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.
Motivation:
We should allow adjustment of the leak detecting sampling interval when in SAMPLE mode.
Modifications:
Added new int property io.netty.leakDetection.samplingInterval
Result:
Be able to consume changes made by the user.
Motivation:
There is a racy UnsupportedOperationException instead because the task removal is delegated to MpscChunkedArrayQueue that does not support removal. This happens with SingleThreadEventExecutor that overrides the newTaskQueue to return an MPSC queue instead of the LinkedBlockingQueue returned by the base class such as NioEventLoop, EpollEventLoop and KQueueEventLoop.
Modifications:
- Catch the UnsupportedOperationException
- Add unit test.
Result:
Fix#8475
Motivation:
allLeaks is to store the DefaultResourceLeak. When we actually use it, the key is DefaultResourceLeak, and the value is actually a meaningless value.
We only care about the keys of allLeaks and don't care about the values. So Set is more in line with this scenario.
Using Set as a container is more consistent with the definition of a container than Map.
Modification:
Replace allLeaks with set. Create a thread-safe set using 'Collections.newSetFromMap(new ConcurrentHashMap<DefaultResourceLeak<?>, Boolean>()).'
Motivation:
HWT does not support anything smaller then 1ms so we should make it clear that this is the case.
Modifications:
Log a warning if < 1ms is used.
Result:
Less suprising behaviour.
Motivation:
In netty we use our own max direct memory limit that can be adjusted by io.netty.maxDirectMemory but we do not take this in acount when maxDirectMemory() is used. That will lead to non optimal configuration of PooledByteBufAllocator in some cases.
This came up on stackoverflow:
https://stackoverflow.com/questions/53097133/why-is-default-num-direct-arena-derived-from-platformdependent-maxdirectmemory
Modifications:
Correctly respect io.netty.maxDirectMemory and so configure PooledByteBufAllocator correctly by default.
Result:
Correct value for max direct memory.
Motivation:
There are currently many more places where this could be used which were
possibly not considered when the method was added.
If https://github.com/netty/netty/pull/8388 is included in its current
form, a number of these places could additionally make use of the same
BYTE_ARRAYS threadlocal.
There's also a couple of adjacent places where an optimistically-pooled
heap buffer is used for temp byte storage which could use the
threadlocal too in preference to allocating a temp heap bytebuf wrapper.
For example
https://github.com/netty/netty/blob/4.1/buffer/src/main/java/io/netty/buffer/ByteBufUtil.java#L1417.
Modifications:
Replace new byte[] with PlatformDependent.allocateUninitializedArray()
where appropriate; make use of ByteBufUtil.getBytes() in some places
which currently perform the equivalent logic, including avoiding copy of
backing array if possible (although would be rare).
Result:
Further potential speed-up with java9+ and appropriate compile flags.
Many of these places could be on latency-sensitive code paths.
Motivation:
trackedObject != null gives no guarantee that trackedObject remains reachable. This may cause problems related to premature finalization: false leak detector warnings.
Modifications:
Add private method reachabilityFence0 that works on JDK 8 and can be factored out into PlatformDependent. Later, it can be swapped for the real Reference.reachabilityFence.
Result:
No false leak detector warnings in future versions of JDK.
Motivation:
DefaultResourceLeak.toString() did include the wrong value for duplicated records.
Modifications:
Include the correct value.
Result:
Correct toString() implementation.
Motivation:
Java since version 6 has the wrapper for the ConcurrentHashMap that could be created via Collections.newSetFromMap(map). So no need to create own ConcurrentSet class. Also, since netty plans to switch to Java 8 soon there is another method for that - ConcurrentHashMap.newKeySet().
For now, marking this class @deprecated would be enough, just to warn users who use netty's ConcurrentSet. After switching to Java 8 ConcurrentSet should be removed and replaced with ConcurrentHashMap.newKeySet().
Modification:
ConcurrentSet deprecated.
Motivation:
Seems like IntegerHolder counterHashCode field is the very old legacy field that is no longer used. Should be marked as deprecated and removed in the future versions.
Modification:
IntegerHolder class, InternalThreadLocalMap.counterHashCode() and InternalThreadLocalMap.setCounterHashCode(IntegerHolder counterHashCode) are now deprecated.
Motivation:
When a X509TrustManager is used while configure the SslContext the JDK automatically does some extra checks during validation of provided certs by the remote peer. We should do the same when our native implementation is used.
Modification:
- Automatically wrap a X509TrustManager and so do the same validations as the JDK does.
- Add unit tests.
Result:
More consistent behaviour. Fixes https://github.com/netty/netty/issues/6664.
Motivation:
The Epoll transport checks to see if there are any scheduled tasks
before entering epoll_wait, and resets the timerfd just before.
This causes an extra syscall to timerfd_settime before doing any
actual work. When scheduled tasks aren't added frequently, or
tasks are added with later deadlines, this is unnecessary.
Modification:
Check the *deadline* of the peeked task in EpollEventLoop, rather
than the *delay*. If it hasn't changed since last time, don't
re-arm the timer
Result:
About 2us faster on gRPC RTT 50pct latency benchmarks.
Before (2 runs for 5 minutes, 1 minute of warmup):
```
50.0%ile Latency (in nanos): 64267
90.0%ile Latency (in nanos): 72851
95.0%ile Latency (in nanos): 78903
99.0%ile Latency (in nanos): 92327
99.9%ile Latency (in nanos): 119691
100.0%ile Latency (in nanos): 13347327
QPS: 14933
50.0%ile Latency (in nanos): 63907
90.0%ile Latency (in nanos): 73055
95.0%ile Latency (in nanos): 79443
99.0%ile Latency (in nanos): 93739
99.9%ile Latency (in nanos): 123583
100.0%ile Latency (in nanos): 14028287
QPS: 14936
```
After:
```
50.0%ile Latency (in nanos): 62123
90.0%ile Latency (in nanos): 70795
95.0%ile Latency (in nanos): 76895
99.0%ile Latency (in nanos): 90887
99.9%ile Latency (in nanos): 117819
100.0%ile Latency (in nanos): 14126591
QPS: 15387
50.0%ile Latency (in nanos): 61021
90.0%ile Latency (in nanos): 70311
95.0%ile Latency (in nanos): 76687
99.0%ile Latency (in nanos): 90887
99.9%ile Latency (in nanos): 119527
100.0%ile Latency (in nanos): 6351615
QPS: 15571
```
* Log the correct line-number when using SLF4j with netty if possible.
Motivation:
At the moment we do not log the correct line number in many cases as it will log the line number of the logger wrapper itself. Slf4j does have an extra interface that can be used to filter out these nad make it more usable with logging wrappers.
Modifications:
Detect if the returned logger implements LocationAwareLogger and if so make use of its extra methods to be able to log the correct origin of the log request.
Result:
Better logging when using slf4j.
Motivation:
In Java8 and earlier we used reflection to replace the used key set if not otherwise told. This does not work on Java9 and later without special flags as its not possible to call setAccessible(true) on the Field anymore.
Modifications:
- Use Unsafe to instrument the Selector with out special set when sun.misc.Unsafe is present and we are using Java9+.
Result:
NIO transport produce less GC on Java9 and later as well.
Motivation:
In Java8 and earlier we used reflection to detect if unaligned access is supported. This fails in Java9 and later as we would need to change the accessible level of the method.
Lucky enough we can use Unsafe directly to read the content of the static field here.
Modifications:
Add special handling for detecting if unaligned access is supported on Java9 and later which does not fail due jigsaw.
Result:
Better and more correct detection on Java9 and later.
Motivation:
At the moment we will just assume the correct version of log4j2 is used when we find it on the classpath. This may lead to an AbstractMethodError at runtime. We should not use log4j2 if the version is not correct.
Modifications:
Check on class loading if we can use Log4J2 or not.
Result:
Fixes#8217.
Motivation:
Log4J2Logger had some code-duplication with AbstractInternalLogger
Modifications:
Reuse AbstractInternaLogger.EXCEPTION_MESSAGE in Log4J2Logger and so remove some code-duplication
Result:
Less duplicated code.
* We should be able to use the ByteBuffer cleaner on java8 (and earlier versions) even if sun.misc.Unsafe is not present.
Motivation:
At the moment we have a hard dependency on sun.misc.Unsafe to use the Cleaner on Java8 and earlier. This is not really needed as we can still use pure reflection if sun.misc.Unsafe is not present.
Modifications:
Refactor Cleaner6 to fallback to pure reflection if sun.misc.Unsafe is not present on system.
Result:
More timely releasing of direct memory on Java8 and earlier when sun.misc.Unsafe is not present.
Motivation:
f77891cc17 changed slightly how we detect if we should prefer direct buffers or not but did miss to also take this into account when logging.
Modifications:
Fix branch for log message to reflect changes in f77891cc17.
Result:
Correct logging.
Motivation:
There was a race condition between the task submitter and task executor threads such that the last Runnable submitted may not get executed.
Modifications:
The bug was fixed by checking the task queue and state in the task executor thread after it saw the task queue was empty.
Result:
Fixes#8230
Motivation:
We should prefer direct buffers whenever we can use the cleaner even if sun.misc.Unsafe is not present.
Modifications:
Correctly prefer direct buffers in all cases.
Result:
More correct code.
Motivation:
CleanerJava9 currently fails whever a SecurityManager is installed. We should make use of AccessController.doPrivileged(...) so the user can give it the correct rights.
Modifications:
Use doPrivileged(...) when needed.
Result:
Fixes https://github.com/netty/netty/issues/8201.
Motivation:
Recycler may produce a NPE when the same object is recycled multiple times from different threads.
Modifications:
- Check if the id has changed or if the Stack became null and if so throw an IllegalStateException
- Add unit test
Result:
Fixes https://github.com/netty/netty/issues/8220.
* Try to monkey-patch library id when shading is used and we are on MacOS / OSX.
Motivation:
ea4c315b45 did ensure we support using multiple versions of the same shaded native library but the user still needed to run install_name_tool -id on MacOS to ensure the ID is unique.
This is kind of error prone and also means that the shading itself would need to be done on MacOS / OSX.
This is related to https://github.com/netty/netty/issues/7272.
Modifications:
- Monkey patch the shaded native lib on MacOS to ensure the id is unique while unpacking it to the tempory location.
Result:
Easier way of using shaded native libs in netty.
Motivation:
Java9 and later does the safepoint polling by itself so there is not need for us to do it.
Modifications:
Check for java version before doing manual safepoint polling.
Result:
Less custom code and less overhead when using java9 and later. Fixes https://github.com/netty/netty/issues/8122.
Motivation:
We do not correctly check for previous calles of setUncancellable() in getNow() which may result in ClassCastException as we incorrectly return the internally UNCANCELLABLE object and not null if setUncancellable() we as called before.
Modifications:
Correctly check for UNCANCELLABLE and add unit test.
Result:
Fixes https://github.com/netty/netty/issues/8135.
Motivation:
We incorrectly calculated the length that was used for our for loop in AsciiString.indexOf(...). This lead to a possible ArrayIndexOutOfBoundsException.
Modifications:
- Not include the start in the length calculation
- Add unit test.
Result:
Fixes https://github.com/netty/netty/issues/8112.
Motivation:
Users should not see a scary log message when Netty is initialized if
Netty configuration explicitly disables unsafe. The log message that
produces this warning was previously guarded but by recent refactoring
a bug was introduced inside the guard helper method.
Modifications:
This commit brings back the guard against the scary log message if
unsafe is explicitly disabled.
Result:
No log message is produced when unsafe is unavailable because Netty was
told to not look for it.
Relates https://github.com/netty/netty/pull/5624, https://github.com/netty/netty/pull/6696
Motivation:
ObjectCleaner does start a Thread to handle the cleaning of resources which leaks into the users application. We should not use it in netty itself to make things more predictable.
Modifications:
- Remove usage of ObjectCleaner and use finalize as a replacement when possible.
- Clarify javadocs for FastThreadLocal.onRemoval(...) to ensure its clear that remove() is not guaranteed to be called when the Thread completees and so this method is not enough to guarantee cleanup for this case.
Result:
Fixes https://github.com/netty/netty/issues/8017.
Motivation:
I'm not sure if trivial changes like this are interesting :-) But I
noticed that the PlatformDependent.maxDirectMemory0() method is called
twice unnecessarily during static initialization (on the default path at
least).
Modifications:
Use constant MAX_DIRECT_MEMORY already set to the same value instead of
calling maxDirectMemory0() again.
Result:
A surely imperceivable reduction in operations performed at startup.
Motivation
There is a cost to concatenating strings and calling methods that will be wasted if the Logger's level is not enabled.
Modifications
Check if Log level is enabled before producing log statement. These are just a few cases found by RegEx'ing in the code.
Result
Tiny bit more efficient code.
Motivation:
We should allow to schedule tasks with a delay up to Long.MAX_VALUE as we did pre 4.1.25.Final.
Modifications:
Just ensure we not overflow and put the correct max limits in place when schedule a timer. At worse we will get a wakeup to early and then schedule a new timeout.
Result:
Fixes https://github.com/netty/netty/issues/7970.
Motivation:
On J9 / OpenJ9 netty initializes this value with 64M, even the direct accessible memory is actually unbounded.
Modifications:
Skip usage of VM.maxDirectMemory() on J9 / OpenJ9
Result:
More correct direct memory limit detection. Fixes#7654.
Motivation:
We did not guard against the case of calling malloc(0) when creating a ByteBuffer without a Cleaner. The problem is that malloc(0) can have different behaviour, it either return a null-pointer or a valid pointer that you can pass to free.
The real problem arise if Unsafe.allocateMemory(0) returns 0 and we use it as the memoryAddress of the ByteBuffer. The problem here is that native libraries test for 0 and handle it as a null-ptr. This is for example true in SSL.bioSetByteBuffer(...) which would throw a NPE when 0 is used as memoryAddress and so produced errors during SSL usage.
Modifications:
- Always allocate 1 byte as minimum (even if we ask for an empty buffer).
- Add unit test.
Result:
No more errors possible because of malloc(0).
Motivation:
When a buffer is over-released, the current error message of `IllegalReferenceCountException` is `refCnt: XXX, increment: XXX`, which is confusing. The correct message should be `refCnt: XXX, decrement: XXX`.
Modifications:
Pass `-decrement` to create `IllegalReferenceCountException`.
Result:
The error message will be `refCnt: XXX, decrement: XXX` when a buffer is over-released.
Motivation:
On z/OS netty initializes this value with 64M, even the direct accessible memory is actually unbounded.
Modifications:
Skip usage of VM.maxDirectMemory() on z/OS.
Result:
More correct direct memory limit detection. Fixes https://github.com/netty/netty/issues/7654.
Motivation:
Using a very huge delay when calling schedule(...) may cause an Selector error when calling select(...) later on. We should gaurd against such a big value.
Modifications:
- Add guard against a very huge value.
- Added tests.
Result:
Fixes [#7365]
Motivation:
A FastThreadLocal instance currently occupies 2 slots of InternalThreadLocalMap of every thread. Actually for a FastThreadLocalThread, it does not need to store cleaner flags of FastThreadLocal instances. Besides, using BitSet to store cleaner flags is also better for space usage.
Modification:
Use BitSet to optimize space usage of FastThreadLocal.
Result:
Avoid unnecessary slot occupancy. Cleaner flags are now stored into a BitSet.
Motivation:
When trying to cleanup WeakOrderQueue by the ObjectCleaner we end up in an endless loop which will cause the ObjectCleaner to be not able to cleanup any other resources anymore.This bug was introduced by 6eb9674bf5.
Modifications:
Correctly update link while cleanup
Result:
Fixes https://github.com/netty/netty/issues/7877
Motivation:
The bounds checking for AsciiString#indexOf and AsciiString#lastIndexOf is not correct and may lead to ArrayIndexOutOfBoundsException.
Modifications:
- Correct the bounds checking for AsciiString#indexOf and AsciiString#lastIndexOf
Result
Fixes https://github.com/netty/netty/issues/7863
Motivation:
Finer granularity when configuring CorsHandler, enabling different policies for different origins.
Modifications:
The CorsHandler has an extra constructor that accepts a List<CorsConfig> that are evaluated sequentially when processing a Cors request
Result:
The changes don't break backwards compatibility. The extra ctor can be used to provide more than one CorsConfig object.
Motivation:
Minor performance optimisation that prevents thread from blocking due to task not having been added to queue. Discussed #7815.
Modification:
add task to the queue before starting the thread.
Result:
No additional tests.
* NetUtil valid IP methods to accept CharSequence
Motivation:
NetUtil has methods to determine if a String is a valid IP address. These methods don't rely upon String specific methods and can use CharSequence instead.
Modifications:
- Use CharSequence instead of String for the IP validator methods.
- Avoid object allocation in AsciiString#indexOf(char,int) and reduce
byte code
Result:
No more copy operation required if a CharSequence exists.
Motivation:
HttpProxyHandler uses `NetUtil#toSocketAddressString` to compute
CONNECT url and Host header.
The url is correct when the address is unresolved, as
`NetUtil#toSocketAddressString` will then use
`getHoststring`/`getHostname`. If the address is already resolved, the
url will be based on the IP instead of the hostname.
There’s an additional minor issue with the Host header: default port
443 should be omitted.
Modifications:
* Introduce NetUtil#getHostname
* Introduce HttpUtil#formatHostnameForHttp to format an
InetSocketAddress to
HTTP format
* Change url computation to favor hostname instead of IP
* Introduce HttpProxyHandler ignoreDefaultPortsInConnectHostHeader
parameter to ignore 80 and 443 ports in Host header
Result:
HttpProxyHandler performs properly when connecting to a resolved address
Motivation:
We missed to correctly record the stacktrace of the creation of an ResourceLeak record. This could either have the effect to log the wrote stacktrace for creation or not log a stacktrace at all if the object was dropped on the floor after it was created.
Modifications:
Correctly create a Record on creation of the object.
Result:
Fixes https://github.com/netty/netty/issues/7781.
Motivation:
We recently introduced ObjectCleaner which can be used to ensure some cleanup action is done once an object becomes weakable reachable. We should use this in Recycler.WeakOrderQueue to reduce the overhead of using a finalizer() (which will cause the GC to process it two times).
Modifications:
Replace finalizer() usage with ObjectCleaner
Result:
Fixes [#7343]
Motivation:
We dont protect from overflow and so the timer may fire too early if a large timeout is used.
Modifications:
Add overflow guard and a test.
Result:
Fixes https://github.com/netty/netty/issues/7760.
Motivation:
It is not clear why Unsafe is unavailable when it is explicitly
disabled, or when Netty thinks it is running on Android.
Modification:
Change the "has" fields and methods to be causes. A null cause
means Unsafe is present. This catches all possible reason why
Unsafe might not be available.
Result:
Easier to debug Netty start up when logging cannot be turned on.
Motivation:
DefaultPromise's internal state depends upon specific Signal objects. These Signal objects can be used externally which causes the DefaultPromise object API to not function correct and state to become corrupted.
Modifications:
- DefaultPromise shouldn't depend upon Signal for its internal state
Result:
Fixes https://github.com/netty/netty/issues/7707
Motivation:
The Recycler currently retains 32k objects per thread by default. The Recycler is used in more than just one place and may result in large amounts of memory bloat if spikes of traffic are observed.
Modifications:
- Reduce the Recyclers default capacity from 32k to 4k.
Result:
- Lower default capacity of the Recycler and less memory retained.
Motivation:
Some java binaries include android classes on their classpath, even
if they aren't actually android. When this is true, `Unsafe` no
longer works, disabling the Epoll functionality. A sample case is
for binaries that use the j2objc library.
Modifications:
Check the `java.vm.name` instead of the classpath. Numerous
Google-internal Android libraries / binaries check this property
rather than the class path.
It is believed this is safe and works with bother ART and Dalvik
VMs, safe for Robolectric, and j2objc.
Results:
Unusually built java server binaries can still use Netty Epoll.
Motivation:
Currently if user call set/remove/set/remove many times, it will create multiple cleaner task for same index. It may cause OOM due to long live thread will have more and more task in LIVE_SET.
Modification:
Add flag to avoid recreating tasks.
Result:
Only create 1 clean task. But use more space of indexedVariables.
Motivation:
Reflective setAccessible(true) will produce scary warnings on the console when using java9+, while netty still works. That said users may feel uncomfortable with these warnings, we should not try to do it by default when using java9+.
Modifications:
Add io.netty.tryReflectionSetAccessible system property which controls if setAccessible(...) will be used. By default it will bet set to false when using java9+.
Result:
Fixes [#7254].
Motivation:
The methods implement io.netty.util.concurrent.Future#cancel(boolean mayInterruptIfRunning) which actually ignored the param mayInterruptIfRunning.We need to add comments for the `mayInterruptIfRunning` param.
Modifications:
Add comments for the `mayInterruptIfRunning` param.
Result:
People who call the `cancel` method will be more clear about the effect of `mayInterruptIfRunning` param.
Motivation:
The ObjectCleanerThread must be a daemon thread as otherwise we may block the JVM from exit. By using a daemon thread we basically give the same garantees as the JVM when it comes to cleanup of resources (as the GC threads are also daemon threads and the CleanerImpl uses a deamon thread as well in Java9+).
Modifications:
Change ObjectCleanThread to be a daemon thread.
Result:
JVM shutdown will always be able to complete. Fixed [#7617].
Motivation:
In environments with a security manager, the reflective access to get the reference to
Throwable#addSuppressed can cause issues that result in Netty failing to load. The main
motivation in this pull request is to remove the use of reflection to prevent issues in
these environments.
Modifications:
ThrowableUtil no longer uses Class#getDeclaredMembers to get the Method that references
Throwable#addSuppressed and instead guards the call to Throwable#addSuppressed with a
Java version check.
Additionally, a annotation was added that suppresses the animal sniffer java16 signature
check on the given method. The benefit of the annotation is that it limits the exclusion
of Throwable to just the ThrowableUtil class and has string text indicating the reason
for suppressing the java16 signature check.
Result:
Netty no longer requires the use of Class#getDeclaredMethod for ThrowableUtil and will
work in environments restricted by a security manager without needing to grant reflection
permissions.
Fixes#7614
Motivation:
In a few classes, Netty starts a thread and then sets the context classloader of these threads
to prevent classloader leaks. The Thread#setContextClassLoader method is a privileged method in
that it requires permissions to be executed when there is a security manager in place. Unless
these calls are wrapped in a doPrivileged block, they will fail in an environment with a security
manager and restrictive policy in place.
Modifications:
Wrap the calls to Thread#setContextClassLoader in a AccessController#doPrivileged block.
Result:
After this change, the threads can set the context classloader without any errors in an
environment with a security manager and restrictive policy in place.
Motivation:
Usages of HttpResponseStatus may result in more object allocation then necessary due to not looking for cached objects and the AsciiString parsing method not being used due to CharSequence method being used instead.
Modifications:
- HttpResponseDecoder should attempt to get the HttpResponseStatus from cache instead of allocating a new object
- HttpResponseStatus#parseLine(CharSequence) should check if the type is AsciiString and redirect to the AsciiString parsing method which may not require an additional toString call
- HttpResponseStatus#parseLine(AsciiString) can be optimized and doesn't require and may not require object allocation
Result:
Less allocations when dealing with HttpResponseStatus.
Motivation:
ObjectCleaner inovkes a Runnable which may execute user code (FastThreadLocal#onRemoval) and therefore exceptions maybe thrown. If an exception is thrown the cleanup thread will exit prematurely and we may never finish cleaning up which will result in leaks.
Modifications:
- ObjectCleaner should suppress exceptions and continue cleaning
Result:
ObjectCleaner will reliably clean despite exceptions being thrown.
Motivation:
ObjectCleaner polls a ReferenceQueue which will block indefinitely. However it is possible there is a race condition between the live set of objects being empty due to the WeakReference being cleaned/cleared and polling the queue. If this situation occurs the cleanup thread may never unblock if no more objects are added to the live set, and may result in an application's failure to gracefully close.
Modifications:
- ReferenceQueue.remove should use a timeout to compensate for the race condition, and avoid dead lock
Result:
No more dead lock in ObjectCleaner when polling the ReferenceQueue.
Motivation:
FastThreadLocal#set calls isIndexedVariableSet to determine if we need to register with the cleaner, but the set(InternalThreadLocalMap, V) method will also internally do this check so we can share code and only do the check a single time.
Modifications:
- extract code from set(InternalThreadLocalMap, V) so it can be called externally to determine if a new item was created
Result:
Less code duplication in FastThreadLocal#set.
Motivation:
e329ca1 introduced the user of ObjectCleaner in FastThreadLocal but we missed the case to register our cleaner task if FastThreadLocal.set was called only.
Modifications:
- Use ObjectCleaner also when FastThreadLocal.set is used.
- Add test case.
Result:
ObjectCleaner is always used.
Motivation:
Allow pre-computing calculation of the constants for compiler where it could be.
Similar fix in OpenJDK: [1].
Modifications:
- Use parentheses.
- Simplify static initialization of `BYTE2HEX_*` arrays in `StringUtil`.
Result:
Less bytecode, possible faster calculations at runtime.
[1] https://bugs.openjdk.java.net/browse/JDK-4477961
Motivation:
There is no guarantee that FastThreadLocal.onRemoval(...) is called if the FastThreadLocal is used by "non" FastThreacLocalThreads. This can lead to all sort of problems, like for example memory leaks as direct memory is not correctly cleaned up etc.
Beside this we use ThreadDeathWatcher to check if we need to release buffers back to the pool when thread local caches are collected. In the past ThreadDeathWatcher was used which will need to "wakeup" every second to check if the registered Threads are still alive. If we can ensure FastThreadLocal.onRemoval(...) is called we do not need this anymore.
Modifications:
- Introduce ObjectCleaner and use it to ensure FastThreadLocal.onRemoval(...) is always called when a Thread is collected.
- Deprecate ThreadDeathWatcher
- Add unit tests.
Result:
Consistent way of cleanup FastThreadLocals when a Thread is collected.
Motivation:
We should remove the WeakOrderedQueue from the WeakHashMap directly if possible and only depend on the semantics of the WeakHashMap if there is no other way for us to cleanup it.
Modifications:
Override onRemoval(...) to remove the WeakOrderedQueue if possible.
Result:
Less overhead and quicker collection of WeakOrderedQueue for some cases.
Motivation:
When doStartThread throws an exception, e.g. due to the actual executor being depleted of threads and throwing in its rejected execution handler, the STEE ends up in started state anyway. If we try to execute another task in this executor, it will be queued but the thread won't be started anymore and the task will linger forever.
Modifications:
- Ensure we not update the internal state if the startThread() method throws.
- Add testcase
Result:
Fixes [#7483]
Motivation:
In our Recycler implementation we store a reference to the current Thread in the Stack that is stored in a FastThreadLocal. The Stack itself is referenced in the DefaultHandle itself. A problem can arise if a user stores a Reference to an Object that holds a reference to the DefaultHandle somewhere and either not remove the reference at all or remove it very late. In this case the Thread itself can not be collected as its still referenced in the Stack that is referenced by the DefaultHandle.
Modifications:
- Use a WeakReference to store the reference to the Thread in the Stack
- Add a test case
Result:
Ensure a Thread can be collected in a timely manner in all cases even if it used the Recycler.
Motivation:
ThreadDeathWatcher and GlobalEventExecutor may create and start a new thread from various other threads and so inherit the classloader. We need to ensure we not inherit to allow recycling the classloader.
Modifications:
Use Thread.setContextClassLoader(null) to ensure we not hold a strong reference to the classloader and so not leak it.
Result:
Fixes [#7290].
Motivation:
We dont need to use the ThreadDeathWatcher if we use a FastThreadLocalThread for which we wrap the Runnable and ensure we call FastThreadLocal.removeAll() once the Runnable completes.
Modifications:
- Dont use a ThreadDeathWatcher if we are sure we will call FastThreadLocal.removeAll()
- Add unit test.
Result:
Less overhead / running theads if you only allocate / deallocate from FastThreadLocalThreads.
Motivation:
OSGI and other enviroments may not allow to even load Unsafe which will lead to an NoClassDefFoundError when trying to access it. We should guard against this.
Modifications:
Catch NoClassDefFoundError when trying to load Unsafe.
Result:
Be able to use netty with a strict OSGI config.
