Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-22278

change temp-pool to be 0 by default

    XMLWordPrintable

    Details

    • Type: Task
    • Status: Closed (View Workflow)
    • Priority: Critical
    • Resolution: Fixed
    • Fix Version/s: 10.5.7
    • Component/s: Server
    • Labels:
      None

      Description

      change temp-pool to be 0 by default and deprecate it

      According to benchmarks made by Axel (and further analysis) , this code behind --temp-pool=1 in create_tmp_table() causes a heavy mutex contention:

      if (use_temp_pool && !(test_flags & TEST_KEEP_TMP_TABLES))

      temp_pool_slot = bitmap_lock_set_next(&temp_pool);

      The --temp-pool option was implemented to address some bottleneck in Linux kernel, which is reported to be fixed nowadays.

      In MySQL, --temp-pool was deprecated in 5.7 and removed in 8.0.

      Let's do the following:

      • Set --temp-pool=0 by default in MariaDB-10.5 (currently its default is 1)
      • Mark it as deprecated in mysqld --help output
      • Remove it in some later version, tentatively in 10.6.

      In the meanwhile, we should try to find proves that this problem was really addressed in Linux.

        Attachments

          Issue Links

            Activity

              People

              Assignee:
              bar Alexander Barkov
              Reporter:
              serg Sergei Golubchik
              Votes:
              1 Vote for this issue
              Watchers:
              3 Start watching this issue

                Dates

                Created:
                Updated:
                Resolved: