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https://issues.apache.org/jira/browse/CASSANDRA-20074?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17897995#comment-17897995
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Stefan Miklosovic commented on CASSANDRA-20074:
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[CASSANDRA-20074-4.1|https://github.com/instaclustr/cassandra/tree/CASSANDRA-20074-4.1]
{noformat}
java11_pre-commit_tests
✓ j11_build 1m 39s
✓ j11_cqlsh_dtests_py3 5m 37s
✓ j11_cqlsh_dtests_py311 5m 47s
✓ j11_cqlsh_dtests_py311_vnode 5m 56s
✓ j11_cqlsh_dtests_py38 5m 25s
✓ j11_cqlsh_dtests_py38_vnode 7m 19s
✓ j11_cqlsh_dtests_py3_vnode 5m 55s
✓ j11_cqlshlib_cython_tests 7m 10s
✓ j11_cqlshlib_tests 6m 23s
✓ j11_dtests 33m 49s
✓ j11_dtests_vnode 36m 20s
✓ j11_jvm_dtests 16m 23s
✓ j11_jvm_dtests_vnode 16m 17s
✓ j11_unit_tests 10m 4s
{noformat}
[java11_pre-commit_tests|https://app.circleci.com/pipelines/github/instaclustr/cassandra/4990/workflows/969b704f-daad-4e93-8a0c-88f8a2d6c27d]
> AbstractCommitLogService#lastSyncedAt initialized with currentTimeMillis()
> but later compared and updated with System.nanoTime()
> ---------------------------------------------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-20074
> URL: https://issues.apache.org/jira/browse/CASSANDRA-20074
> Project: Cassandra
> Issue Type: Bug
> Components: Local/Commit Log
> Reporter: Dmitry Konstantinov
> Assignee: Dmitry Konstantinov
> Priority: Low
> Fix For: 4.0.x, 4.1.x, 5.0.x, 5.x
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Within org.apache.cassandra.db.commitlog.AbstractCommitLogService
> we use System.currentMillis()-based time to initialize lastSyncedAt field:
> {code:java}
> protected volatile long lastSyncedAt = currentTimeMillis();{code}
> but later we use clock.now() = System.nanoTime() to compare and update the
> field value:
> {code:java}
> long pollStarted = clock.now();
> boolean flushToDisk = lastSyncedAt + syncIntervalNanos <= pollStarted ||
> state != NORMAL || syncRequested; {code}
> As of now we are lucky that in the current JDK implementations
> System.nanoTime() is much bigger than currentTimeMillis() but it is not
> guaranteed by a specification of the API. If nanoTime() <
> currentTimeMillis() then we can stuck without sync of commit log to disk.
> So, we need to align the time sources and change the init logic to:
> {code:java}
> protected volatile long lastSyncedAt = preciseTime.now();{code}
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