Motivation:
Found performance issues via FindBugs and PMD.
Modifications:
- Removed unnecessary boxing/unboxing operations in DefaultTextHeaders.convertToInt(CharSequence) and DefaultTextHeaders.convertToLong(CharSequence). A boxed primitive is created from a string, just to extract the unboxed primitive value.
- Added a static modifier for DefaultHttp2Connection.ParentChangedEvent class. This class is an inner class, but does not use its embedded reference to the object which created it. This reference makes the instances of the class larger, and may keep the reference to the creator object alive longer than necessary.
- Added a static compiled Pattern to avoid compile it each time it is used when we need to replace some part of authority.
- Improved using of StringBuilders.
Result:
Performance improvements.
Motivation:
ChannelPromiseAggregator and ChannelPromiseNotifiers only allow
consumers to work with Channels as the result type. Generic versions
of these classes allow consumers to aggregate or broadcast the results
of an asynchronous execution with other result types.
Modifications:
Add PromiseAggregator and PromiseNotifier. Add unit tests for both.
Remove code in ChannelPromiseAggregator and ChannelPromiseNotifier and
modify them to extend the new base classes.
Result:
Consumers can now aggregate or broadcast the results of an asynchronous
execution with results types other than Channel.
Related: #2945
Motivation:
Some special handlers such as TrafficShapingHandler need to override the
writability of a Channel to throttle the outbound traffic.
Modifications:
Add a new indexed property called 'user-defined writability flag' to
ChannelOutboundBuffer so that a handler can override the writability of
a Channel easily.
Result:
A handler can override the writability of a Channel using an unsafe API.
For example:
Channel ch = ...;
ch.unsafe().outboundBuffer().setUserDefinedWritability(1, false);
Related: #2034
Motivation:
Some users want to mock Bootstrap (or ServerBootstrap), and thus they
should not be final but be fully overridable and extensible.
Modifications:
Remove finals wherever possible
Result:
@daschl is happy.
Related: #2964
Motivation:
Writing a zero-length FileRegion to an NIO channel will lead to an
infinite loop.
Modification:
- Do not write a zero-length FileRegion by protecting with proper 'if'.
- Update the testsuite
Result:
Another bug fixed
Motivation:
When a datagram packet is sent to a destination where nobody actually listens to,
the server O/S will respond with an ICMP Port Unreachable packet.
The ICMP Port Unreachable packet is translated into PortUnreachableException by JDK.
PortUnreachableException is not a harmful exception that prevents a user from sending a datagram.
Therefore, we should not close a datagram channel when PortUnreachableException is caught.
Modifications:
- Do not close a channel when the caught exception is PortUnreachableException.
Result:
A datagram channel is not closed unexpectedly anymore.
Motivation:
JDK's exception messages triggered by a connection attempt failure do
not contain the related remote address in its message. We currently
append the remote address to ConnectException's message, but I found
that we need to cover more exception types such as SocketException.
Modifications:
- Add AbstractUnsafe.annotateConnectException() to de-duplicate the
code that appends the remote address
Result:
- Less duplication
- A transport implementor can annotate connection attempt failure
message more easily
Motiviation:
Before this change, autoRead was a volatile boolean accessed directly. Any thread that invoked the DefaultChannelConfig#setAutoRead(boolean) method would read the current value of autoRead, and then set a new value. If the old value did not match the new value, some action would be immediately taken as part of the same method call.
As volatile only provides happens-before consistency, there was no guarantee that the calling thread was actually the thread mutating the state of the autoRead variable (such that it should be the one to invoke the follow-up actions). For example, with 3 threads:
* Thread 1: get = false
* Thread 1: set = true
* Thread 1: invokes read()
* Thread 2: get = true
* Thread 3: get = true
* Thread 2: set = false
* Thread 2: invokes autoReadCleared()
* Event Loop receives notification from the Selector that data is available, but as autoRead has been cleared, cancels the operation and removes read interest
* Thread 3: set = true
This results in a livelock - autoRead is set true, but no reads will happen even if data is available (as readyOps). The only way around this livelock currently is to set autoRead to false, and then back to true.
Modifications:
Write access to the autoRead variable is now made using the getAndSet() method of an AtomicIntegerFieldUpdater, AUTOREAD_UPDATER. This also changed the type of the underlying autoRead variable to be an integer, as no AtomicBooleanFieldUpdater class exists. Boolean logic is retained by assuming that 1 is true and 0 is false.
Result:
There is no longer a race condition between retrieving the old value of the autoRead variable and setting a new value.
Motivation:
We used the wrong EventExecutor to notify for bind failures if a late registration was done.
Modifications:
Use the correct EventExecutor to notify and only use the GlobelEventExecutor if the registration fails itself.
Result:
The correct Thread will do the notification.
When a ChannelOutboundBuffer contains ByteBufs followed by a FileRegion,
removeBytes() will fail with a ClassCastException. It should break the
loop instead.
f31c630c8c was causing
SocketGatheringWriteTest to fail because it does not take the case where
an empty buffer exists in a gathering write.
When there is an empty buffer in a gathering write, the number of
buffers returned by ChannelOutboundBuffer.nioBuffer() and the actual
number of write attemps can differ.
To remove the write requests correctly, a byte transport must use
ChannelOutboundBuffer.removeBytes()
Motivation:
Because of an incorrect logic in teh EmbeddedChannel constructor it is not possible to use EmbeddedChannel with a ChannelInitializer as constructor argument. This is because it adds the internal LastInboundHandler to its ChannelPipeline before it register itself to the EventLoop.
Modifications:
First register self to EventLoop before add LastInboundHandler to the ChannelPipeline.
Result:
It's now possible to use EmbeddedChannel with ChannelInitializer.
Motivation:
Due a regression NioSocketChannel.doWrite(...) will throw a ClassCastException if you do something like:
channel.write(bytebuf);
channel.write(fileregion);
channel.flush();
Modifications:
Correctly handle writing of different message types by using the correct message count while loop over them.
Result:
No more ClassCastException
Motivation:
The previous fix did disable the caching of ByteBuffers completely which can cause performance regressions. This fix makes sure we use nioBuffers() for all writes in NioSocketChannel and so prevent data-corruptions. This is still kind of a workaround which will be replaced by a more fundamental fix later.
Modifications:
- Revert 4059c9f354
- Use nioBuffers() for all writes to prevent data-corruption
Result:
No more data-corruption but still retain the original speed.
Motivation:
At the moment we expand the ByteBuffer[] when we have more then 1024 ByteBuffer to write and replace the stored instance in its FastThreadLocal. This is not needed and may even harm performance on linux as IOV_MAX is 1024 and so this may cause the JVM to do an array copy.
Modifications:
Just exit the nioBuffers() method if we can not fit more ByteBuffer in the array. This way we will pick them up on the next call.
Result:
Remove uncessary array copy and simplify the code.
Motivation:
We cache the ByteBuffers in ChannelOutboundBuffer.nioBuffers() for the Entries in the ChannelOutboundBuffer to reduce some overhead. The problem is this can lead to data-corruption if an incomplete write happens and next time we try to do a non-gathering write.
To fix this we should remove the caching which does not help a lot anyway and just make the code buggy.
Modifications:
Remove the caching of ByteBuffers.
Result:
No more data-corruption.
Motivation:
Sometimes ChannelHandler need to queue writes to some point and then process these. We currently have no datastructure for this so the user will use an Queue or something like this. The problem is with this Channel.isWritable() will not work as expected and so the user risk to write to fast. That's exactly what happened in our SslHandler. For this purpose we need to add a special datastructure which will also take care of update the Channel and so be sure that Channel.isWritable() works as expected.
Modifications:
- Add PendingWriteQueue which can be used for this purpose
- Make use of PendingWriteQueue in SslHandler
Result:
It is now possible to queue writes in a ChannelHandler and still have Channel.isWritable() working as expected. This also fixes#2752.
Motivation:
While trying to merge our ChannelOutboundBuffer changes we've made last
week, I realized that we have quite a bit of conflicting changes at 4.1
and master. It was primarily because we added
ChannelOutboundBuffer.beforeAdd() and moved some logic there, such as
direct buffer conversion.
However, this is not possible with the changes we've made for 4.0. We
made ChannelOutboundBuffer final for example.
Maintaining multiple branch is already getting painful and having
different core will make it even worse, so I think we should keep the
differences between 4.0 and other branches minimal.
Modifications:
- Move ChannelOutboundBuffer.safeRelease() to ReferenceCountUtil
- Add ByteBufUtil.threadLocalBuffer()
- Backported from ThreadLocalPooledDirectByteBuf
- Make most methods in AbstractUnsafe final
- Add AbstractChannel.filterOutboundMessage() so that a transport can
convert a message to another (e.g. heap -> off-heap), and also
reject unsupported messages
- Move all direct buffer conversions to filterOutboundMessage()
- Move all type checks to filterOutboundMessage()
- Move AbstractChannel.checkEOF() to OioByteStreamChannel, because it's
the only place it is used at all
- Remove ChannelOutboundBuffer.current(Object), because it's not used
anymore
- Add protected direct buffer conversion methods to AbstractNioChannel
and AbstractEpollChannel so that they can be used by their subtypes
- Update all transport implementations according to the changes above
Result:
- The missing extension point in 4.0 has been added.
- AbstractChannel.filterOutboundMessage()
- Thanks to the new extension point, we moved all transport-specific
logic from ChannelOutboundBuffer to each transport implementation
- We can copy most of the transport implementations in 4.0 to 4.1 and
master now, so that we have much less merge conflict when we modify
the core.
Motivation:
We expose ChannelOutboundBuffer in Channel.Unsafe but it is not possible
to create a new ChannelOutboundBuffer without an AbstractChannel. This
makes it impossible to write a Channel implementation that does not
extend AbstractChannel.
Modifications:
- Change ChannelOutboundBuffer to take a Channel as constructor argument.
- Add javadocs
Result:
ChannelOutboundBuffer can be used with a Channel implemention that does
not extend AbstractChannel.
Motivation:
Our ChannelOutboundBuffer implementation is not based on ArrayDeque anymore so we can remove the license notice for it.
Modifications:
Remove license of deque and entry in NOTICE.
Result:
Cleaned up licenses
Motivation:
When a ChannelOutboundBuffer contains a series of entries whose messages
are all empty buffers, EpollSocketChannel sometimes fails to remove
them. As a result, the result of the write(EmptyByteBuf) is never
notified, making the user application hang.
Modifications:
- Add ChannelOutboundBuffer.removeBytes(long) method that updates the
progress of the entries and removes them as much as the specified
number of written bytes. It also updates the reader index of
partially flushed buffer.
- Make both NioSocketChannel and EpollSocketChannel use it to reduce
code duplication
- Replace EpollSocketChannel.updateOutboundBuffer()
- Refactor EpollSocketChannel.doWrite() for simplicity
- Split doWrite() into doWriteSingle() and doWriteMultiple()
- Do not add a zero-length buffer to IovArray
- Do not perform any real I/O when the size of IovArray is 0
Result:
Another regression is gone.
Related issue: #2717, #2710, #2704, #2693
Motivation:
When ChannelOutboundBuffer.nioBuffers() iterates over the linked list of
entries, it is not supposed to visit unflushed entries, but it does.
Modifications:
- Make sure ChannelOutboundBuffer.nioBuffers() stops the iteration before
it visits an unflushed entry
- Add isFlushedEntry() to reduce the chance of the similar mistakes
Result:
Another regression is gone.
Motivation:
ChannelOutboundBuffer.forEachFlushedMessage() visits even an unflushed
messages.
Modifications:
Stop the loop if the currently visiting entry is unflushedEntry.
Result:
forEachFlushedMessage() behaves correctly.
- ChannelOutboundBuffer.Entry.buffers -> bufs for consistency
- Make Native.IOV_MAX final because it's a constant
- Naming changes
- FlushedMessageProcessor -> MessageProcessor just in case we can
reuse it for unflushed messages in the future
- Add ChannelOutboundBuffer.Entry.recycle() that does not return the
next entry, and use it wherever possible
- Javadoc clean-up
Motivation:
While benchmarking the native transport, I noticed that gathering write
is not as fast as expected. It was due to the fact that we have to do a
lot of array copies to put the buffer addresses into the iovec struct
array.
Modifications:
Introduce a new class called IovArray, which allows to fill buffers
directly into an off-heap array of iovec structs, so that it can be
passed over to JNI without any extra array copies.
Result:
Big performance improvement when doing gathering writes:
Before:
[nmaurer@xxx]~% wrk/wrk -H 'Host: localhost' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8' -H 'Connection: keep-alive' -d 120 -c 256 -t 16 --pipeline 256 http://xxx:8080/plaintext
Running 2m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 23.44ms 16.37ms 259.57ms 91.77%
Req/Sec 181.99k 31.69k 304.60k 78.12%
346544071 requests in 2.00m, 46.48GB read
Requests/sec: 2887885.09
Transfer/sec: 396.59MB
After:
[nmaurer@xxx]~% wrk/wrk -H 'Host: localhost' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8' -H 'Connection: keep-alive' -d 120 -c 256 -t 16 --pipeline 256 http://xxx:8080/plaintext
Running 2m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 21.93ms 16.33ms 305.73ms 92.34%
Req/Sec 194.56k 33.75k 309.33k 77.04%
369617503 requests in 2.00m, 49.57GB read
Requests/sec: 3080169.65
Transfer/sec: 423.00MB
Motivation:
73dfd7c01b introduced various test
failures because:
- EpollSocketChannel.doWrite() raised a NullPointerException when
notifying the write progress.
- ChannelOutboundBuffer.nioBuffers() did not expand the internal array
when the pending entries contained more than 1024 buffers, dropping
the remainder.
Modifications:
- Fix the NPE in EpollSocketChannel by removing an unnecessary progress
update
- Expand the thread-local buffer array if there is not enough room,
which was the original behavior dropped by the offending commit
Result:
Regression is gone.
Motiviation:
ChannelOuboundBuffer uses often too much memory. This is especially a problem if you want to serve a lot of connections. This is due the fact that it uses 2 arrays internally. One if used as a circular buffer and store the Entries that are never released (ChannelOutboundBuffer is pooled) and one is used to hold the ByteBuffers that are used for gathering writes.
Modifications:
Rewrite ChannelOutboundBuffer to remove these two arrays by:
- Make Entry recyclable and use it as linked Node
- Remove the circular buffer which was used for the Entries as we use a Linked-List like structure now
- Remove the array that did hold the ByteBuffers and replace it by an ByteBuffer array that is hold by a FastThreadLocal. We use a fixed capacity of 1024 here which is fine as we share these anyway.
- ChannelOuboundBuffer is not recyclable anymore as it is now a "light-weight" object. We recycle the internally used Entries instead.
Result:
Less memory footprint and resource usage. Performance seems to be a bit better but most likely as we not need to expand any arrays anymore.
Benchmark before change:
[nmaurer@xxx]~% wrk/wrk -H 'Host: localhost' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8' -H 'Connection: keep-alive' -d 120 -c 256 -t 16 --pipeline 256 http://xxx:8080/plaintext
Running 2m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 26.88ms 67.47ms 1.26s 97.97%
Req/Sec 191.81k 28.22k 255.63k 83.86%
364806639 requests in 2.00m, 48.92GB read
Requests/sec: 3040101.23
Transfer/sec: 417.49MB
Benchmark after change:
[nmaurer@xxx]~% wrk/wrk -H 'Host: localhost' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8' -H 'Connection: keep-alive' -d 120 -c 256 -t 16 --pipeline 256 http://xxx:8080/plaintext
Running 2m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 22.22ms 17.22ms 301.77ms 90.13%
Req/Sec 194.98k 41.98k 328.38k 70.50%
371816023 requests in 2.00m, 49.86GB read
Requests/sec: 3098461.44
Transfer/sec: 425.51MB
Motivation:
We have some inconsistency when handling writes. Sometimes we call ChannelOutboundBuffer.progress(...) also for complete writes and sometimes not. We should call it always.
Modifications:
Correctly call ChannelOuboundBuffer.progress(...) for complete and incomplete writes.
Result:
Consistent behavior
Motivation:
ChannelOutboundBuffer is basically a circular array queue of its entry
objects. Once an entry is created in the array, it is never nulled out
to reduce the allocation cost.
However, because it is a circular queue, the array almost always ends up
with as many entry instances as the size of the array, regardless of the
number of pending writes.
At worst case, a channel might have only 1 pending writes at maximum
while creating 32 entry objects, where 32 is the initial capacity of the
array.
Modifications:
- Reduce the initial capacity of the circular array queue to 4.
- Make the initial capacity of the circular array queue configurable
Result:
We spend 4 times less memory for entry objects under certain
circumstances.
Motivation:
At the moment ChannelOutboundBuffer.nioBuffers() returns null if something is contained in the ChannelOutboundBuffer which is not a ByteBuf. This is a problem for two reasons:
1 - In the javadocs we state that it will never return null
2 - We may do a not optimal write as there may be things that could be written via gathering writes
Modifications:
Change ChannelOutboundBuffer.nioBuffers() to never return null but have it contain all ByteBuffer that were found before the non ByteBuf. This way we can do a gathering write and also conform to the javadocs.
Result:
Better speed and also correct implementation in terms of the api.
Motivation:
Now Netty has a few problems with null values.
Modifications:
- Check File in DiskFileUpload.toString().
If File is null we will get NPE when calling toString() method.
- Check Result<String> in MqttDecoder.decodeConnectionPayload(...).
- Check Unsafe before calling unsafe.getClass() in PlatformDependent0 static block.
- Removed unnecessary null check in WebSocket08FrameEncoder.encode(...).
Because msg.content() can not return null.
- Removed unnecessary null checks in ConcurrentHashMapV8.removeTreeNode(TreeNode<K,V>).
- Removed unnecessary null check in OioDatagramChannel.doReadMessages(List<Object>).
Because tmpPacket.getSocketAddress() always returns new SocketAddress instance.
- Removed unnecessary null check in OioServerSocketChannel.doReadMessages(List<Object>).
Because socket.accept() always returns new Socket instance.
- Pass Unpooled.buffer(0) instead of null inside CloseWebSocketFrame(boolean, int) constructor.
If we will pass null we will get NPE in super class constructor.
- Added throw new IllegalStateException in GlobalEventExecutor.awaitInactivity(long, TimeUnit) if it will be called before GlobalEventExecutor.execute(Runnable).
Because now we will get NPE. IllegalStateException will be better in this case.
- Fixed null check in OpenSslServerContext.setTicketKeys(byte[]).
Now we throw new NPE if byte[] is not null.
Result:
Added new null checks when it is necessary, removed unnecessary null checks and fixed some NPE problems.
Motivation:
Fix some typos in Netty.
Modifications:
- Fix potentially dangerous use of non-short-circuit logic in Recycler.transfer(Stack<?>).
- Removed double 'the the' in javadoc of EmbeddedChannel.
- Write to log an exception message if we can not get SOMAXCONN in the NetUtil's static block.
Motivation:
As a DatagramChannel supports to write to multiple remote peers we must not close the Channel once a IOException accours as this error may be only valid for one remote peer.
Modification:
Continue writing on IOException.
Result:
DatagramChannel can be used even after an IOException accours during writing.
Motivation:
Because of a missing return statement we may produce a NPE when try to fullfill the connect ChannelPromise when it was fullfilled before.
Modification:
Add missing return statement.
Result:
No more NPE.
Motivation:
When an exception is thrown during try to send DatagramPacket or SctpMessage a buffer may leak.
Modification:
Correctly handle allocated buffers in case of exception
Result:
No more leaks
Motivation:
When a bind fails AbstractBootstrap will use the GlobalEventExecutor to notify the ChannelPromise. We should use the EventLoop of the Channel if possible.
Modification:
Use EventLoop of the Channel if possible to use the correct Thread to notify and so guaranteer the right order of events.
Result:
Use the correct EventLoop for notification
