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https://issues.apache.org/jira/browse/CASSANDRA-8496?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Benedict updated CASSANDRA-8496:
--------------------------------
Description:
To improve clearing of the CL, prevent infinite growth, and ensure the prompt
completion of tasks waiting on flush in the case of transient errors, large
flushes or slow disks, in 2.1 we could eliminate the post flusher altogether.
Since we now enforce that Memtables track contiguous ranges, a relatively small
change would permit Memtables to know the exact minimum as well as the
currently known exact maximum. The CL could easily track the total dirty range,
knowing that it must be contiguous, by using an AtomicLong instead of an
AtomicInteger, and tracking both the min/max seen, not just the max. The only
slight complexity will come in for tracking the _clean_ range as this can now
be non-contiguous, if there are 3 memtable flushes covering the same CL
segment, and one of them completes later. To solve this we can use an interval
tree since these operations are infrequent, so the extra overhead is nominal.
Once the interval tree completely overlaps the dirty range, we mark the entire
dirty range clean.
was:
To improve clearing of the CL and the prompt completion of tasks waiting on
flush in the case of transient errors, large flushes or slow disks, in 2.1 we
could eliminate the post flusher altogether.
Since we now enforce that Memtables track contiguous ranges, a relatively small
change would permit Memtables to know the exact minimum as well as the
currently known exact maximum. The CL could easily track the total dirty range,
knowing that it must be contiguous, by using an AtomicLong instead of an
AtomicInteger, and tracking both the min/max seen, not just the max. The only
slight complexity will come in for tracking the _clean_ range as this can now
be non-contiguous, if there are 3 memtable flushes covering the same CL
segment, and one of them completes later. To solve this we can use an interval
tree since these operations are infrequent, so the extra overhead is nominal.
Once the interval tree completely overlaps the dirty range, we mark the entire
dirty range clean.
> Remove MemtablePostFlusher
> --------------------------
>
> Key: CASSANDRA-8496
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8496
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Benedict
> Priority: Minor
>
> To improve clearing of the CL, prevent infinite growth, and ensure the prompt
> completion of tasks waiting on flush in the case of transient errors, large
> flushes or slow disks, in 2.1 we could eliminate the post flusher altogether.
> Since we now enforce that Memtables track contiguous ranges, a relatively
> small change would permit Memtables to know the exact minimum as well as the
> currently known exact maximum. The CL could easily track the total dirty
> range, knowing that it must be contiguous, by using an AtomicLong instead of
> an AtomicInteger, and tracking both the min/max seen, not just the max. The
> only slight complexity will come in for tracking the _clean_ range as this
> can now be non-contiguous, if there are 3 memtable flushes covering the same
> CL segment, and one of them completes later. To solve this we can use an
> interval tree since these operations are infrequent, so the extra overhead is
> nominal. Once the interval tree completely overlaps the dirty range, we mark
> the entire dirty range clean.
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