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https://issues.apache.org/jira/browse/CASSANDRA-9673?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14630677#comment-14630677
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Stefania commented on CASSANDRA-9673:
-------------------------------------
The user profile is correct, I verified with a temporary debug line that
SP.syncWriteToBatchlog() is executing.
With progressively bigger tests it gets clearer however that the GC times
improve with the patched version. I've attached the results with *n=500000*,
file 004, along with the JMC screenshots of the GC times of the first node.
> Improve batchlog write path
> ---------------------------
>
> Key: CASSANDRA-9673
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9673
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Aleksey Yeschenko
> Assignee: Stefania
> Fix For: 3.0.0 rc1
>
> Attachments: 9673_001.tar.gz, 9673_004.tar.gz,
> gc_times_first_node_patched_004.png, gc_times_first_node_trunk_004.png
>
>
> Currently we allocate an on-heap {{ByteBuffer}} to serialize the batched
> mutations into, before sending it to a distant node, generating unnecessary
> garbage (potentially a lot of it).
> With materialized views using the batchlog, it would be nice to optimise the
> write path:
> - introduce a new verb ({{Batch}})
> - introduce a new message ({{BatchMessage}}) that would encapsulate the
> mutations, expiration, and creation time (similar to {{HintMessage}} in
> CASSANDRA-6230)
> - have MS serialize it directly instead of relying on an intermediate buffer
> To avoid merely shifting the temp buffer to the receiving side(s) we should
> change the structure of the batchlog table to use a list or a map of
> individual mutations.
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