[jira] [Comment Edited] (CASSANDRA-12269) Faster write path

["T Jake Luciani (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-12269?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15388437#comment-15388437 ] 

T Jake Luciani edited comment on CASSANDRA-12269 at 7/21/16 9:14 PM:
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[branch|https://github.com/tjake/cassandra/tree/write-perf]
[testall|http://cassci.datastax.com/job/tjake-write-perf-testall]
[dtests|http://cassci.datastax.com/job/tjake-write-perf-dtest/]

I wasn't able to close the gap on throughput but it's improved and latency now matches 2.2, see [cstar comparison|http://cstar.datastax.com/graph?command=one_job&stats=fea54640-4ebc-11e6-a5e8-0256e416528f]  

CommitLogStress is also improved by ~15%



was (Author: tjake):

[branch|https://github.com/tjake/cassandra/tree/write-perf][testall|http://cassci.datastax.com/job/tjake-write-perf-testall][dtests|http://cassci.datastax.com/job/tjake-write-perf-dtest/]

I wasn't able to close the gap on throughput but it's improved and latency now matches 2.2, see [cstar comparison|http://cstar.datastax.com/graph?command=one_job&stats=fea54640-4ebc-11e6-a5e8-0256e416528f]  

CommitLogStress is also improved by ~15%


> Faster write path
> -----------------
>
>                 Key: CASSANDRA-12269
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12269
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: T Jake Luciani
>            Assignee: T Jake Luciani
>             Fix For: 3.10
>
>
> The new storage engine (CASSANDRA-8099) has caused a regression in write performance.  This ticket is to address these to try and bring 3.0 as close to 2.2 as possible. There are four main reasons for this I've discovered after much toil:
> 1.  The cost of calculating the size of a serialized row is higher now since we no longer have the cell name and value managed as ByteBuffers as we did pre-3.0.  That means we current re-serialize the row twice, once to calculate the size and once to write the data.  This happens during the SSTable writes and was addressed in CASSANDRA-9766.
>      Double serialization is also happening in CommitLog and the MessagingService.  We need to apply the same techniques to these as we did to the SSTable serialization.
> 2.  Even after fixing (1) there is still an issue with there being more GC pressure and CPU usage in 3.0 due to the fact that we encode everything from the {{Column}} to the {{Row}} to the {{Partition}} as a {{BTree}}.  Specifically, the {{BTreeSearchIterator}} is used for all iterator() methods.  Both these classes are useful for efficient removal and searching of the trees but in the case of SerDe we almost always want to simply walk the entire tree forwards or reversed and apply a function to each element.  To that end, we can use lambdas and do this without any extra classes.
> 3.  We use a lot of thread locals and check them constantly on the read/write paths.  For client warnings, tracing, temp buffers, etc.  We should move all thread locals to FastThreadLocals and threads to FastThreadLocalThreads.
> 4.  We changed the memtable flusher defaults in 3.2 that caused a regression see: CASSANDRA-12228



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