Motivation:
DuplicatedByteBuf can be used for any ByteBuf implementations and so can not do any optimizations that could be done
when AbstractByteBuf is duplicated.
Modifications:
- Add DuplicatedAbstractByteBuf that can eliminate range and reference count checks for _get* and _set* methods.
Result:
Faster DuplicatedByteBuf implementations for AbstractByteBuf sub-classes.
Motivation:
Calling AbstractByteBuf.toString(..., Charset) is used quite frequently by users but produce a lot of GC.
Modification:
- Use a FastThreadLocal to store the CharBuffer that are needed for decoding.
- Use internalNioBuffer(...) when possible
Result:
Less object creation / Less GC
Motiviation:
Checking reference count on every access on a ByteBuf can have some big performance overhead depending on how the access pattern is. If the user is sure that there are no reference count errors on his side it should be possible to disable the check and so gain the max performance.
Modification:
- Add io.netty.buffer.bytebuf.checkAccessible system property which allows to disable the checks. Enabled by default.
- Add microbenchmark
Result:
Increased performance for operations on the ByteBuf.
Motivation:
We should minimize and optimize bound checks as much as possible to get the most out of performance.
Modifications:
- Use bitwise operations to remove branching
- Remove branches when possible
Result:
Better performance for various operations.
Motivation:
ByteBufUtil.writeUtf8(...) / writeUsAscii(...) can use a fast-path when writing into AbstractByteBuf. We should try to unwrap WrappedByteBuf implementations so
we are able to do the same on wrapped AbstractByteBuf instances.
Modifications:
- Try to unwrap WrappedByteBuf to use the fast-path
Result:
Faster writing of utf8 and usascii for WrappedByteBuf instances.
Motivation:
As toString() is often used while logging we need to ensure this produces no exception.
Modifications:
Ensure we never throw an IllegalReferenceCountException.
Result:
Be able to log without produce exceptions.
Motivation:
We need to ensure all markers are reset when doing an allocation via the PooledByteBufAllocator. This was not the always the case.
Modifications:
Move all logic that needs to get executed when reuse a PooledByteBuf into one place and call it.
Result:
Correct behavior
Motivation:
The configurable property value recently added was not logged like others properties.
Modifications:
Added debug log with effective value applied.
Result:
Consistent with other properties
Motivation:
Leak detector, when it detects a leak, will print the last 5 stack
traces that touched the ByteBuf. In some cases that might not be enough
to identify the root cause of the leak.
Also, sometimes users might not be interested in tracing all the
operations on the buffer, but just the ones that are affecting the
reference count.
Modifications:
Added command line properties to override default values:
* Allow to configure max number of stack traces to collect
* Allow to only record retain/release operation on buffers
Result:
Users can increase the number of stack traces to debug buffer leaks
with lot of retain/release operations.
Motivation:
Currently the "derived" buffer will only ever be recycled if the release call is made on the "derived" object, and the "wrapped" buffer ends up being "fully released" (aka refcount goes to 0). From my experience this is not the common use case and thus the "derived" buffers will not be recycled.
Modifications:
- revert https://github.com/netty/netty/pull/3788
Result:
Less complexity, and less code to create new objects in majority of cases.
Motivation:
Even though MemoryRegionCache$Entry instances are allocated through a recycler they are not properly recycled,
leaving a lot of instances to be GCed along with Recycler$DefaultHandle objects.
Fixes#4071
Modification:
Recycle Entry when done using it.
Result:
Less GCed objects.
Motivation:
As we modify the position of the passed in ByteBuffer's this methods are not thread-safe.
Modifications:
Duplicate the input ByteBuffers before copy the content to byte[].
Result:
Unpooled.copiedBuffer(ByteBuffer) and copiedBuffer(ByteBuffer...) is now thread-safe.
Motivation:
The javadoc of ByteBuf contained some out-dated code.
Modifications:
Update code example in javadoc to use netty 4+ API
Result:
Correct javadocs
Motivation:
FixedCompositeByteBuf does not properly implement a number of methods for
copying its content to direct buffers and output streams
Modifications:
Replace improper use of capacity() with readableBytes() when computing offesets during writes
Result:
Copying works correctly
This implementation does not produce as much GC pressure as CompositeByteBuf and so is prefered,
for writing an array of ByteBufs. Be aware that FixedCompositeByteBuf is readonly.
When using this in a project that make heavy use of CompositeByteBuf for writes we was able to cut
down allocation to a half.
Motivation:
At the moment we use 1 * cores as default mimimum for pool arenas. This can easily lead to conditions as we use 2 * cores as default for EventLoop's when using NIO or EPOLL. If we choose a smaller number we will run into hotspots as allocation and deallocation needs to be synchronized on the PoolArena.
Modifications:
Change the default number of arenas to 2 * cores.
Result:
Less conditions when using the default settings.
Motivation:
Dumping the content of a ByteBuf in a hex format is very useful.
Modifications:
Move code into ByteBufUtil so its easy to reuse.
Result:
Easy to reuse dumping code.
Motivation:
PoolThreadCache did only cache allocations if the allocation and deallocation Thread were the same. This is not optimal as often people write from differen thread then the actual EventLoop thread.
Modification:
- Add MpscArrayQueue which was forked from jctools and lightly modified.
- Use MpscArrayQueue for caches and always add buffer back to the cache that belongs to the allocation thread.
Result:
ThreadPoolCache is now also usable and so gives performance improvements when allocation and deallocation thread are different.
Performance when using same thread for allocation and deallocation is noticable worse then before.
Motivation:
Currently we hold a lock on the PoolArena when we allocate / free PoolSubpages, which is wasteful as this also affects "normal" allocations. The same is true vice-verse.
Modifications:
Ensure we synchronize on the head of the PoolSubPages pool. This is done per size and so it is possible to concurrently allocate / deallocate PoolSubPages with different sizes, and also normal allocations.
Result:
Less condition and so faster allocation/deallocation.
Before this commit:
xxx:~/wrk $ ./wrk -H 'Connection: keep-alive' -d 120 -c 256 -t 16 -s scripts/pipeline-many.lua http://xxx:8080/plaintext
Running 2m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 17.61ms 29.52ms 689.73ms 97.27%
Req/Sec 278.93k 41.97k 351.04k 84.83%
530527460 requests in 2.00m, 71.64GB read
Requests/sec: 4422226.13
Transfer/sec: 611.52MB
After this commit:
xxx:~/wrk $ ./wrk -H 'Connection: keep-alive' -d 120 -c 256 -t 16 -s scripts/pipeline-many.lua http://xxx:8080/plaintext
Running 2m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 15.85ms 24.50ms 681.61ms 97.42%
Req/Sec 287.14k 38.39k 360.33k 85.88%
547902773 requests in 2.00m, 73.99GB read
Requests/sec: 4567066.11
Transfer/sec: 631.55MB
This is reproducable every time.
Motiviation:
At the moment we sometimes hold the lock on the PoolArena during destroy a PoolChunk. This is not needed.
Modification:
- Ensure we not hold the lock during destroy a PoolChunk
- Move all synchronized usage in PoolArena
- Cleanup
Result:
Less condition.
Motivation:
The PooledByteBufAllocator is more or less a black-box atm. We need to expose some metrics to allow the user to get a better idea how to tune it.
Modifications:
- Expose different metrics via PooledByteBufAllocator
- Add *Metrics interfaces
Result:
It is now easy to gather metrics and detail about the PooledByteBufAllocator and so get a better understanding about resource-usage etc.
Motivation:
At the moment when calling slice(...) or duplicate(...) on a Pooled*ByteBuf a new SlicedByteBuf or DuplicatedByteBuf. This can create a lot of GC.
Modifications:
Add PooledSlicedByteBuf and PooledDuplicatedByteBuf which will be used when a PooledByteBuf is used.
Result:
Less GC.
Motivation:
From the javadocs of ByteBuf.duplicate() it is not clear if the reader and writer marks will be duplicated.
Modifications:
Add sentence to clarify that marks will not be duplicated.
Result:
Clear semantics.
Motivation:
When allocate a PooledByteBuf we need to ensure to also reset the markers for the readerIndex and writerIndex.
Modifications:
- Correct reset the markers
- Add test-case for it
Result:
Correctly reset markers.
Motiviation:
When tried to allocate tiny and small sized and failed to serve these out of the PoolSubPage we exit the synchronization
block just to enter it again when call allocateNormal(...).
Modification:
Not exit the synchronized block until allocateNormal(...) is done.
Result:
Better performance.
Motivation:
The way of firstIndexOf and lastIndexOf iterating the ByteBuf is similar to forEachByte and forEachByteDesc, but have many range checks.
Modifications:
Use forEachByte and a IndexOfProcessor to find occurrence.
Result:
eliminate range checks
Motivation:
CompositeByteBuf.iterator() currently creates a new ArrayList and fill it with the ByteBufs, which is more expensive then it needs to be.
Modifications:
- Use special Iterator implementation
Result:
Less overhead when calling iterator()
Motivation:
When create NormalMemoryRegionCache for PoolThreadCache, we overbooked
cache array size. This means unnecessary overhead for thread local cache
as we will create multi cache enties for each element in cache array.
Modifications:
change:
int arraySize = Math.max(1, max / area.pageSize);
to:
int arraySize = Math.max(1, log2(max / area.pageSize) + 1);
Result:
Now arraySize won't introduce unnecessary overhead.
Changes to be committed:
modified: buffer/src/main/java/io/netty/buffer/PoolThreadCache.java
Motivation:
CompositeByteBuf has an iterator() method but fails to implement Iterable
Modifications:
Let CompositeByteBuf implement Iterable<ByteBuf>
Result:
Easier usage
Motivation:
We missed to dereference the chunk and tmpNioBuf when calling deallocate(). This means the GC can not collect these as we still hold a reference while have the PooledByteBuf in the recycler stack.
Modifications:
Dereference chunk and tmpNioBuf.
Result:
GC can collect things.
Motiviation:
At the moment we use FIFO for the PoolThreadCache which is sub-optimal as this may reduce the changes to have the cached memory actual still in the cpu-cache.
Modification:
- Change to use LIFO as this increase the chance to be able to serve buffers from the cpu-cache
Results:
Faster allocation out of the ThreadLocal cache.
Before the commit:
[xxx wrk]$ ./wrk -H 'Connection: keep-alive' -d 120 -c 256 -t 16 -s scripts/pipeline-many.lua http://xxx:8080/plaintext
Running 2m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 14.69ms 10.06ms 131.43ms 80.10%
Req/Sec 283.89k 40.37k 433.69k 66.81%
533859742 requests in 2.00m, 72.09GB read
Requests/sec: 4449510.51
Transfer/sec: 615.29MB
After the commit:
[xxx wrk]$ ./wrk -H 'Connection: keep-alive' -d 120 -c 256 -t 16 -s scripts/pipeline-many.lua http://xxx:8080/plaintext
Running 2m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 16.38ms 26.32ms 734.06ms 97.38%
Req/Sec 283.86k 39.31k 361.69k 83.38%
540836511 requests in 2.00m, 73.04GB read
Requests/sec: 4508150.18
Transfer/sec: 623.40MB
Motivation:
`Unpooled` javadoc's mentioned the generation of hex dump and swapping an integer's byte order,
which are actually provided by `ByteBufUtil`.
Modifications:
Sentence moved to `ByteBufUtil` javadoc.
Result:
`Unpooled` javadoc is correct.
