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  1. MariaDB Server
  2. MDEV-4956

Reduce usage of LOCK_open: TABLE_SHARE::tdc.used_tables

        Details

        • Type: Task
        • Status: Closed
        • Priority: Major
        • Resolution: Fixed
        • Fix Version/s: 10.0.7
        • Component/s: None
        • Labels:
          None

          Description

          tc_acquire_table and tc_release_table are critical sections of table cache. Among other things, they update TABLE_SHARE::tdc.used_tables:
          tc_acquire_table - push new TABLE object to used_tables
          tc_release_table - remove TABLE object from used_tables

          used_tables list is not really necessary for table cache to operate properly. We can change it with all_tables list instead. tc_acquire_table and tc_release_table wont need to access all_tables list at all.

          The cost is as following:

          • 2 additional pointers per TABLE object
          • SHOW OPEN TABLES will have to iterate all_tables and skip objects with in_use == 0
          • same for TABLE_SHARE::visit_subgraph()
          • same for kill_delayed_threads_for_table()

          A patch for this task has been tested (read-only single table OLTP, 4 CPU linux server) and shown ~30% lower LOCK_open wait time and ~20% higher tps.

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                relates to

                Bug - A problem which impairs or prevents the functions of the product. MDEV-5864 Reduce usage of LOCK_open: TABLE_SHARE::tdc.free_tables

                • Major - Major loss of function.
                • Closed

                Task - A task that needs to be done. MDEV-5388 Reduce usage of LOCK_open: unused_tables

                • Major - Major loss of function.
                • Closed

                Task - A task that needs to be done. MDEV-5492 Reduce usage of LOCK_open: TABLE::in_use

                • Major - Major loss of function.
                • Closed

                Task - A task that needs to be done. MDEV-4702 Reduce usage of LOCK_open

                • Major - Major loss of function.
                • Closed

                Task - A task that needs to be done. MDEV-5403 Reduce usage of LOCK_open: tc_count

                • Major - Major loss of function.
                • Closed

                Task - A task that needs to be done. MDEV-5597 Reduce usage of LOCK_open: LOCK_flush

                • Major - Major loss of function.
                • Closed

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                  svoj Sergey Vojtovich added a comment -

                  Sergei, please review attached patch. Committed patch didn't reach mailing list for some reason.

                  Show
                  svoj Sergey Vojtovich added a comment - Sergei, please review attached patch. Committed patch didn't reach mailing list for some reason.
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                  svoj Sergey Vojtovich added a comment -

                  Sergei, please review updated patch:
                  Date: Tue, 10 Dec 2013 15:00:43 +0000 (UTC)
                  From: Sergey Vojtovich <svoj@mariadb.org>
                  To: commits@mariadb.org
                  Subject: [Commits] Rev 3914: MDEV-4956 - Reduce usage of LOCK_open: TABLE_SHARE::tdc.used_tables in lp:maria/10.0

                  Show
                  svoj Sergey Vojtovich added a comment - Sergei, please review updated patch: Date: Tue, 10 Dec 2013 15:00:43 +0000 (UTC) From: Sergey Vojtovich <svoj@mariadb.org> To: commits@mariadb.org Subject: [Commits] Rev 3914: MDEV-4956 - Reduce usage of LOCK_open: TABLE_SHARE::tdc.used_tables in lp:maria/10.0
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                  svoj Sergey Vojtovich added a comment -

                  Pushed to 10.0.7, revision-id: svoj@mariadb.org-20131210150036-imkvngj5125mukqu

                  Show
                  svoj Sergey Vojtovich added a comment - Pushed to 10.0.7, revision-id: svoj@mariadb.org-20131210150036-imkvngj5125mukqu

                    People

                    • Assignee:
                      serg Sergei Golubchik
                      Reporter:
                      svoj Sergey Vojtovich
                    • Votes:
                      0 Vote for this issue
                      Watchers:
                      4 Start watching this issue

                      Dates

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                        Updated:
                        Resolved:

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