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  1. MariaDB Server
  2. MDEV-27850

MTR tests can hang due to DEBUG_SYNC race condition

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    Details

    • Type: Bug
    • Status: In Progress (View Workflow)
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9
    • Fix Version/s: 10.3
    • Component/s: Replication, Tests
    • Labels:
      None

      Description

      If a DEBUG_SYNC signal is overwritten before the target thread acknowledges the signal, the thread will become stuck (until timeout) due to awaiting the missed signal. rpl.rpl_seconds_behind_master_spike highlights this problem with an example fix commit cdf19cd.

      Other tests which may be impacted by this issue are rpl.rpl_dump_request_retry_warning, main.query_cache_debug, and main.partition_debug_sync. A comprehensive list of effected tests should be created, and then they should be fixed.

      Edit:
      The following is an (ongoing) list of tests which are potentially impacted by this race condition along with a message if fixed. Note that part of this work extended the debug_sync mechanism to automatically detect when an unacknowledged signal is overwritten or reset, and this list contains all tests which fail from that detection:

      • innodb.innodb-table-online
      • innodb.innodb-index-online
      • binlog_encryption.rpl_parallel
      • binlog_encryption.rpl_parallel_ignored_errors
      • rpl.rpl_get_master_version_and_clock
      • rpl.rpl_parallel
      • rpl.rpl_parallel_ignored_errors
      • rpl.kill_race_condition
      • rpl.rpl_seconds_behind_master_spike (fixed)
      • rpl.rpl_dump_request_retry_warning (fixed)
      • main.query_cache_debug (fixed)
      • main.partition_debug_sync (fixed)

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            Assignee:
            bnestere Brandon Nesterenko
            Reporter:
            bnestere Brandon Nesterenko
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              Dates

              Created:
              Updated:

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