Motivation
AbstractReferenceCounted and AbstractReferenceCountedByteBuf contain
duplicate logic for managing the volatile refcount in an optimized and
consistent manner, which increased in complexity in #8583. It's possible
to extract this into a common helper class now that all access is via an
AtomicIntegerFieldUpdater.
Modifications
- Move duplicate logic into a shared ReferenceCountUpdater class
- Incorporate some additional simplification for the most common single
increment/decrement cases (fewer checks/operations)
Result
Less code duplication, better encapsulation of the "non-trivial"
internal volatile refcount manipulation
Motivation:
DefaultPromise requires an EventExecutor which provides the thread to notify listeners on and this EventExecutor can never change. We can remove the code that supported the possibility of a changing the executor as this is not possible anymore.
Modifications:
- Remove constructor which allowed to construct a *Promise without an EventExecutor
- Remove extra state
- Adjusted SslHandler and ProxyHandler for new code
Result:
Fixes https://github.com/netty/netty/issues/8517.
Motivation:
PooledByteBufAllocator uses a PoolThreadCache per Thread that allocates / deallocates to minimize the performance overhead. This PoolThreadCache is trimmed after X allocations to free up buffers that are not allocated for a long time. This works out quite well when the app continues to allocate but fails if the app stops to allocate frequently (for whatever reason) and so a lot of memory is wasted and not given back to the arena / freed.
Modifications:
- Add a ThreadExecutorMap that offers multiple methods that wrap Runnable / ThreadFactory / Executor and allow to call ThreadExecutorMap.currentEventExecutor() to get the current executing EventExecutor for the calling Thread.
- Use these methods in the constructors of our EventExecutor implementations (which also covers the EventLoop implementations)
- Add io.netty.allocator.cacheTrimIntervalMillis system property which can be used to specify a fixed rate / interval on which we should try to trim the PoolThreadCache for a EventExecutor that allocates.
- Add PooledByteBufAllocator.trimCurrentThreadCache() to allow the user to trim the cache of the calling thread manually.
- Add testcases
- Introduce FastThreadLocal.getIfExists()
Result:
Allow to better / more frequently trim PoolThreadCache and so give back memory to the area / system.
Motivation:
We dont use ObjectCleaner in our FastThreadLocal anymore so we also dont need to take special care to store it there anymore.
Modifications:
Remove code that is not needed anymore.
Result:
Code cleanup.
Motivation:
GlobalEventExecutor does already provide all guarantees of OrderedEventExecutor so it should implement it.
Modifications:
Let GlobalEventExecutor implement OrderedEventExecutor.
Result:
Make it more clear how execution order is handled in GlobalEventExecutor.
Motivation:
This counter is very useful in order to monitor Netty without having every ByteBufAllocator in the JVM
Modification:
Expose the value of DIRECT_MEMORY_COUNTER as we are already doing for DIRECT_MEMORY_LIMIT.
We are returning -1 in case that DIRECT_MEMORY_COUNTER is not available.
Result:
Be able to get the amount of direct memory used.
Motivation:
We had a typo in NativeLibraryLoader debug log message which could misslead the user.
Modifications:
Fix typo to correctly state java.library.path
Result:
Correct and less confusing log message
Motivation:
2bb9f64e16 introduced a change which made it possible to use different shaded versions of netty-tcnative on the classpath. This only partly worked as we did not correctly handled the case when os / arch is part of the library name (which is the case when netty-tcnative-boringssl-static is used with the uber jar).
Modifications:
- If patching the ID failed we retry again with the os / arch stripped
- Add unit tests to verify that patching ID now works with and without os / arch as suffix.
Result:
Using multiple shaded version of netty-tcnative-boringssl-static on MacOS works.
Motivation:
We should run a CI job using J9 to ensure netty also works when using different JVMs.
Modifications:
- Adjust PooledByteBufAllocatorTest to be able to complete faster when using a JVM which takes longer when joining Threads (this seems to be the case with J9).
Result:
Be able to run CI against J9.
Motivation:
PromiseCombiner is not thread-safe and even assumes all added Futures are using the same EventExecutor. This is kind of fragile as we do not enforce this. We need to enforce this contract to ensure it's safe to use and easy to spot concurrency problems.
Modifications:
- Add new contructor to PromiseCombiner that takes an EventExecutor and deprecate the old non-arg constructor.
- Check if methods are called from within the EventExecutor thread and if not fail
- Correctly dispatch on the right EventExecutor if the Future uses a different EventExecutor to eliminate concurrency issues.
Result:
More safe use of PromiseCombiner + enforce correct usage / contract.
Motivation:
https://github.com/netty/netty/pull/8866 added support for calling Iterator.remove() but did not add a testcase.
Modifications:
Add testcase to ensure removal works.
Result:
Better test-coverage.
Motivation:
As ActiveMQ project using netty, we want to make use of this class, unfortunately the iterator on values(), seems to not support remove method, even so the delegated iterator does. Currently we have to clone and modify this class locally albeit a one line change is needed, it would be ideal if netty could allow remove, then removing the need to maintain a clone.
Modifications:
* remove throws UnsupportedOperationException, and instead call remove method on delegated iterator
Result:
Be able to call Iterator.remove() for the values.
Motivation:
When users' /tmp is noexec, NativeLibraryLoader logs a message informing
them how to fix the problem by setting a system property. However, if
Netty has been shaded that message will tell them to set the un-shaded
system property name, which won't work.
Modifications:
Change the code to let shading tools rename the native.workdir property
name reference within user-visible log messages.
Notably, debug logs were _not_ changed, as there's many debug statements
including a variety of property names. Fixing them would be a much more
invasive change and have limited benefit.
Result:
The users will see the correctly-named system property to set if they
are using a noexec /tmp.
Motivation:
When we fail a call to PromiseCombiner.finish(...) because of a null argument we must not update the internal state before throwing.
Modifications:
- First do the null check and only after we validated that the argument is not null update the internal state
- Add test case.
Modifications:
Do not mess up internal state of PromiseCombiner when finish(...) is called with a null argument.
Result:
After your change, what will change.
Motivation:
We can remove some properties for which we introduced replacements.
Modifications:
io.netty.buffer.bytebuf.checkAccessible, io.netty.leakDetectionLevel, org.jboss.netty.tryUnsafe properties removed
Result:
Code cleanup
Motivation:
We can just use Objects.requireNonNull(...) as a replacement for ObjectUtil.checkNotNull(....)
Modifications:
- Use Objects.requireNonNull(...)
Result:
Less code to maintain.
Motivation:
Just was looking through code and found 1 interesting place DateFormatter.tryParseMonth that was not very effective, so I decided to optimize it a bit.
Modification:
Changed DateFormatter.tryParseMonth method. Instead of invocation regionMatch() for every month - compare chars one by one.
Result:
DateFormatter.parseHttpDate method performance improved from ~3% to ~15%.
Benchmark (DATE_STRING) Mode Cnt Score Error Units
DateFormatter2Benchmark.parseHttpHeaderDateFormatter Sun, 27 Jan 2016 19:18:46 GMT thrpt 6 4142781.221 ± 82155.002 ops/s
DateFormatter2Benchmark.parseHttpHeaderDateFormatter Sun, 27 Dec 2016 19:18:46 GMT thrpt 6 3781810.558 ± 38679.061 ops/s
DateFormatter2Benchmark.parseHttpHeaderDateFormatterNew Sun, 27 Jan 2016 19:18:46 GMT thrpt 6 4372569.705 ± 30257.537 ops/s
DateFormatter2Benchmark.parseHttpHeaderDateFormatterNew Sun, 27 Dec 2016 19:18:46 GMT thrpt 6 4339785.100 ± 57542.660 ops/s
Motivation
As pointed out by @91he in
https://github.com/netty/netty/pull/8595#issuecomment-459181794, there
is a remaining bug in LocationAwareSlf4JLogger following the updates
done in #8595. The logging methods which take a varargs message
parameter array should format using MessageFormatter.arrayFormat rather
than MessageFormatter.format.
Modifications
Change varargs param methods in LocationAwareSlf4JLogger to use
MessageFormatter.arrayFormat and extend unit test to cover these cases.
Results
Correct log output when logging messages with > 2 parameters when using
LocationAwareSlf4JLogger.
Motivation:
If there are no listeners attached to the promise when full-filling it we do not need to schedule a task to notify.
Modifications:
- Don't schedule a task if there is nothing to notify.
- Add unit tests.
Result:
Fixes https://github.com/netty/netty/issues/8795.
Motivation:
To conform to the CharSequence interface we need to return an empty CharSequence when start == end index and a subSequence is requested.
Modifications:
- Correctly handle the case where start == end
- Add unit test
Result:
Fix https://github.com/netty/netty/issues/8796.
Motivation:
We can use lambdas now as we use Java8.
Modification:
use lambda function for all package, #8751 only migrate transport package.
Result:
Code cleanup.
Motivation:
As netty 4.x supported Java 6 we had various if statements to check for java versions < 8. We can remove these now.
Modification:
Remove unnecessary if statements that check for java versions < 8.
Result:
Cleanup code.
Motivation:
We need to update to a new checkstyle plugin to allow the usage of lambdas.
Modifications:
- Update to new plugin version.
- Fix checkstyle problems.
Result:
Be able to use checkstyle plugin which supports new Java syntax.
* Decouble EventLoop details from the IO handling for each transport to allow easy re-use of code and customization
Motiviation:
As today extending EventLoop implementations to add custom logic / metrics / instrumentations is only possible in a very limited way if at all. This is due the fact that most implementations are final or even package-private. That said even if these would be public there are the ability to do something useful with these is very limited as the IO processing and task processing are very tightly coupled. All of the mentioned things are a big pain point in netty 4.x and need improvement.
Modifications:
This changeset decoubled the IO processing logic from the task processing logic for the main transport (NIO, Epoll, KQueue) by introducing the concept of an IoHandler. The IoHandler itself is responsible to wait for IO readiness and process these IO events. The execution of the IoHandler itself is done by the SingleThreadEventLoop as part of its EventLoop processing. This allows to use the same EventLoopGroup (MultiThreadEventLoupGroup) for all the mentioned transports by just specify a different IoHandlerFactory during construction.
Beside this core API change this changeset also allows to easily extend SingleThreadEventExecutor / SingleThreadEventLoop to add custom logic to it which then can be reused by all the transports. The ideas are very similar to what is provided by ScheduledThreadPoolExecutor (that is part of the JDK). This allows for example things like:
* Adding instrumentation / metrics:
* how many Channels are registered on an SingleThreadEventLoop
* how many Channels were handled during the IO processing in an EventLoop run
* how many task were handled during the last EventLoop / EventExecutor run
* how many outstanding tasks we have
...
...
* Implementing custom strategies for choosing the next EventExecutor / EventLoop to use based on these metrics.
* Use different Promise / Future / ScheduledFuture implementations
* decorate Runnable / Callables when submitted to the EventExecutor / EventLoop
As a lot of functionalities are folded into the MultiThreadEventLoopGroup and SingleThreadEventLoopGroup this changeset also removes:
* AbstractEventLoop
* AbstractEventLoopGroup
* EventExecutorChooser
* EventExecutorChooserFactory
* DefaultEventLoopGroup
* DefaultEventExecutor
* DefaultEventExecutorGroup
Result:
Fixes https://github.com/netty/netty/issues/8514 .
Motivation:
Custom Netty ThreadLocalRandom and ThreadLocalRandomProvider classes are no longer needed and can be removed.
Modification:
Remove own ThreadLocalRandom
Result:
Less code to maintain
Motivation:
PlatformDependent.newConcurrentHashMap() is no longer needed so it could be easily removed and new ConcurrentHashMap<>() inlined instead of invoking PlatformDependent.newConcurrentHashMap().
Modification:
Use ConcurrentHashMap provided by the JDK directly.
Result:
Less code to maintain.
Motivation:
No need to initialize charsets from the string. We can take already allocated charset from StandardCharsets class.
Modification:
Replace Charset.forName("US-ASCII") with StandardCharsets.US_ASCII.
Removed Charset[] values() method and internal static variable as it was used only in tests.
Result:
Reuse what the JDK provides
Motivation:
Simplify code with newer Java API. It also reduce levels of indirection, but I don't
think we can gain any visible performance improvements out of this.
Modifications:
Replace Collection.newSetFromMap(new ConcurrentHashMap()) with ConcurrentHashMap.newKeySet().
Result:
Use Java8 APIs.
Motivation:
We can use the diamond operator these days.
Modification:
Use diamond operator whenever possible.
Result:
More modern code and less boiler-plate.
Motivation:
Since Java 7 we can automatically close resources in try () construction.
Modification:
Changed all try catches in the code with autoclose try (resource)
Result:
Less boiler-plate
Motivation:
After switching to Java 8 we no longer need LongCounter and LongAdderCounter. We can directly replace them with LongAdder.
Modification:
Removed LongCounter and LongAdderCounter classes.
Result:
Less code to maintain
Motivation:
Netty uses own Integer.compare and Long.compare methods. Since Java 7 we can use Java implementation instead.
Modification:
Remove own implementation
Result:
Less code to maintain
Motivation:
IntergerHolder was left from some old days and not used anymore.
Modification:
Remove IntergerHolder from the codebase.
Result:
Removed unused code
Motivation:
The concurrent set is present in Java 8 and above so we can use it instead of own implementation.
Modification:
io.netty.utik.internal.ConcurrentSet replaced with ConcurrentHashMap.newKeySet().
Result:
Less code to maintain.
Motivation:
Incrementing two variables in sync is not necessary when only one will do.
Modifications:
- Remove `j` from `for` loop and replace with `i`.
- Add more unit testing scenarios to cover changed code.
Results:
Unnecessary variable removed.
Motivation:
We should try removing all FastThreadLocals for the Thread before we notify the termination. future. The user may block on the future and once it unblocks the JVM may terminate and start unloading classes.
Modifications:
Remove all FastThreadLocals for the Thread before notify termination future.
Result:
Fixes https://github.com/netty/netty/issues/6596.
Motivation:
executeAfterEventLoopIteration is an Unstable API and isnt used in Netty. We should remove it to reduce complexity.
Changes:
This reverts commit 77770374fb.
Result:
Simplify implementation / cleanup.
Motivation:
In windows if the project is in a path that contains whitespace,
resources cannot be accessed and tests fail.
Modifications:
Adds ResourcesUtil.java in netty-common. Tests use ResourcesUtil.java to access a resource.
Result:
Being able to build netty in a path containing whitespace
Motivation
#8563 highlighted race conditions introduced by the prior optimistic
update optimization in 83a19d5650. These
were known at the time but considered acceptable given the perf
benefit in high contention scenarios.
This PR proposes a modified approach which provides roughly half the
gains but stronger concurrency semantics. Race conditions still exist
but their scope is narrowed to much less likely cases (releases
coinciding with retain overflow), and even in those
cases certain guarantees are still assured. Once release() returns true,
all subsequent release/retains are guaranteed to throw, and in
particular deallocate will be called at most once.
Modifications
- Use even numbers internally (including -ve) for live refcounts
- "Final" release changes to odd number (equivalent to refcount 0)
- Retain still uses faster getAndAdd, release uses CAS loop
- First CAS attempt uses non-volatile read
- Thread.yield() after a failed CAS provides a net gain
Result
More (though not completely) robust concurrency semantics for ref
counting; increased latency under high contention, but still roughly
twice as fast as the original logic. Bench results to follow
Motivation:
We did miss to use MessageFormatter inside LocationAwareSlf4jLogger and so {} was not correctly replaced in log messages when using slf4j.
This regression was introduced by afe0767e9c.
Modifications:
- Make use of MessageFormatter
- Add unit test.
Result:
Fixes https://github.com/netty/netty/issues/8483.
Motivation:
We can change from using compareAndSet to addAndGet, which emits a different CPU instruction on x86 (CMPXCHG to XADD) when count direct memory usage. This instruction is cheaper in general and so produce less overhead on the "happy path". If we detect too much memory usage we just rollback the change before throwing the Error.
Modifications:
Replace compareAndSet(...) with addAndGet(...)
Result:
Less overhead when tracking direct memory.
