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https://issues.apache.org/jira/browse/CASSANDRA-19477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17829791#comment-17829791
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Stefan Miklosovic commented on CASSANDRA-19477:
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[CASSANDRA-19477-4.1|https://github.com/instaclustr/cassandra/tree/CASSANDRA-19477-4.1]
{noformat}
java11_pre-commit_tests
✓ j11_build 1m 30s
✓ j11_cqlsh_dtests_py3 5m 28s
✓ j11_cqlsh_dtests_py311 5m 47s
✓ j11_cqlsh_dtests_py311_vnode 6m 4s
✓ j11_cqlsh_dtests_py38 5m 53s
✓ j11_cqlsh_dtests_py38_vnode 6m 2s
✓ j11_cqlsh_dtests_py3_vnode 5m 53s
✓ j11_cqlshlib_cython_tests 9m 1s
✓ j11_cqlshlib_tests 8m 6s
✓ j11_dtests 33m 38s
✓ j11_dtests_vnode 36m 1s
✓ j11_jvm_dtests 15m 44s
✓ j11_jvm_dtests_repeat 38m 12s
✓ j11_jvm_dtests_vnode 12m 39s
✓ j11_jvm_dtests_vnode_repeat 38m 46s
✓ j11_unit_tests_repeat 0m 32s
✕ j11_unit_tests 8m 33s
org.apache.cassandra.cql3.MemtableSizeTest testSize[skiplist]
{noformat}
[java11_pre-commit_tests|https://app.circleci.com/pipelines/github/instaclustr/cassandra/4064/workflows/88c6d9da-308c-43a7-849b-a2b1a6b30307]
> Do not go to disk to get HintsStore.getTotalFileSize
> ----------------------------------------------------
>
> Key: CASSANDRA-19477
> URL: https://issues.apache.org/jira/browse/CASSANDRA-19477
> Project: Cassandra
> Issue Type: Bug
> Components: Consistency/Hints
> Reporter: Jon Haddad
> Assignee: Stefan Miklosovic
> Priority: Normal
> Fix For: 4.1.x, 5.0-rc, 5.x
>
> Attachments: flamegraph.cpu.html
>
> Time Spent: 4h 10m
> Remaining Estimate: 0h
>
> When testing a cluster with more requests than it could handle, I noticed
> significant CPU time (25%) spent in HintsStore.getTotalFileSize. Here's what
> I'm seeing from profiling:
> 10% of CPU time spent in HintsDescriptor.fileName which only does this:
>
> {noformat}
> return String.format("%s-%s-%s.hints", hostId, timestamp, version);{noformat}
> At a bare minimum here we should create this string up front with the host
> and version and eliminate 2 of the 3 substitutions, but I think it's probably
> faster to use a StringBuilder and avoid the underlying regular expression
> altogether.
> 12% of the time is spent in org.apache.cassandra.io.util.File.length. It
> looks like this is called once for each hint file on disk for each host we're
> hinting to. In the case of an overloaded cluster, this is significant. It
> would be better if we were to track the file size in memory for each hint
> file and reference that rather than go to the filesystem.
> These fairly small changes should make Cassandra more reliable when under
> load spikes.
> CPU Flame graph attached.
> I only tested this in 4.1 but it looks like this is present up to trunk.
>
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