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From "Peter Schuller (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-4032) memtable.updateLiveRatio() is blocking, causing insane latencies for writes
Date Fri, 09 Mar 2012 18:06:58 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-4032?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Peter Schuller updated CASSANDRA-4032:
--------------------------------------

    Attachment: CASSANDRA-4032-1.1.0-v2.txt

Attaching {{v2}}. Keeps NBHM mapping CFS -> AtomicBoolean. Mappings are never removed (assuming
reasonably bound number of unique CFS:s during a lifetime). Queue used for DTPE is unbounded.

                
> memtable.updateLiveRatio() is blocking, causing insane latencies for writes
> ---------------------------------------------------------------------------
>
>                 Key: CASSANDRA-4032
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4032
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Peter Schuller
>            Assignee: Peter Schuller
>             Fix For: 1.1.0
>
>         Attachments: CASSANDRA-4032-1.1.0-v1.txt, CASSANDRA-4032-1.1.0-v2.txt
>
>
> Reproduce by just starting a fresh cassandra with a heap large enough for live ratio
calculation (which is {{O(n)}}) to be insanely slow, and then running {{./bin/stress -d host
-n100000000 -t10}}. With a large enough heap and default flushing behavior this is bad enough
that stress gets timeouts.
> Example ("blocked for" is my debug log added around submit()):
> {code}
>  INFO [MemoryMeter:1] 2012-03-09 15:07:30,857 Memtable.java (line 198) CFS(Keyspace='Keyspace1',
ColumnFamily='Standard1') liveRatio is 8.89014894083727 (just-counted was 8.89014894083727).
 calculation took 28273ms for 1320245 columns
>  WARN [MutationStage:8] 2012-03-09 15:07:30,857 Memtable.java (line 209) submit() blocked
for: 231135
> {code}
> The calling code was written assuming a RejectedExecutionException is thrown, but it's
not because {{DebuggableThreadPoolExecutor}} installs a blocking rejection handler.

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