ASF GitHub Bot commented on NIFI-4794:

Github user asfgit closed the pull request at:


> Improve Garbage Collection required by Provenance Repository
> ------------------------------------------------------------
>                 Key: NIFI-4794
>                 URL: https://issues.apache.org/jira/browse/NIFI-4794
>             Project: Apache NiFi
>          Issue Type: Improvement
>          Components: Core Framework
>            Reporter: Mark Payne
>            Assignee: Mark Payne
>            Priority: Major
>             Fix For: 1.6.0
> The EventIdFirstSchemaRecordWriter that is used by the provenance repository 
> has a writeRecord(ProvenanceEventRecord) method. Within this method, it 
> serializes the given record into a byte array by serializing to a 
> ByteArrayOutputStream (after wrapping the BAOS in a DataOutputStream). Once 
> this is done, it calls toByteArray() on that BAOS so that it can write the 
> byte[] directly to another OutputStream.
> This can create a rather large amount of garbage to be collected. We can 
> improve this significantly:
>  # Instead of creating a new ByteArrayOutputStream each time, create a pool 
> of them. This avoids constantly having to garbage collect them.
>  # If said BAOS grows beyond a certain size, we should not return it to the 
> pool because we don't want to keep a huge impact on the heap.
>  # Instead of wrapping the BAOS in a new DataOutputStream, the 
> DataOutputStream should be pooled/recycled as well. Since it must create an 
> internal byte[] for the writeUTF method, this can save a significant amount 
> of garbage.
>  # Avoid calling ByteArrayOutputStream.toByteArray(). We can instead just use 
> ByteArrayOutputStream.writeTo(OutputStream). This avoids both allocating that 
> new array/copying the data, and the GC overhead.

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