assumes that the capacity() of the ByteBuf is equal to the backing
array length. This is not true for some types of ByteBuf, such as
PooledHeapByteBuf. This causes it to incorrectly return the underlying
array if the other conditions are met. The returned array will be
longer than requested, with additional unwanted bytes at its end.
Modifications:
This commit fixes the two bugs by:
* Checking that the arrayOffset() is zero before returning the
underlying array.
* Comparing the requested length to the underlying array's length,
rather than the ByteBuf's capacity, before returning the underlying
array.
This commit also adds a series of test cases for ByteBufUtil.getBytes().
Result:
ByteBufUtil.getBytes() now correctly checks whether the underlying array
can be shared or not.
The test cases will ensure the bug is not reintroduced in the future.
Motivation
This is used solely for the DataOutput#writeUTF8() method, which may
often not be used.
Modifications
Lazily construct the contained DataOutputStream in ByteBufOutputStream.
Result
Saves an allocation in some common cases
Motivation
ByteBuf has an isAccessible method which was introduced as part of ref
counting optimizations but there are some places still doing
accessibility checks by accessing the volatile refCnt() directly.
Modifications
- Have PooledNonRetained(Duplicate|Sliced)ByteBuf#isAccessible() use
their refcount delegate's isAccessible() method
- Add static isAccessible(buf) and ensureAccessible(buf) methods to
ByteBufUtil
(since ByteBuf#isAccessible() is package-private)
- Adjust DefaultByteBufHolder and similar classes to use these methods
rather than access refCnt() directly
Result
- More efficient accessibility checks in more places
Motivation:
We shouldn't call incSmallAllocation() in a synchronized block as its backed by a concurrent datastructure
Modifications:
Move call of incSmallAllocation() out of synchronized block
Result:
Minimize scope of synchronized block
Motivation:
For size from 512 bytes to chunkSize, we use a buddy algorithm. The
drawback is that it has a large internal fragmentation.
Modifications:
1. add SizeClassesMetric and SizeClasses
2. remove tiny size, now we have small, normal and huge size
3. rewrite the structure of PoolChunk
4. rewrite pooled allocate algorithm in PoolChunk
5. when allocate subpage, using lowest common multiple of pageSize and
elemSize instead of pageSize.
6. add more tests in PooledByteBufAllocatorTest and PoolArenaTest
Result:
Reduce internal fragmentation and closes#3910
Motivation:
We should include as much details as possible when throwing an IllegalArgumentException because of overflow in CompositeByteBuf
Modifications:
Add more details and factor out check into a static method to share code
Result:
Make it more clear why an operations failed
Motivation
An NPE was reported in #10245, caused by a regression introduced in
#8939. This in particular affects ByteToMessageDecoders that use the
COMPOSITE_CUMULATOR.
Modification
- Unwrap WrappedCompositeByteBufs passed to
CompositeByteBuf#addFlattenedComponents(...) method before accessing
internal components field
- Extend unit test to cover this case and ensure more of the
CompositeByteBuf tests are also run on the wrapped variant
Results
Fixes#10245
Motivation:
We can make use of our optimized implementations for UTF-8 and US-ASCII if the user request a copy of a sequence for these charsets
Modifications:
- Add fastpath implementation
- Add unit tests
Result:
Fixes https://github.com/netty/netty/issues/10205
Motivation:
We need to ensure we not overflow when adding buffers to a CompositeByteBuf
Modifications:
- Correctly validate overflow before adding to the internal storage
- Add testcase
Result:
Fixes https://github.com/netty/netty/issues/10194
Motivation:
We have found out that ByteBufUtil.indexOf can be inefficient for substring search on
ByteBuf, both in terms of algorithm complexity (worst case O(needle.readableBytes *
haystack.readableBytes)), and in constant factor (esp. on Composite buffers).
With implementation of more performant search algorithms we have seen improvements on
the order of magnitude.
Modifications:
This change introduces three search algorithms:
1. Knuth Morris Pratt - classical textbook algorithm, a good default choice.
2. Bit mask based algorithm - stable performance on any input, but limited to maximum
search substring (the needle) length of 64 bytes.
3. Aho–Corasick - worse performance and higher memory consumption than [1] and [2], but
it supports multiple substring (the needles) search simultaneously, by inspecting every
byte of the haystack only once.
Each algorithm processes every byte of underlying buffer only once, they are implemented
as ByteProcessor.
Result:
Efficient search algorithms with linear time complexity available in Netty (I will share
benchmark results in a comment on a PR).
Motivation:
PoolChunk requires a link to a PoolThreadCache to init ByteBuf. Currently the link is retrieved from a thread local: arena.parent.threadCache().
It has some performance cost. At the beginning of the allocation call the PoolThreadCache is already retrieved from the thread local. The reference can be propagated through the calls and used.
Modifications:
Replace second lookup of PoolThreadCache during ByteBuf init by propagation of a reference to PoolThreadCache down in the allocation stack explicitly
Result:
Improve performance of ByteBuf allocation
--Before--
Benchmark (size) (tokens) (useThreadCache) Mode Cnt Score Error Units
SimpleByteBufPooledAllocatorBenchmark.getAndRelease 123 0 true avgt 20 57.112 ± 1.004 ns/op
SimpleByteBufPooledAllocatorBenchmark.getAndRelease 123 100 true avgt 20 222.827 ± 1.307 ns/op
--After--
Benchmark (size) (tokens) (useThreadCache) Mode Cnt Score Error Units
SimpleByteBufPooledAllocatorBenchmark.getAndRelease 123 0 true avgt 20 50.732 ± 1.321 ns/op
SimpleByteBufPooledAllocatorBenchmark.getAndRelease 123 100 true avgt 20 216.892 ± 3.806 ns/op
Motivation:
PoolChunk.usage() method has non-trivial computations. It is used currently in hot path methods invoked when an allocation and de-allocation are happened.
The idea is to replace usage() output comparison against percent thresholds by Chunk.freeBytes plain comparison against absolute thresholds. In such way the majority of computations from the threshold conditions are moved to init logic.
Modifications:
Replace PoolChunk.usage() conditions in PoolChunkList with equivalent conditions for PoolChunk.freeBytes()
Result:
Improve performance of allocation and de-allocation of ByteBuf from normal size cache pool
Motivation:
The current implementation of log2 in PoolThreadCache uses a loop and less efficient than an version based on Integer.numberOfLeadingZeros (intrinsic).
Modifications:
Replace the current log2 implementation in PoolThreadCache with a version based on Integer.numberOfLeadingZeros
Result:
It can improve performance slightly during allocation and de-allocation of ByteBuf using pooled allocator.
