[jira] [Commented] (DIRMINA-1103) Avoid sticky byte array buffers in Zlib CompressionFilter

["Emmanuel Lecharny (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DIRMINA-1103?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16809906#comment-16809906 ] 

Emmanuel Lecharny commented on DIRMINA-1103:
--------------------------------------------

As Jonathan said on the mailing list, resetting the {{zlib}} buffers after each call would be done a the cost of creating them back when handling a new message.Now, there are various scenarii:
 * each session is only used once. That's ok, when the session is 'killed', the {{zlib}} instance get garbled
 * each session can send many messages. You may want to reuse the {{zlib}} instance with its existing buffers, instead of creating them again and again for each compressed/decompressed messages
 * you have many, many sessions, with only a few of them active at a given time. In this case, not holding the{{ }}{{zlib}} buffers forever makes sense, they are only useful for the sessions being processed. Otherwise, you may have a problem with all the pending buffers which are not used but eating the memory

I guess you are trying to get the third scenario implemented, right ?

> 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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