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  1. MariaDB Server
  2. MDEV-5403

Reduce usage of LOCK_open: tc_count

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    Details

    • Type: Task
    • Status: Closed (View Workflow)
    • Priority: Major
    • Resolution: Fixed
    • Fix Version/s: 10.0.9
    • Component/s: None
    • Labels:
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      Description

      tc_release_table is critical section of table cache. Among other things, it checks if table cache threshold is reached and if so evicts to-be-released table. This is done by comparing tc_count with tc_size.

      tc_count can be atomic and checked beyond of LOCK_open. Besides it is last global variable protected by this lock.

      The cost is as following:

      • tc_add_table() assumed that there is nothing to evict if tc_count > tc_size and skipped expensive LRU lookup. This assumption will be broken and LRU lookup must be done if tc_count >= tc_size.

      A patch for this task hasn't been benchmarked yet.

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              Assignee:
              svoj Sergey Vojtovich
              Reporter:
              svoj Sergey Vojtovich
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                Updated:
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