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https://issues.apache.org/jira/browse/CASSANDRA-9673?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14711322#comment-14711322
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T Jake Luciani edited comment on CASSANDRA-9673 at 8/25/15 2:10 PM:
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bq. However it doesn't go through SP.mutateMV() so I don't see how we could
have broken it, perhaps because we've removed the dedicated stage?
You removed the dedicated stage? Yes that would cause these timeouts. If you
have 32 mutation slots and you are doing 32 MV updates at once that leaves no
MUTATION slots for batchlog updates (these happen inside executing mutation)
was (Author: tjake):
bq. However it doesn't go through SP.mutateMV() so I don't see how we could
have broken it, perhaps because we've removed the dedicated stage?
You removed the dedicated stage? Yes that would cause these timeouts.
> 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
> Labels: performance
> Fix For: 3.0 beta 2
>
> 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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