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https://issues.apache.org/jira/browse/CASSANDRA-3578?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13815618#comment-13815618
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Vijay commented on CASSANDRA-3578:
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Hi Benedict, archiver.maybeArchive(segment.getPath(), segment.getName()) is a
blocking call and will need to be a separate thread it might involve user
defined archival.
{quote}
sync() would mark things as flushed to disk that weren't, which would result in
log messages never being persisted
{quote}
My understand is that.... Calling force will sync the dirty pages and if we do
a concurrent writes to the same page they will be marked as dirty and will be
synched in the next call, how will we loose the log messages?
I still like the original approach :) of creating files (it may be just me)
because of simplicity and we can be aggressive in allocator threads similar to
your patch (to create empty files and deleting them).
> Multithreaded commitlog
> -----------------------
>
> Key: CASSANDRA-3578
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3578
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Jonathan Ellis
> Assignee: Vijay
> Priority: Minor
> Labels: performance
> Attachments: 0001-CASSANDRA-3578.patch, ComitlogStress.java,
> Current-CL.png, Multi-Threded-CL.png, parallel_commit_log_2.patch
>
>
> Brian Aker pointed out a while ago that allowing multiple threads to modify
> the commitlog simultaneously (reserving space for each with a CAS first, the
> way we do in the SlabAllocator.Region.allocate) can improve performance,
> since you're not bottlenecking on a single thread to do all the copying and
> CRC computation.
> Now that we use mmap'd CommitLog segments (CASSANDRA-3411) this becomes
> doable.
> (moved from CASSANDRA-622, which was getting a bit muddled.)
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