Motivation:
ResourceLeakDetector supports a parameter called maxActive. This parameter is used in attempt to limit the amount of objects which are being tracked for leaks at any given time, and generates an error log message if this limit is exceeded. This assumes that there is a relationship between leak sample rate and object lifetime for objects which are already being tracked. This relationship may appear to work in cases were there are a single leak record per object and those leak records live for the lifetime of the application but in general this relationship doesn't exist. The original motivation was to provide a limit for cases such as HashedWheelTimer to limit the number of instances which exist at any given time. This limit is not enforced in all circumstances in HashedWheelTimer (e.g. if the thread is a daemon) and can be implemented outside ResourceLeakDetector.
Modifications:
- Deprecate all methods which interact with maxActive in ResourceLeakDetectorFactory and ResourceLeakDetector
- Remove all logic related to maxActive in ResourceLeakDetector
- HashedWheelTimer implements its own logic to impose a limit and warn users if too many instances exists at any given time.
Result:
Fixes https://github.com/netty/netty/issues/6225.
Motivation:
We used various mocking frameworks. We should only use one...
Modifications:
Make usage of mocking framework consistent by only using Mockito.
Result:
Less dependencies and more consistent mocking usage.
Motivation:
When comparing MAC addresses searching for the best MAC address, if
locally-administered address (e.g., from a Docker container) is compared
against an empty MAC address, the empty MAC address will be marked as
preferred. In cases this is the only available MAC address, this leaves
Netty using a random machine ID instead of using a perfectly valid
machine ID from the locally-adminstered address.
Modifications:
This commit modifies the MAC address logic so that the empty MAC address
is not preferred over a locally-administered address. This commit also
simplifies the comparison logic here.
Result:
Empty MAC addresses will not be preferred over locally-administered
addresses thus permitting the default machine ID to be the
locally-adminstered MAC address if it is the only available MAC address.
Motivation:
codec-http2 couples the dependency tree state with the remainder of the stream state (Http2Stream). This makes implementing constraints where stream state and dependency tree state diverge in the RFC challenging. For example the RFC recommends retaining dependency tree state after a stream transitions to closed [1]. Dependency tree state can be exchanged on streams in IDLE. In practice clients may use stream IDs for the purpose of establishing QoS classes and therefore retaining this dependency tree state can be important to client perceived performance. It is difficult to limit the total amount of state we retain when stream state and dependency tree state is combined.
Modifications:
- Remove dependency tree, priority, and weight related items from public facing Http2Connection and Http2Stream APIs. This information is optional to track and depends on the flow controller implementation.
- Move all dependency tree, priority, and weight related code from DefaultHttp2Connection to WeightedFairQueueByteDistributor. This is currently the only place which cares about priority. We can pull out the dependency tree related code in the future if it is generally useful to expose for other implementations.
- DefaultHttp2Connection should explicitly limit the number of reserved streams now that IDLE streams are no longer created.
Result:
More compliant with the HTTP/2 RFC.
Fixes https://github.com/netty/netty/issues/6206.
[1] https://tools.ietf.org/html/rfc7540#section-5.3.4
Motivation:
A testing goof in 7c630fe introduced a binary incompatibility when the old Promise-specific `add` and `addAll` methods in PromiseCombiner were generalized to accept `Futures`.
Modification:
- Restore (but mark as `@Deprecated`) old PromiseCombiner methods.
- Fixed a couple minor documentation typos because sure why not.
Result:
`PromiseCombiner` is binary-compatible with previous versions of Netty.
Motivation:
When an empty hostname is used in DnsNameResolver.resolve*(...) it will never notify the future / promise. The root cause is that we not correctly guard against errors of IDN.toASCII(...) which will throw an IllegalArgumentException when it can not parse its input. That said we should also handle an empty hostname the same way as the JDK does and just use "localhost" when this happens.
Modifications:
- If the try to resolve an empty hostname we use localhost
- Correctly guard against errors raised by IDN.toASCII(...) so we will always noify the future / promise
- Add unit test.
Result:
DnsNameResolver.resolve*(...) will always notify the future.
Motivation:
Currently Netty does not wrap socket connect, bind, or accept
operations in doPrivileged blocks. Nor does it wrap cases where a dns
lookup might happen.
This prevents an application utilizing the SecurityManager from
isolating SocketPermissions to Netty.
Modifications:
I have introduced a class (SocketUtils) that wraps operations
requiring SocketPermissions in doPrivileged blocks.
Result:
A user of Netty can grant SocketPermissions explicitly to the Netty
jar, without granting it to the rest of their application.
Motivation:
Replacing System.err during Slf4JLoggerFactory construction is problematic as another class may optain the System.err reference before we set it back to the original value.
Modifications:
Remove code that temporary replaced System.err.
Result:
Fixes [#6212].
Motivation:
Pattern matching not necessary for number parsing.
Modification:
Removed pattern matching for number parsing and removed unnecessary toLowerCase() operation.
Result:
No static variable with pattern, removed unnecessary matching operation and toLowerCase() operation.
Motivation:
PlatformDependent* contains some methods that are not used and some other things that can be cleaned-up.
Modifications:
- Remove unused methods
- cleanup
Result:
Code cleanup.
Motivation:
The HttpProxyHandler is expected to be capable of issuing a valid CONNECT request for a tunneled connection to an IPv6 host.
Modifications:
- Correctly format the IPV6 address.
- Add unit tests
Result:
HttpProxyHandler works with IPV6 as well. Fixes [#6152].
Motivation:
When DefaultHttp2Connection removes a stream it iterates over all children and adds them as children to the parent of the stream being removed. This process may remove elements from the child map while iterating without using the iterator's remove() method. This is generally unsafe and may result in an undefined iteration.
Modifications:
- We should use the Iterator's remove() method while iterating over the child map
Result:
Fixes https://github.com/netty/netty/issues/6163
Motivation:
[#6153] reports an endless loop that existed in the Recycler, while this was fixed adding a few asserts to ensure this remains fixed is a good thing. Beside this we also should ensure this can not escape the constructor to avoid unsafe publication.
Modifications:
- Add asserts
- Fix unsafe publication
Result:
More correct code.
Motivation:
`scavengeSome()` has a corner case: when setting `cursor` to `head`, `this.prev` may point to the tail of the `WeakOrderQueue` linked list. Then it's possible that the following while loop will link the tail to the head, and cause endless loop.
I made a reproducer in 36522e7b72 . The unit test will just run forever. Unfortunately, I cannot change it to a unit test because it needs to add some codes to `scavengeSome` to control the execution flow.
Modification:
Set `prev` to null when setting `cursor` to `head` in `scavengeSome`
Result:
Fixes#6153.
Motivation:
InternalThreadLocalMap.arrayList returns a new ArrayList every time it's called that defeats the purpose of having a reusable ArrayList.
Modification:
Modified InternalThreadLocalMap.arrayList to create an ArrayList only if arrayList field is NULL.
Result:
InternalThreadLocalMap.arrayList now creates a reusable ArrayList only if arrayList field is NULL.
Motivation:
We used a MPSC queue in ThreadDeathWatcher and checked if it empty via isEmpty() from multiple threads if very unlucky. Depending on the implementation this is not safe and may even produce things like live-locks.
Modifications:
Change to use a MPMC queue.
Result:
No more risk to run into issues when multiple threads call watch(...) / unwatch(...) concurrently.
Motivation:
DefaultChannelId provides a regular expression which validates if a user provided MAC address is valid. This regular expression may allow invalid MAC addresses and also not allow valid MAC addresses.
Modifications:
- Introduce a MacAddressUtil#parseMac method which can parse and validate the MAC address at the same time. The regular expression check before hand is additional overhead if we have to parse the MAC address.
Result:
Fixes https://github.com/netty/netty/issues/6132.
Motivation:
`PromiseCombiner` is really handy, but it's not obvious how to use it from its existing documentation/method signatures.
Modification:
- Added javadoc comments to explain the theory of operation of `PromiseCombiner`.
- Generalized `PromiseCombiner` to work with `Futures` so it's clearer that the things for which it's listening won't be modified.
Result:
`PromiseCombiner` is easier to understand.
Motivation:
When profiling it is sometimes needed to still have the native library file avaible. We should allow to disable the explicit deletion and just delete it when the JVM stops.
This is related to #6110
Modifications:
Add io.netty.native.deleteLibAfterLoading system property which allows to disable the explicit delete after laoding
Result:
Possible to profile native libraries better.
Motivation:
In later Java8 versions our Atomic*FieldUpdater are slower then the JDK implementations so we should not use ours anymore. Even worse the JDK implementations provide for example an optimized version of addAndGet(...) using intrinsics which makes it a lot faster for this use-case.
Modifications:
- Remove methods that return our own Atomic*FieldUpdaters.
- Use the JDK implementations everywhere.
Result:
Faster code.
Motivation:
c2f4daa739 added a unit test but used a too small test timeout.
Modifications:
Increase timeout.
Result:
Test should have enough time to complete on the CI.
Motivation:
InternalLoggerFactory either sets a default logger factory
implementation based on the logging implementations on the classpath, or
applications can set a logger factory explicitly. If applications wait
too long to set the logger factory, Netty will have already set a logger
factory leading to some objects using one logging implementation and
other objets using another logging implementation. This can happen too
if the application tries to set the logger factory twice, which is
likely a bug in the application. Yet, the Javadocs for
InternalLoggerFactory warn against this saying that
InternalLoggerFactory#setLoggerFactory "should be called as early as
possible and shouldn't be called more than once". Instead, Netty should
guard against this.
Modications:
We replace the logger factory field with an atomic reference on which we
can do CAS operations to safely guard against it being set twice. We
also add an internal holder class that captures the static interface of
InternalLoggerFactory that can aid in testing.
Result:
The logging factory can not be set twice, and applications that want to
set the logging factory must do it before any Netty classes are
initialized (or the default logger factory will be set).
Motivation:
We need to ensure the tracked object can not be GC'ed before ResourceLeak.close() is called as otherwise we may get false-positives reported by the ResourceLeakDetector. This can happen as the JIT / GC may be able to figure out that we do not need the tracked object anymore and so already enqueue it for collection before we actually get a chance to close the enclosing ResourceLeak.
Modifications:
- Add ResourceLeakTracker and deprecate the old ResourceLeak
- Fix some javadocs to correctly release buffers.
- Add a unit test for ResourceLeakDetector that shows that ResourceLeakTracker has not the problems.
Result:
No more false-positives reported by ResourceLeakDetector when ResourceLeakDetector.track(...) is used.
Motivation:
Java9 will be released soon so we should ensure we can compile netty with Java9 and run all our tests. This will help to make sure Netty will be usable with Java9.
Modification:
- Add some workarounds to be able to compile with Java9, note that the full profile is not supported with Java9 atm.
- Remove some usage of internal APIs to be able to compile on java9
- Not support Alpn / Npn and so not run the tests when using Java9 for now. We will do a follow up PR to add support.
Result:
Its possible to build netty and run its testsuite with Java9.
Motivation:
42fba015ce changed the implemention of ResourceLeakDetector to improve performance. While this was done a branch was missed that can be removed. Beside this using a Boolean as value for the ConcurrentMap is sub-optimal as when calling remove(key, value) an uncessary instanceof check and cast is needed on each removal.
Modifications:
- Remove branch which is not needed anymore
- Replace usage of Boolean as value type of the ConcurrentMap and use our own special type which only compute hash-code one time and use a == operation for equals(...) to reduce overhead present when using Boolean.
Result:
Faster and cleaner ResourceLeakDetector.
Motivation:
Netty has a flag (io.netty.noUnsafe) for specifying to Netty to not be
unsafe. Yet, when initializing PlatformDependent0, Netty still tries to
be unsafe. For application that specify to Netty to not be unsafe and
run under a security manager, this can lead to an obnoxious (debug
level) stack trace. Since Netty was told not to be unsafe, Netty should
not try to be unsafe.
Modifications:
The initialization logic in PlatformDependent0 should take into account
that Netty was told not to be unsafe. This means that we need to
initialize PlatformDependent#IS_EXPLICIT_NO_UNSAFE as soon as possible,
before the static initializer for PlatformDependent0 has a chance to
run. Thus the following modifications are made:
- initialize PlatformDependent#IS_EXPLICIT_NO_UNSAFE before any other
code in PlatformDependent causes PlatformDependent0 to initialize
- expose the value of PlatformDependent#IS_EXPLICIT_NO_UNSAFE for
reading in PlatformDependent0
- take the value of PlatformDependent#IS_EXPLICIT_NO_UNSAFE into
account in PlatformDependent0
Result:
Netty does not try to be unsafe when told not to be unsafe.
Motivation:
For applications that set their own logger factory, they want that
logger factory to be the one logger factory. Yet, Netty eagerly
initializes this and then triggers initialization of other classes
before the application has had a chance to set its preferred logger
factory.
Modifications:
With this commit there are two key changes:
- Netty does not attempt to eagerly initialize the default logger
factory, only doing so if the application layer above Netty has not
already set a logger factory
- do not eagerly initialize unrelated classes from the logger factory;
while the motivation behind this was to initialize ThreadLocalRandom
as soon as possible in case it has to block reading from /dev/random,
this can be worked around for applications where it is problematic by
setting securerandom.source=file:/dev/urandom in their Java system
security policy (no, it is not less secure; do not even get me
started on myths about /dev/random)
Result:
Netty uses the logger factory that the application prefers, and does not
initialize unrelated classes.
Motivation:
PlatformDependent#getSystemClassLoader may throw a wide variety of exceptions based upon the environment. We should handle all exceptions and continue initializing the slow path if an exception occurs.
Modifications:
- Catch Throwable in cases where PlatformDependent#getSystemClassLoader is used
Result:
Fixes https://github.com/netty/netty/issues/6038
Motiviation:
We used ReferenceCountUtil.releaseLater(...) in our tests which simplifies a bit the releasing of ReferenceCounted objects. The problem with this is that while it simplifies stuff it increase memory usage a lot as memory may not be freed up in a timely manner.
Modifications:
- Deprecate releaseLater(...)
- Remove usage of releaseLater(...) in tests.
Result:
Less memory needed to build netty while running the tests.
Motivation:
00fc239995 introduced a change to HashedWheelTimerTest which attempted to wait for an explicit event notification until more timer events can be added. However HashedWheelTimer will execute the timer Runnable before removing it from the queue and decrementing the total count. This make it difficult for users to know when it is safe to add another timer task as the limit is approached.
Modifications:
- HashedWheelTimer should remove the timer Runnable before executing the task.
Result:
Users can more reliably add new timers when the limit is reached and HashedWheelTimerTest will no longer fail spuriously due to this race condition.
Motivation:
If a stream is not able to send any data (flow control window for the stream is exhausted) but has descendants who can send data then WeightedFairQueueByteDistributor may incorrectly modify the pseudo time and also double add the associated state to the parent's priority queue. The pseudo time should only be modified if a node is moved in the priority tree, and not if there happens to be no active streams in its descendent tree and a descendent is moved (e.g. removed from the tree because it wrote all data and the last data frame was EOS). Also the state objects for WeightedFairQueueByteDistributor should only appear once in any queue. If this condition is violated the pseudo time accounting would be biased at and assumptions in WeightedFairQueueByteDistributor would be invalidated.
Modifications:
- WeightedFairQueueByteDistributor#isActiveCountChangeForTree should not allow re-adding to the priority queue if we are currently processing a node in the distribution algorithm. The distribution algorithm will re-evaluate if the node should be re-added on the tail end of the recursion.
Result:
Fixes https://github.com/netty/netty/issues/5980
Motivation:
HashWheelTimerTest has busy/wait and sleep statements which are not necessary. We also depend upon a com.google.common.base.Supplier which isn't necessary.
Modifications:
- Remove buys wait loops and timeouts where possible
Result:
HashWheelTimerTest more explicit in verifying conditions and less reliant on wait times.
Motivation:
If the rate at which new timeouts are created is very high and the created timeouts are not cancelled, then the JVM can crash because of out of heap space. There should be a guard in the implementation to prevent this.
Modifications:
The constructor of HashedWheelTimer now takes an optional max pending timeouts parameter beyond which it will reject new timeouts by throwing RejectedExecutionException.
Result:
After this change, if the max pending timeouts parameter is passed as constructor argument to HashedWheelTimer, then it keeps a track of pending timeouts that aren't yet expired or cancelled. When a new timeout is being created, it checks for current pending timeouts and if it's equal to or greater than provided max pending timeouts, then it throws RejectedExecutionException.
Motivation:
PlatformDependent0 should not be referenced directly when sun.misc.Unsafe is unavailable.
Modifications:
Guard byteArrayBaseOffset with hasUnsafe check.
Result:
PlatformDependent can be initialized when sun.misc.Unsafe is unavailable.
Motivation:
ResourceLeakDetector shows two main problems, racy access and heavy lock contention.
Modifications:
This PR fixes this by doing two things:
1. Replace the sampling counter with a ThreadLocalRandom. This has two benefits.
First, it makes the sampling ration no longer have to be a power of two. Second,
it de-noises the continuous races that fight over this single value. Instead,
this change uses slightly more CPU to decide if it should sample by using TLR.
2. DefaultResourceLeaks need to be kept alive in order to catch leaks. The means
by which this happens is by a singular, doubly-linked list. This creates a
large amount of contention when allocating quickly. This is noticeable when
running on a multi core machine.
Instead, this uses a concurrent hash map to keep track of active resources
which has much better contention characteristics.
Results:
Better concurrent hygiene. Running the gRPC QPS benchmark showed RLD taking about
3 CPU seconds for every 1 wall second when runnign with 12 threads.
There are some minor perks to this as well. DefaultResourceLeak accounting is
moved to a central place which probably has better caching behavior.
Motivation:
PlatformDependent has a hash code algorithm which utilizes UNSAFE for performance reasons. This hash code algorithm must also be consistent with CharSequence objects that represent a collection of ASCII characters. In order to make the UNSAFE versions and CharSequence versions the endianness should be taken into account. However the big endian code was not correct in a few places.
Modifications:
- Correct bugs in PlatformDependent class related to big endian ASCII hash code computation
Result:
Fixes https://github.com/netty/netty/issues/5925
