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https://issues.apache.org/jira/browse/ASTERIXDB-1147?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Young-Seok Kim updated ASTERIXDB-1147:
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Assignee: Till Westmann
> ConcurrentLockManager's performance bug when there are many locks on a single
> resource, such as dataset level lock
> ------------------------------------------------------------------------------------------------------------------
>
> Key: ASTERIXDB-1147
> URL: https://issues.apache.org/jira/browse/ASTERIXDB-1147
> Project: Apache AsterixDB
> Issue Type: Bug
> Reporter: Young-Seok Kim
> Assignee: Till Westmann
>
> If a query scan a dataset which includes 1M records, the scan operator
> acquires 1M instantTryLocks.
> Internally, ConcurrentLockManager holds 1M tryLocks in dataset level and 1M
> instantTryLocks in entity level. In other words, 1M dataset level locks are
> not released until the job is over.
> If this situation happens, ConcurrentLockManager allocates 1M
> lockRequestSlots during lock acquiring phase and those slots are maintained
> in a linked list. Thus, when the job is over, those slots for the dataset
> level locks are released one at a time by searching each slot for each
> dataset level lock held by scanning the linked list. Thus, 1M slots of linked
> list is scanned 1M times. This is killing the scan performance.
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