Motivation:
Some usages of findNextPositivePowerOfTwo assume that bounds checking is taken care of by this method. However bounds checking is not taken care of by findNextPositivePowerOfTwo and instead assert statements are used to imply the caller has checked the bounds. This can lead to unexpected non power of 2 return values if the caller is not careful and thus invalidate any logic which depends upon a power of 2.
Modifications:
- Add a safeFindNextPositivePowerOfTwo method which will do runtime bounds checks and always return a power of 2
Result:
Fixes https://github.com/netty/netty/issues/5601
Motivation:
When Unpooled.wrappedBuffer(...) is called with an array of ByteBuf with length >= 2 and the first ByteBuf is not readable it will result in double releasing of these empty buffers when release() is called on the returned buffer.
Modifications:
- Ensure we only wrap readable buffers.
- Add unit test
Result:
No double release of buffers.
Motivation:
retainSlice() currently does not unwrap the ByteBuf when creating the ByteBuf wrapper. This effectivley forms a linked list of ByteBuf when it is only necessary to maintain a reference to the unwrapped ByteBuf.
Modifications:
- retainSlice() and retainDuplicate() variants should only maintain a reference to the unwrapped ByteBuf
- create new unit tests which generally verify the retainSlice() behavior
- Remove unecessary generic arguments from AbstractPooledDerivedByteBuf
- Remove unecessary int length member variable from the unpooled sliced ByteBuf implementation
- Rename the unpooled sliced/derived ByteBuf to include Unpooled in their name to be more consistent with the Pooled variants
Result:
Fixes https://github.com/netty/netty/issues/5582
Motivation:
At the moment the Recyler is very sensitive to allocation bursts which means that if there is a need for X objects for only one time these will most likely end up in the Recycler and sit there forever as the normal workload only need a subset of this number.
Modifications:
Add a ratio which sets how many objects should be pooled for each new allocation. This allows to slowly increase the number of objects in the Recycler while not be to sensitive for bursts.
Result:
Less unused objects in the Recycler if allocation rate sometimes bursts.
Motivation:
SwappedByteBuf.retainedSlice(...) did not return a retained buffer.
Modifications:
Correctly delegate to retainedSlice(..) calls.
Result:
Correctly return retained slice.
Motivation:
Because of a bug we missed to include the first PoolSubpage when collection metrics.
Modifications:
- Correctly include all subpages
- Add unit test
Result:
Correctly include all subpages
Motivation:
In order to prevent a regression, add test case for a bug that caused a CompositeByteBuf to not release its components.
Modifications:
Add a test case that asserts a CompositeByteBuf's component buffers have indeed been released.
Result:
AbstractCompositeByteBuf gains a test case that will prevent future regressions.
Allow users of Netty to plug in their own leak detector for the purpose
of instrumentation.
Motivation:
We are rolling out a large Netty deployment and want to be able to
track the amount of leaks we're seeing in production via custom
instrumentation. In order to achieve this today, I had to plug in a
custom `ByteBufAllocator` into the bootstrap and have it initialize a
custom `ResourceLeakDetector`. Due to these classes mostly being marked
`final` or having private or static methods, a lot of the code had to
be copy-pasted and it's quite ugly.
Modifications:
* I've added a static loader method for the `ResourceLeakDetector` in
`AbstractByteBuf` that tries to instantiate the class passed in via the
`-Dio.netty.customResourceLeakDetector`, otherwise falling back to the
default one.
* I've modified `ResourceLeakDetector` to be non-final and to have the
reporting broken out in to methods that can be overridden.
Result:
You can instrument leaks in your application by just adding something
like the following:
```java
public class InstrumentedResourceLeakDetector<T> extends
ResourceLeakDetector<T> {
@Monitor("InstanceLeakCounter")
private final AtomicInteger instancesLeakCounter;
@Monitor("LeakCounter")
private final AtomicInteger leakCounter;
public InstrumentedResourceLeakDetector(Class<T> resource) {
super(resource);
this.instancesLeakCounter = new AtomicInteger();
this.leakCounter = new AtomicInteger();
}
@Override
protected void reportTracedLeak(String records) {
super.reportTracedLeak(records);
leakCounter.incrementAndGet();
}
@Override
protected void reportUntracedLeak() {
super.reportUntracedLeak();
leakCounter.incrementAndGet();
}
@Override
protected void reportInstancesLeak() {
super.reportInstancesLeak();
instancesLeakCounter.incrementAndGet();
}
}
```
Motivation:
See #82.
Modifications:
- Added `isText` to validate if the given ByteBuf is compliant with the specified charset.
- Optimized for UTF-8 and ASCII. For other cases, `CharsetDecoder.decoder` is used.
Result:
Users can validate ByteBuf with given charset.
Motivation:
We need to first store a reference to the wrapped buffer before recycle the AbstractPooledDerivedByteBuf instance. This is needed as otherwise it is possible that the same AbstractPooledDerivedByteBuf is again obtained and init(...) is called before we actually have a chance to call release(). This leads to call release() on the wrong buffer.
Modifications:
Store a reference to the wrapped buffer before call recycle and call release on the previous stored reference.
Result:
Always release the correct wrapped buffer when deallocate the AbstractPooledDerivedByteBuf.
Motivation:
If the user uses unsafe direct buffers with no cleaner we can use Unsafe.reallocateMemory(...) as optimization when we need to expand the buffer.
Modifications:
Use Unsafe.relocateMemory(...) in UnpooledUnsafeNoCleanerDirectByteBuf.
Result:
Less expensive expanding of buffers.
Motivation:
Using the Cleaner to release the native memory has a few drawbacks:
- Cleaner.clean() uses static synchronized internally which means it can be a performance bottleneck
- It put more load on the GC
Modifications:
Add new buffer implementations that can be enabled with a system flag as optimizations. In this case no Cleaner is used at all and the user must ensure everything is always released.
Result:
Less performance impact by direct buffers when need to be allocated and released.
Motivation:
Unsafe offers a method to set memory to a specific value. This can be used to implement an optimized version of setZero(...) and writeZero(...)
Modifications:
Add implementation for all Unsafe*ByteBuf implementations.
Result:
Faster setZero(...) and writeZero(...)
Motivation:
At the moment the user is responsible to increase the writer index of the composite buffer when a new component is added. We should add some methods that handle this for the user as this is the most popular usage of the composite buffer.
Modifications:
Add new methods that autoamtically increase the writerIndex when buffers are added.
Result:
Easier usage of CompositeByteBuf.
Motivation:
We missed to override a few methods and so some actions on the ByteBuf failed.
Modifications:
- Override all methods
- Add unit tests to ensure all is fixed.
Result:
All *LeakAware*ByteBuf have correct implementations
Motivation:
Recycler.recycle(...) should not be used anymore and be replaced by Handle.recycle().
Modifications:
Mark it as deprecated and update usage.
Result:
Correctly document deprecated api.
Motivation:
Some tests in PooledByteBufAllocatorTest are blocking on a CountDownLatch. We should use a timeout on these tests so these will not block forever on a failure.
Modifications:
Add timeout param to @Test annotation
Result:
Have sane timeouts on tests.
Motivation:
DefaultByteBufHolder.equals(...) and hashCode() should be implemented so it works correctly with instances that share the same content.
Modifications:
Add implementations and a unit-test.
Result:
Have correctly working equals(...) and hashCode() method
Related: #4333#4421#5128
Motivation:
slice(), duplicate() and readSlice() currently create a non-recyclable
derived buffer instance. Under heavy load, an application that creates a
lot of derived buffers can put the garbage collector under pressure.
Modifications:
- Add the following methods which creates a non-recyclable derived buffer
- retainedSlice()
- retainedDuplicate()
- readRetainedSlice()
- Add the new recyclable derived buffer implementations, which has its
own reference count value
- Add ByteBufHolder.retainedDuplicate()
- Add ByteBufHolder.replace(ByteBuf) so that..
- a user can replace the content of the holder in a consistent way
- copy/duplicate/retainedDuplicate() can delegate the holder
construction to replace(ByteBuf)
- Use retainedDuplicate() and retainedSlice() wherever possible
- Miscellaneous:
- Rename DuplicateByteBufTest to DuplicatedByteBufTest (missing 'D')
- Make ReplayingDecoderByteBuf.reject() return an exception instead of
throwing it so that its callers don't need to add dummy return
statement
Result:
Derived buffers are now recycled when created via retainedSlice() and
retainedDuplicate() and derived from a pooled buffer
Motivation:
PooledByteBufAllocatorTest.testNumThreadCachesWithNoDirrectArenas() had a race as it just used LockSupport.parkNanos(). We should better use a CountdownLatch and so be sure we really have init everything.
Modifications:
Replace LockSupport.parkNanos(...) with CountdownLatch usage
Result:
No more race in test.
Motivation:
We called deallocationsHuge.decrement() but it needs to be increment()
Modifications:
Replace decrement() with increment()
Result:
Correct metrics.
Motivation:
Often users either need to read or write CharSequences to a ByteBuf. We should add methods for this to ByteBuf as we can do some optimizations for this depending on the implementation.
Modifications:
Add setCharSequence, writeCharSequence, getCharSequence and readCharSequence
Result:
Easier reading / writing of CharSequence with ByteBuf.
Motivation:
Reduce nag warnings when compiling, make it easier for IDEs to display what's deprecated.
Modifications:
Added @Deprecated in a few places
Result:
No more warnings.
Motivation:
We lately added ByteBuf.isReadOnly() which allows to detect if a buffer is read-only or not. We should add ByteBuf.asReadOnly() to allow easily access a read-only version of a buffer.
Modifications:
- Add ByteBuf.asReadOnly()
- Deprecate Unpooled.unmodifiableBuffer(Bytebuf)
Result:
More consistent api.
Motivation:
When FixedCompositeByteBuf was constructed with new ByteBuf[0] and IndexOutOfboundsException was thrown.
Modifications:
Fix constructor
Result:
No more exception
Motivation:
We should not cache the SwappedByteBuf in AbstractByteBuf to reduce the memory footprint.
Modifications:
Not cache the SwappedByteBuf.
Result:
Less memory footprint.
Motivation:
Some ByteBuf implementations do not override all necessary methods,
which can lead to potentially sub-optimal behavior.
Also, SlicedByteBuf does not perform the range check correctly due to
missing overrides.
Modifications:
- Add missing overrides
- Use unwrap() instead of direct member access in derived buffers for
consistency
- Merge unwrap0() into unwrap() using covariant return type
- Deprecate AbstractDerivedByteBuf and its subtypes, because they were
not meant to be public
Result:
Correctness
Motivation:
ByteBuf.readBytes(...) uses Unpooled.buffer(...) internally which will use a heap ByteBuf and also not able to make use of the allocator which may be pooled. We should better make use of the allocator.
Modifications:
Use the allocator for thenew buffer.
Result:
Take allocator into account when copy bytes.
Motiviation:
Sometimes it is useful to dump the status of the PooledByteBufAllocator and log it. Doing this is currently a bit cumbersome as the user needs to basically iterate through all the metrics and compose the String. we would better provide an easy way to do this.
Modification:
Add dumpStats() method.
Result:
Easier to get a view into the status of the allocator.
Motivation:
PoolChunkList.allocate(...) should return false without the need to walk all the contained PoolChunks when the requested capacity is larger then the capacity that can be allocated out of the PoolChunks in respect to the minUsage() and maxUsage() of the PoolChunkList.
Modifications:
Precompute the maximal capacity that can be allocated out of the PoolChunks that are contained in the PoolChunkList and use this to fast return from the allocate(...) method if an allocation capacity larger then that is requested.
Result:
Faster detection of allocations that can not be handled by the PoolChunkList and so faster allocations in general via the PoolArena.
Motivation:
To better understand how much memory is used by Netty for ByteBufs it is useful to understand how many bytes are currently active (allocated) per PoolArena.
Modifications:
- Add PoolArenaMetric.numActiveBytes()
Result:
The user is able to get better insight into the PooledByteBufAllocator.
Motivation:
To make it easier to understand PoolChunk and PoolArena we should cleanup duplicated code.
Modifications:
- Move reused code into methods
- Use Math.max(...)
Result:
Cleaner code and easier to understand.
Motivation:
When doing a normal allocation in PoolArena we also tried to allocate out of the PoolChunkList that only contains completely full PoolChunks. This makes no sense as these are full anyway so an allocation will never work here and just gives a perf hit as we need to walk the whole list of PoolChunks in the list.
Modifications:
Not try to allocate from PoolChunkList that only contains full PoolChunks
Result:
Faster allocation times when a new PoolChunk must be created.
Motivation:
We should better use Math utilities as these are intrinsics. This is a cleanup for ea3ffb8536.
Modifications:
Use Math utilities.
Result:
Cleaner code and use of intrinsics.
Motivation:
When a PoolChunk needs to get moved to the previous PoolChunkList because of the minUsage / maxUsage constraints we always just moved it one level which is incorrect and so could lead to have PoolChunks in the wrong PoolChunkList (in respect to their minUsage / maxUsage settings). This then could have the effect that PoolChunks are not released / freed in a timely fashion and so.
Modifications:
- Correctly move PoolChunks between PoolChunkLists, which includes moving it multiple "levels".
- Add unit test
Result:
Correctlty move the PoolChunk to PoolChunkList when it is freed, even if its multiple layers.
Motivation:
The PoolChunkList.minUsage() and maxUsage() needs to take special action to translate Integer.MIN_VALUE / MAX_VALUE as these are used internal for tail and head of the linked-list structure.
Modifications:
- Correct the minUsage() and maxUsage() methods.
- Add unit test.
Result:
Correct metrics
Motivation:
Sometimes it is useful to allow to disable the leak detection of buffers if the UnpooledByteBufAllocator is used. This is for example true if the app wants to leak buffers into user code but not want to put the burden on the user to always release the buffer.
Modifications:
Add another constructor to UnpooledByteBufAllocator that allows to completely disable leak-detection for all buffers that are allocator out of the UnpooledByteBufAllocator.
Result:
It's possible to disable leak-detection when the UnpooledByteBufAllocator is used.
Motivation:
We should only increment the metric for the huge / normal allocation after it is done. Also we should only decrement once deallocate.
Modifications:
- Move increment after the allocation.
- Fix deallocation metric and move it after deallocation
Result:
More correct metrics.
Motivation:
PoolThreadCache includes the wrong value when throwing a IllegalArgumentException because of freeSweepAllocationThreshold.
Modifications:
Use the correct value.
Result:
Correct exception message.
Motivation:
The method setBytes creates temporary heap buffer when source buffer is read-only.
But this temporary buffer is not used correctly and may lead to data corruption.
This problem occurs when target buffer is pooled and temporary buffer
arrayOffset() is not zero.
Modifications:
Use correct arrayOffset when calling PlatformDependent.copyMemory.
Unit test was added to test this case.
Result:
Setting buffer content works correctly when target is pooled buffer and source
is read-only ByteBuffer.
Motivation:
We also need to add synchronization when access fields to ensure we see the latest updates.
Modifications:
Add synchronization when read fields that are written concurrently.
Result:
Ensure correct visibility of updated.
Motivation:
See #1811
Modifications:
Add LineEncoder and LineSeparator
Result:
The user can use LineEncoder to write a String with a line separator automatically
Motivation:
We had some double spacing in the methods which should be removed to keep things consistent.
Modifications:
Remove redundant spaces.
Result:
Cleaner / consistent coding style.
Motivation:
My previous commit b88a980482 introduced a flawed unit test,
that executes an assertion in a different thread than the test thread.
If this assertion fails, the test doesn't fail.
Modifications:
Replace the assertion by a proper workaround.
Result:
More correct unit test
Motivation:
Circular assignment of arenas to thread caches can lead to less than optimal
mappings in cases where threads are (frequently) shutdown and started.
Example Scenario:
There are a total of 2 arenas. The first two threads performing an allocation
would lead to the following mapping:
Thread 0 -> Arena 0
Thread 1 -> Arena 1
Now, assume Thread 1 is shut down and another Thread 2 is started. The current
circular assignment algorithm would lead to the following mapping:
Thread 0 -> Arena 0
Thread 2 -> Arena 0
Ideally, we want Thread 2 to use Arena 1 though.
Presumably, this is not much of an issue for most Netty applications that do all
the allocations inside the eventloop, as eventloop threads are seldomly shut down
and restarted. However, applications that only use the netty-buffer package
or implement their own threading model outside the eventloop might suffer from
increased contention. For example, gRPC Java when using the blocking stub
performs some allocations outside the eventloop and within its own thread pool
that is dynamically sized depending on system load.
Modifications:
Implement a linear scan algorithm that assigns a new thread cache to the arena
that currently backs the fewest thread caches.
Result:
Closer to ideal mappings between thread caches and arenas. In order to always
get an ideal mapping, we would have to re-balance the mapping whenever a thread
dies. However, that's difficult because of deallocation.
Motivation:
The statistic counters PoolArena.(allocationsTiny|allocationsSmall) are
not protected by a per arena lock, but by a per size class lock. Thus,
two concurrent allocations of different size (class) could lead to a
race and ultimately to wrong statistics.
Modifications:
Use a thread-safe LongCounter instead of a plain long data type.
Result:
Fewer data races.
Motivation:
See #3321
Modifications:
1. Add CharsetUtil.encoder/decoder() methods
2. Deprecate CharsetUtil.getEncoder/getDecoder() methods
Result:
Users can use new CharsetUtil.encoder/decoder() to specify error actions
Motivation:
Utility methods in ByteBufUtil to writeUtf8 and writeAscii expect a buffer to already be allocated. If the user does not have a buffer allocated they have to know details of the encoding in order to know the size of the buffer to allocate.
Modifications:
- Add writeUtf8 and writeAscii which take a ByteBufAllocator and allocate a ByteBuf of the correct size for the user
Result:
ByteBufUtil methods which are easier to use if the user doesn't already have a ByteBuf.
Motivation:
[#4842] introduced 4 new methods but missed to implement advanced leak detection for these.
Modifications:
Correctly implement advanced leak detection for these methods.
Result:
Advanced leak detection works for all methods as expected.
Motivation
See ##3229
Modifications:
Add methods with position independent FileChannel calls to ByteBuf and its subclasses.
Results:
The user can use these new methods to read/write ByteBuff without updating FileChannel's position.
Motivation:
f750d6e36c added support for surrogates in the writeUtf8 conversion. However exceptions are thrown if invalid input is detected, but the JDK (and slow path of writeUtf8) uses a replacement character and does not throw. We should behave the same way.
Modificiations:
- Don't throw in ByteBufUtil.writeUtf8, and instead use a replacement character consistent with the JDK
Result:
ByteBufUtil.writeUtf8 behavior is consistent with the JDK UTF_8 conversion.
Motivation:
We missed to take the byte[] into account when try to access the bytes and so produce a segfault.
Modifications:
Correctly pass the byte[] in.
Result:
No more segfault.
Motivation:
The current interface for CompositeByteBuf.addComponent is not clear under what conditions ownership is transferred when addComponent is called. There should be a well defined behavior so that users can ensure that no leaks occur.
Modifications:
- CompositeByteBuf.addComponent should always assume reference count ownership
Result:
Users that call CompositeByteBuf.addComponent do not have to independently check if the buffer's ownership has been transferred and if not independently release the buffer.
Fixes https://github.com/netty/netty/issues/4760
Motivation:
CompositeByteBuf only implemented simple resource leak detection and how it was implemented was completly different to the way it was for ByteBuf. The other problem was that slice(), duplicate() and others would not return a resource leak enabled buffer.
Modifications:
- Proper implementation for all level of resource leak detection for CompositeByteBuf
Result:
Proper resource leak detection for CompositeByteBuf.
Motivation:
We missed reporting *LE operations when AdvancedLeakAwareByteBuf was used. This could lead to incomplete access reports.
Modifications:
Correctly record access for *LE operations.
Result:
Correct leak reports.
Motivation:
AdvancedLeakAwareByteBuf.forEachByteDesc(...) called recordLeakNonRefCountingOperation() two times which resulted in incorrect leak detection reports.
Modifications:
Remove duplicated call to recordLeakNonRefCountingOperation()
Result:
Correct leak detection results
Motivation:
There are a few buffer leaks related to how Unpooled.wrapped and Base64.encode is used.
Modifications:
- Fix usages of Bas64.encode to correct leaks
- Clarify interface of Unpooled.wrapped* to ensure reference count ownership is clearly defined.
Result:
Reference count code is more clearly defined and less leaks are possible.
Motivation:
Javadoc reports errors about invalid docs.
Modifications:
Fix some errors reported by javadoc.
Result:
A lot of javadoc errors are fixed by this patch.
Motivation:
There are some wrong links and tags in javadoc.
Modifications:
Fix the wrong links and tags in javadoc.
Result:
These links will work correctly in javadoc.
Motivation:
UTF-16 can not represent the full range of Unicode characters, and thus has the concept of Surrogate Pair (http://unicode.org/glossary/#surrogate_pair) where 2 16-bit code units can be used to represent the missing characters. ByteBufUtil.writeUtf8 is currently does not support this and is thus incomplete.
Modifications:
- Add support for surrogate pairs in ByteBufUtil.writeUtf8
Result:
ByteBufUtil.writeUtf8 now supports surrogate pairs and is correctly converting to UTF-8.
Motivation:
We missed to check if the dst is ready only before using unsafe to copy data into it which lead to data-corruption. We need to ensure we respect ready only ByteBuffer.
Modifications:
- Correctly check if the dst is ready only before copy data into it in UnsafeByteBufUtil
- Also make it work for buffers that are not direct and not have an array
Result:
No more data corruption possible if the dst buffer is readonly and unsafe buffer implementation is used.
Motivation:
Initialisation of the ByteBufUtil class, a class frequently used is
delayed because a significant number of String operations is performed to
fill a HEXDUMP_ROWPREFIXES array. This array also sticks to the Strings
forever.
It is quite likely that applications never use the hexdump facility.
Modification:
Moved the static initialisation and references to a static inner class.
This delays initialisation (and memory usage) until actually needed.
The API is kept as is.
Result:
Faster startup time, less memory usage for most netty using applications.
As discussed in #3209, this PR adds Little Endian accessors
to ByteBuf and descendants.
Corresponding accessors were added to UnsafeByteBufUtil,
HeapByteBufferUtil to avoid calling `reverseBytes`.
Deprecate `order()`, `order(buf)` and `SwappedByteBuf`.
Motivation:
The method setBytes did not work correctly because read-only ByteBuffer
does not allow access to its underlying array.
Modifications:
New case was added for ByteBuffer's that are not direct and do not have an array.
These must be handled by copying the data into a temporary array. Unit test was
added to test this case.
Result:
It is now possible to use read-only ByteBuffer as the source
for the setBytes method.
Motivation:
The HTTP/2 RFC (https://tools.ietf.org/html/rfc7540#section-8.1.2) indicates that header names consist of ASCII characters. We currently use ByteString to represent HTTP/2 header names. The HTTP/2 RFC (https://tools.ietf.org/html/rfc7540#section-10.3) also eludes to header values inheriting the same validity characteristics as HTTP/1.x. Using AsciiString for the value type of HTTP/2 headers would allow for re-use of predefined HTTP/1.x values, and make comparisons more intuitive. The Headers<T> interface could also be expanded to allow for easier use of header types which do not have the same Key and Value type.
Motivation:
- Change Headers<T> to Headers<K, V>
- Change Http2Headers<ByteString> to Http2Headers<CharSequence, CharSequence>
- Remove ByteString. Having AsciiString extend ByteString complicates equality comparisons when the hash code algorithm is no longer shared.
Result:
Http2Header types are more representative of the HTTP/2 RFC, and relationship between HTTP/2 header name/values more directly relates to HTTP/1.x header names/values.
Motivation:
Modulo operations are slow, we can use bitwise operation to detect if resource leak detection must be done while sampling.
Modifications:
- Ensure the interval is a power of two
- Use bitwise operation for sampling
- Add benchmark.
Result:
Faster sampling.
Motivation:
Fix a race condition that was introduced by f18990a8a5 that could lead to a NPE when allocate from the PooledByteBufAllocator concurrently by many threads.
Modifications:
Correctly synchronize on the PoolSubPage head.
Result:
No more race.
Motiviation:
We have a lot of duplicated code which makes it hard to maintain.
Modification:
Move shared code to UnsafeByteBufUtil and use it in the implementations.
Result:
Less duplicated code and so easier to maintain.
Motiviation:
We have a lot of duplicated code which makes it hard to maintain.
Modification:
Move shared code to HeapByteBufUtil and use it in the implementations.
Result:
Less duplicated code and so easier to maintain.
Motivation:
sun.misc.Unsafe allows us to handle heap ByteBuf in a more efficient matter. We should use special ByteBuf implementation when sun.misc.Unsafe can be used to increase performance.
Modifications:
- Add PooledUnsafeHeapByteBuf and UnpooledUnsafeHeapByteBuf that are used when sun.misc.Unsafe is ready to use.
- Add UnsafeHeapSwappedByteBuf
Result:
Better performance when using heap buffers and sun.misc.Unsafe is ready to use.
Motivation:
We had a bug in our implemention which double "reversed" bytes on systems which not support unaligned access.
Modifications:
- Correctly only reverse bytes if needed.
- Share code between unsafe implementations.
Result:
No more data-corruption on sytems without unaligned access.
Motivation:
When moving bytes between a PooledUnsafeDirectByteBuf or an UnpooledUnsafeDirectByteBuf
and a ByteBuffer, a temp ByteBuffer is allocated and will need to be GCed. This is a
common case since a ByteBuffer is always needed when reading/writing on a file,
for example.
Modifications:
Use PlatformDependent.copyMemory() to avoid the need for the temp ByteBuffer
Result:
No temp ByteBuffer allocated and GCed.
Motivation:
SlicedByteBuf did double reference count checking for various bulk operations, which affects performance.
Modifications:
- Add package private method to AbstractByteBuf that can be used to check indexes without check the reference count
- Use this new method in the bulk operation os SlicedByteBuf as the reference count checks take place on the wrapped buffer anyway
- Fix test-case to not try to read data that is out of the bounds of the buffer.
Result:
Better performance on bulk operations when using SlicedByteBuf (and sub-classes)
Motivation:
Some of the tests in the buffer module contained unused code. Some of the tests also used unnecessary inheritance which could be avoided to simplify code.
Modifications:
Cleanup the test cases.
Result:
Cleaner code, less cruft.
Motivation:
We need to always return a real slice even when the requested length is 0. This is needed as otherwise we not correctly share the reference count and so may leak a buffer if the user call release() on the returned slice and expect it to decrement the reference count of the "parent" buffer.
Modifications:
- Always return a real slice
- Add unit test for the bug.
Result:
No more leak possible when a user requests a slice of length 0 of a SlicedByteBuf.
Motivation:
SlicedByteBuf can be used for any ByteBuf implementations and so can not do any optimizations that could be done
when AbstractByteBuf is sliced.
Modifications:
- Add SlicedAbstractByteBuf that can eliminate range and reference count checks for _get* and _set* methods.
Result:
Faster SlicedByteBuf implementations for AbstractByteBuf sub-classes.
Motivation:
DuplicatedByteBuf can be used for any ByteBuf implementations and so can not do any optimizations that could be done
when AbstractByteBuf is duplicated.
Modifications:
- Add DuplicatedAbstractByteBuf that can eliminate range and reference count checks for _get* and _set* methods.
Result:
Faster DuplicatedByteBuf implementations for AbstractByteBuf sub-classes.
Motivation:
Calling AbstractByteBuf.toString(..., Charset) is used quite frequently by users but produce a lot of GC.
Modification:
- Use a FastThreadLocal to store the CharBuffer that are needed for decoding.
- Use internalNioBuffer(...) when possible
Result:
Less object creation / Less GC
Motiviation:
Checking reference count on every access on a ByteBuf can have some big performance overhead depending on how the access pattern is. If the user is sure that there are no reference count errors on his side it should be possible to disable the check and so gain the max performance.
Modification:
- Add io.netty.buffer.bytebuf.checkAccessible system property which allows to disable the checks. Enabled by default.
- Add microbenchmark
Result:
Increased performance for operations on the ByteBuf.
Motivation:
We should minimize and optimize bound checks as much as possible to get the most out of performance.
Modifications:
- Use bitwise operations to remove branching
- Remove branches when possible
Result:
Better performance for various operations.
Motivation:
ByteBufUtil.writeUtf8(...) / writeUsAscii(...) can use a fast-path when writing into AbstractByteBuf. We should try to unwrap WrappedByteBuf implementations so
we are able to do the same on wrapped AbstractByteBuf instances.
Modifications:
- Try to unwrap WrappedByteBuf to use the fast-path
Result:
Faster writing of utf8 and usascii for WrappedByteBuf instances.
Motivation:
As toString() is often used while logging we need to ensure this produces no exception.
Modifications:
Ensure we never throw an IllegalReferenceCountException.
Result:
Be able to log without produce exceptions.
Motivation:
The logic in ByteBufUtilTest.ByteBufUtilTest is wrong. It is attempting to ensure at least 1 byte is different in the ranges that will be subsequently compared, but does so before the copy operation.
Modifications:
- Move the code which ensures there is a difference to after the copy
- Simplify the logic which ensures there is a difference
Result:
Unit test now operates as designed.
Motivation:
ByteBufUtilTest.notEqualsBufferSubsections is testing non-equality but just uses random numbers to assume they will not be equal. Even after the random bytes are generated we should check they are infact not equal so the test has no chance of failing when it should not.
Modifications:
- Loop through bytes in notEqualsBufferSubsections after they are randomly generated to ensure there is atleast 1 difference.
Result:
More reliable unit tests.
Motivation:
We need to ensure all markers are reset when doing an allocation via the PooledByteBufAllocator. This was not the always the case.
Modifications:
Move all logic that needs to get executed when reuse a PooledByteBuf into one place and call it.
Result:
Correct behavior
Motivation:
When AsciiString is used we can optimize the write operation done by ByteBufUtil.writeUsAscii(...)
Modifications:
Sepcial handle AsciiString.
Result:
Faster writing of AsciiString.
Motivation:
The configurable property value recently added was not logged like others properties.
Modifications:
Added debug log with effective value applied.
Result:
Consistent with other properties
Motivation:
Leak detector, when it detects a leak, will print the last 5 stack
traces that touched the ByteBuf. In some cases that might not be enough
to identify the root cause of the leak.
Also, sometimes users might not be interested in tracing all the
operations on the buffer, but just the ones that are affecting the
reference count.
Modifications:
Added command line properties to override default values:
* Allow to configure max number of stack traces to collect
* Allow to only record retain/release operation on buffers
Result:
Users can increase the number of stack traces to debug buffer leaks
with lot of retain/release operations.
Motivation:
Currently the "derived" buffer will only ever be recycled if the release call is made on the "derived" object, and the "wrapped" buffer ends up being "fully released" (aka refcount goes to 0). From my experience this is not the common use case and thus the "derived" buffers will not be recycled.
Modifications:
- revert https://github.com/netty/netty/pull/3788
Result:
Less complexity, and less code to create new objects in majority of cases.
Motivation:
Even though MemoryRegionCache$Entry instances are allocated through a recycler they are not properly recycled,
leaving a lot of instances to be GCed along with Recycler$DefaultHandle objects.
Fixes#4071
Modification:
Recycle Entry when done using it.
Result:
Less GCed objects.
Motiviation:
The current read loops don't fascilitate reading a maximum amount of bytes. This capability is useful to have more fine grain control over how much data is injested.
Modifications:
- Add a setMaxBytesPerRead(int) and getMaxBytesPerRead() to ChannelConfig
- Add a setMaxBytesPerIndividualRead(int) and getMaxBytesPerIndividualRead to ChannelConfig
- Add methods to RecvByteBufAllocator so that a pluggable scheme can be used to control the behavior of the read loop.
- Modify read loop for all transport types to respect the new RecvByteBufAllocator API
Result:
The ability to control how many bytes are read for each read operation/loop, and a more extensible read loop.
Motivation:
As we modify the position of the passed in ByteBuffer's this methods are not thread-safe.
Modifications:
Duplicate the input ByteBuffers before copy the content to byte[].
Result:
Unpooled.copiedBuffer(ByteBuffer) and copiedBuffer(ByteBuffer...) is now thread-safe.
Motivation:
The javadoc of ByteBuf contained some out-dated code.
Modifications:
Update code example in javadoc to use netty 4+ API
Result:
Correct javadocs
Motivation:
FixedCompositeByteBuf does not properly implement a number of methods for
copying its content to direct buffers and output streams
Modifications:
Replace improper use of capacity() with readableBytes() when computing offesets during writes
Result:
Copying works correctly
Motivation:
At the moment we use 1 * cores as default mimimum for pool arenas. This can easily lead to conditions as we use 2 * cores as default for EventLoop's when using NIO or EPOLL. If we choose a smaller number we will run into hotspots as allocation and deallocation needs to be synchronized on the PoolArena.
Modifications:
Change the default number of arenas to 2 * cores.
Result:
Less conditions when using the default settings.
Motivation:
Dumping the content of a ByteBuf in a hex format is very useful.
Modifications:
Move code into ByteBufUtil so its easy to reuse.
Result:
Easy to reuse dumping code.
Motivation:
PoolThreadCache did only cache allocations if the allocation and deallocation Thread were the same. This is not optimal as often people write from differen thread then the actual EventLoop thread.
Modification:
- Add MpscArrayQueue which was forked from jctools and lightly modified.
- Use MpscArrayQueue for caches and always add buffer back to the cache that belongs to the allocation thread.
Result:
ThreadPoolCache is now also usable and so gives performance improvements when allocation and deallocation thread are different.
Performance when using same thread for allocation and deallocation is noticable worse then before.
Motivation:
Currently we hold a lock on the PoolArena when we allocate / free PoolSubpages, which is wasteful as this also affects "normal" allocations. The same is true vice-verse.
Modifications:
Ensure we synchronize on the head of the PoolSubPages pool. This is done per size and so it is possible to concurrently allocate / deallocate PoolSubPages with different sizes, and also normal allocations.
Result:
Less condition and so faster allocation/deallocation.
Before this commit:
xxx:~/wrk $ ./wrk -H 'Connection: keep-alive' -d 120 -c 256 -t 16 -s scripts/pipeline-many.lua http://xxx:8080/plaintext
Running 2m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 17.61ms 29.52ms 689.73ms 97.27%
Req/Sec 278.93k 41.97k 351.04k 84.83%
530527460 requests in 2.00m, 71.64GB read
Requests/sec: 4422226.13
Transfer/sec: 611.52MB
After this commit:
xxx:~/wrk $ ./wrk -H 'Connection: keep-alive' -d 120 -c 256 -t 16 -s scripts/pipeline-many.lua http://xxx:8080/plaintext
Running 2m test @ http://xxx:8080/plaintext
16 threads and 256 connections
Thread Stats Avg Stdev Max +/- Stdev
Latency 15.85ms 24.50ms 681.61ms 97.42%
Req/Sec 287.14k 38.39k 360.33k 85.88%
547902773 requests in 2.00m, 73.99GB read
Requests/sec: 4567066.11
Transfer/sec: 631.55MB
This is reproducable every time.
Motiviation:
At the moment we sometimes hold the lock on the PoolArena during destroy a PoolChunk. This is not needed.
Modification:
- Ensure we not hold the lock during destroy a PoolChunk
- Move all synchronized usage in PoolArena
- Cleanup
Result:
Less condition.
Motivation:
The PooledByteBufAllocator is more or less a black-box atm. We need to expose some metrics to allow the user to get a better idea how to tune it.
Modifications:
- Expose different metrics via PooledByteBufAllocator
- Add *Metrics interfaces
Result:
It is now easy to gather metrics and detail about the PooledByteBufAllocator and so get a better understanding about resource-usage etc.
Motivation:
At the moment when calling slice(...) or duplicate(...) on a Pooled*ByteBuf a new SlicedByteBuf or DuplicatedByteBuf. This can create a lot of GC.
Modifications:
Add PooledSlicedByteBuf and PooledDuplicatedByteBuf which will be used when a PooledByteBuf is used.
Result:
Less GC.
Motivation:
From the javadocs of ByteBuf.duplicate() it is not clear if the reader and writer marks will be duplicated.
Modifications:
Add sentence to clarify that marks will not be duplicated.
Result:
Clear semantics.
Motivation:
When allocate a PooledByteBuf we need to ensure to also reset the markers for the readerIndex and writerIndex.
Modifications:
- Correct reset the markers
- Add test-case for it
Result:
Correctly reset markers.
Motiviation:
When tried to allocate tiny and small sized and failed to serve these out of the PoolSubPage we exit the synchronization
block just to enter it again when call allocateNormal(...).
Modification:
Not exit the synchronized block until allocateNormal(...) is done.
Result:
Better performance.
