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https://issues.apache.org/jira/browse/DIRMINA-1103?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16810567#comment-16810567
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Jörg Michelberger commented on DIRMINA-1103:
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Thats right, but current code is always recreate the inBytes and outBytes
byte[] for usage with zStream API and they are then copied to/from IoBuffer to
communicate with MINA API.
The point is that the IoBuffers are not referenced in a CG-Root way in Zlib,
but the inBytes and outBytes are, which leads to a replacement on the next
deflate/inflate call. This is the earliest point in time where these byte[]s
are GC-able. In the current flow they are GC-ed anyway, but unfortunatelly at
the next call, where all the zStream in and out are always replaced by the new
buffers and sizes.
My change wants to make them GC-able in the current inflate/deflate call. Which
is IMHO a non critical and non "behavior" changing thing, leading only to
earlier buffer releasing. I have that patch running in my environment which
causes to no disturbing behaviour and the byte[]s "die young".
Reusing is a different story and not in the scope of the change.
> Avoid sticky byte array buffers in Zlib CompressionFilter
> ---------------------------------------------------------
>
> Key: DIRMINA-1103
> URL: https://issues.apache.org/jira/browse/DIRMINA-1103
> Project: MINA
> Issue Type: Improvement
> Affects Versions: 2.0.21
> Reporter: Jörg Michelberger
> Priority: Major
>
> For each Zlib instance there is a zStream instance which is equipped with new
> buffers for each in and out of inflate / deflate. This buffers are not
> released after each inflate / deflate. So the last compressed and
> uncompressed byte[] and its content for rx and tx is not garbage collectable
> on each session.
> It would be great if there was a reset(zStream) method on Zlib which sets the
> in and out to static empty byte[] to release these buffers after usage quite
> before returning from Zlib.deflate and Zlib.inflate but in the synchronized
> block. Something like:
> {{private void resetZStream (zStream) {}}
> {{ zStream.next_in = EMPTY_BYTE_ARRAY;}}
> {{ zStream.next_in_index = 0;}}
> {{ zStream.avail_in = 0;}}
> {{ zStream.next_out = EMPTY_BYTE_ARRAY;}}
> {{ zStream.next_out_index = 0;}}
> {{ zStream.avail_out = 0;}}
> {{}}}
>
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