4.1.0.Final

On Tue, Jul 19, 2016 at 2:48 PM, 'Norman Maurer' via Netty discussions <
[email protected]> wrote:

> Are you using 4.0 or 4.1 ?
>
> On 19 Jul 2016, at 20:42, Chris Conroy <[email protected]> wrote:
>
> I have not been able to reproduce locally yet, but I do see it in a
> cluster that takes a lot of varied traffic. The leak detector has not fired
> for this under advanced. I will give paranoid a shot to be safe, but it's
> my understanding that the leak detection framework is more for dealing with
> pooled byte buf misuse, but in this case I am exclusively using unpooled
> heap byte bufs: these are just the socket direct byte bufs that appear to
> be leaking.
>
> I meant to add this earlier: The path to GC root goes:
>
> io.netty.buffer.ByteBufUtil$ThreadLocalUnsafeDirectByteBuf
>   io.netty.util.Recycler$DefaultHandle
>     io.netty.util.Recycler$DefaultHandle[]
>       io.netty.util.Recycler#Stack
>         java.lang.Object[]
>           io.netty.util.internal.InternalThreadLocalMap
>             ... (more thread local map refs up to java.lang.Thread)
>
>
>
> On Tuesday, July 19, 2016 at 2:17:25 PM UTC-4, Norman Maurer wrote:
>>
>> Can you provide a reproducer? Also did you try to run with paranoid leak
>> detection
>>
>> Am 19.07.2016 um 20:04 schrieb Chris Conroy <[email protected]>:
>>
>> Ah okay: I didn't see the calls to failFlushed since they occur above the
>> stanza I found suspicious.
>>
>> So, the above explanation is probably not correct. Still, I am seeing a
>> leak where DirectByteBufs are rooted to the recycler, and the speed at
>> which these buffers leak appears to be correlated with slow/partial readers.
>>
>> On Monday, July 18, 2016 at 4:36:31 PM UTC-4, Norman Maurer wrote:
>>>
>>> failFlushed(...) should be called to fail and release all flushed
>>> messages.
>>>
>>> Are you saying this not happens?
>>>
>>> Am 18.07.2016 um 22:02 schrieb Chris Conroy <[email protected]>:
>>>
>>> I’ve been trying to track down a NIO memory leak that occurs in a Netty
>>> application I am porting from Netty 3 to Netty 4. This leak does not occur
>>> in the Netty 3 version of the application.
>>>
>>> For now, I’m using only unpooled heap buffers in Netty 4, but NIO
>>> buffers do come into play for socket communication.
>>>
>>> I’ve captured a few heap dumps from affected instances, and in each it
>>> appears that the leaked DirectByteBuf java objects are rooted in an
>>> io.netty.util.Recycler.
>>>
>>> These buffers remain indefinitely: I can disable the application to
>>> drain traffic and force GCs, but the # of NIO buffers and NIO allocated
>>> space stays flat.
>>>
>>> The issue is likely related to slow readers. However, the leak persists
>>> long after all channels have been closed.
>>>
>>> I implemented a writability listener and the leak does appear to go away
>>> if I stop writing to a channel after it goes unwritable. This is good, but
>>> I’m still worried that this just makes the problem less likely since it’s
>>> still possible to write/flush and have pending data: writability just
>>> limits how much data will be buffered.
>>>
>>> Digging into ChannelOutBoundBuffer I see the following stanza in close:
>>>
>>>
>>> // Release all unflushed messages.
>>> try {
>>>     Entry e = unflushedEntry;
>>>     while (e != null) {
>>>         // Just decrease; do not trigger any events via 
>>> decrementPendingOutboundBytes()
>>>         int size = e.pendingSize;
>>>         TOTAL_PENDING_SIZE_UPDATER.addAndGet(this, -size);
>>>
>>>         if (!e.cancelled) {
>>>             ReferenceCountUtil.safeRelease(e.msg);
>>>             safeFail(e.promise, cause);
>>>         }
>>>         e = e.recycleAndGetNext();
>>>     }
>>> } finally {
>>>     inFail = false;
>>> }
>>> clearNioBuffers();
>>>
>>> This seems a bit curious to me: why are flushed buffers not released
>>> here? Since the leak seems to be rooted in the Recycler, this could be the
>>> culprit…What do you think?
>>> ​
>>>
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