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https://issues.apache.org/jira/browse/CASSANDRA-14261?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16377368#comment-16377368
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Jeff Jirsa commented on CASSANDRA-14261:
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I don't, because I did them on a laptop on a plane over the holidays, and it's
decidedly synthetic non-prod tests, but these looked simple and sufficiently
isolated not to warrant a full run in perf.
Here's an estimate from memory though:
[this|https://github.com/jeffjirsa/cassandra/commit/b2b2d765c089c5be609d65f04611b2800ffa70b8]
was based on seeing that function in the stack about 5% of the time in
compaction, and it goes from 5% to ~0.001% with that trivial patch.
[this|https://github.com/jeffjirsa/cassandra/commit/dc8070eaa5ec52e8be46358777fe42d9944f5f30]
was based on seeing ~130MB of allocations (about 3.12% of the TLAB allocation
for a 9 second span).
And
[this|https://github.com/jeffjirsa/cassandra/commit/391846e4d0cfd8c8076c3e6050fb0b13496e24ed]
I expect to never show up in profiles except under very high contention, which
I have little desire to manually test, but it should be fairly obvious to most
people that it's both safe and necessary.
> Compaction Profiling Improvements
> ---------------------------------
>
> Key: CASSANDRA-14261
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14261
> Project: Cassandra
> Issue Type: Improvement
> Components: Compaction
> Reporter: Jeff Jirsa
> Assignee: Jeff Jirsa
> Priority: Minor
> Fix For: 4.x
>
>
> There's some low hanging fruit in some laptop compaction runs, such as
> creating a ton of the same object unnecessarily and hashing cell names
> repeatedly to see if a column is dropped even when we should know that the
> table has no dropped columns.
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