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Posted to issues@kudu.apache.org by "Todd Lipcon (JIRA)" <ji...@apache.org> on 2016/12/11 16:17:58 UTC

[jira] [Created] (KUDU-1801) High lock contention on TableInfo objects

Todd Lipcon created KUDU-1801:
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             Summary: High lock contention on TableInfo objects
                 Key: KUDU-1801
                 URL: https://issues.apache.org/jira/browse/KUDU-1801
             Project: Kudu
          Issue Type: Bug
          Components: master
            Reporter: Todd Lipcon
            Assignee: Todd Lipcon


In an Impala test on a 200-node cluster with 40 concurrent query streams, I see the master has high contention on TableInfo::lock_. Two issues seem to be at play:
1) we could easily swap it for a rwlock for a big win, since it's a read-mostly structure
2) GetTableSchema() calls IsCreateTableDone() which is O(n) in the number of tablets. For each tablet, we acquire its rwc lock, so the iteration isn't cheap. The table-wide "create table done" state seems quite cacheable.



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