[jira] [Commented] (NIFI-3648) Address Excessive Garbage Collection

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/NIFI-3648?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15949243#comment-15949243 ] 

ASF GitHub Bot commented on NIFI-3648:
--------------------------------------

GitHub user mosermw opened a pull request:

    https://github.com/apache/nifi/pull/1637

    NIFI-3648 removed cluster message copying when not in debug mode

    I expect NIFI-3648 could have several PRs, and that they will not be included in 1.2.0 release, so review of this can be delayed until the rest of that ticket is PRed and reviewed.  I just wanted to get this in so I don't forget.
    
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You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/mosermw/nifi nifi-3648-1

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/nifi/pull/1637.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #1637
    
----
commit 55d93ccbec8fd7eaede0759e7abb550c75d36a63
Author: Mike Moser <mo...@apache.org>
Date:   2017-03-30T14:34:26Z

    NIFI-3648 removed message copying when not in debug mode

----


> Address Excessive Garbage Collection
> ------------------------------------
>
>                 Key: NIFI-3648
>                 URL: https://issues.apache.org/jira/browse/NIFI-3648
>             Project: Apache NiFi
>          Issue Type: Improvement
>          Components: Core Framework, Extensions
>            Reporter: Mark Payne
>            Assignee: Mark Payne
>
> We have a lot of places in the codebase where we generate lots of unnecessary garbage - especially byte arrays. We need to clean this up to in order to relieve stress on the garbage collector.
> Specific points that I've found create unnecessary garbage:
> Provenance CompressableRecordWriter creates a new BufferedOutputStream for each 'compression block' that it creates. Each one has a 64 KB byte[]. This is very wasteful. We should instead subclass BufferedOutputStream so that we are able to provide a byte[] to use instead of an int that indicates the size. This way, we can just keep re-using the same byte[] that we create for each writer. This saves about 32,000 of these 64 KB byte[] for each writer that we create. And we create more than 1 of these per minute.
> EvaluateJsonPath uses a BufferedInputStream but it is not necessary, because the underlying library will also buffer data. So we are unnecessarily creating a lot of byte[]'s
> CompressContent uses Buffered Input AND Output. And uses 64 KB byte[]. And doesn't need them at all, because it reads and writes with its own byte[] buffer via StreamUtils.copy
> Site-to-site uses CompressionInputStream. This stream creates a new byte[] in the readChunkHeader() method continually. We should instead only create a new byte[] if we need a bigger buffer and otherwise just use an offset & length variable.
> Right now, SplitText uses TextLineDemarcator. The fill() method increases the size of the internal byte[] by 8 KB each time. When dealing with a large chunk of data, this is VERY expensive on GC because we continually create a byte[] and then discard it to create a new one. Take for example an 800 KB chunk. We would do this 100,000 times. If we instead double the size we would only have to create 8 of these.
> Other Processors that use Buffered streams unnecessarily:
> ConvertJSONToSQL
> ExecuteProcess
> ExecuteStreamCommand
> AttributesToJSON
> EvaluateJsonPath (when writing to content)
> ExtractGrok
> JmsConsumer



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