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  1. Core Server
  2. SERVER-38341

Remove Parallel Batch Writer Mutex

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Details

    • Storage Execution
    • Fully Compatible
    • Execution NAMR Team 2023-08-21

    Description

      Currently here is my understanding of the PBWM:

      • Primaries take it in IS for all reads and writes. This is unnecessary because it will never conflict with anything
      • Secondaries take it in X around a batch
      • Secondary oplog appliers don't take it at all
      • Snapshot secondary readers never take it
      • Secondary readers only take it in IS if there is no lastApplied to read from

      The lock is only really used to serialize the second and fifth bullets above. It should be fairly straightforward to always have a lastApplied value to read from on secondaries. This extra lock adds a lot of code complexity with very little value and is high value code cleanup.

      Attachments

        Issue Links

          depends on

          Task - A task that needs to be done. SERVER-79391 Stop taking PBWM with global lock

          • Major - P3 - Major loss of function.
          • Closed

          Task - A task that needs to be done. SERVER-79392 Remove ParallelBatchWriterMode class

          • Major - P3 - Major loss of function.
          • Closed

          Task - A task that needs to be done. SERVER-79398 Remove PBWM support from sleep command

          • Major - P3 - Major loss of function.
          • Closed

          Task - A task that needs to be done. SERVER-79399 Remove ShouldNotConflictWithSecondaryBatchApplicationBlock and related functions

          • Major - P3 - Major loss of function.
          • Closed

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-47866 Secondary readers do not need to reacquire PBWM lock if there are catalog conflicts

          • Major - P3 - Major loss of function.
          • Closed

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-50970 Support secondary reads in ephemeralForTest

          • Major - P3 - Major loss of function.
          • Closed
          is depended on by

          Bug - A problem which impairs or prevents the functions of the product. SERVER-41010 getMinValid() in bgsync shouldn't conflict with PBWM lock

          • Major - P3 - Major loss of function.
          • Backlog

          Task - A task that needs to be done. SERVER-79804 Clean up references to PBWM in our architecture guide

          • Major - P3 - Major loss of function.
          • Closed
          is related to

          Bug - A problem which impairs or prevents the functions of the product. SERVER-44105 Perform ShardServerCatalogLoader writes in a single transaction

          • Major - P3 - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. SERVER-48518 Rollback via refetch (EMRC = false) can make readers to see the rolled back data even after the rollback node catches up to primary.

          • Major - P3 - Major loss of function.
          • Closed

          Task - A task that needs to be done. SERVER-78599 Prevent change collections from truncating inconsistent data

          • Major - P3 - Major loss of function.
          • Closed

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-48398 Writing config document to "local.system.replset" should not acquire PBWM lock.

          • Major - P3 - Major loss of function.
          • Backlog

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-26006 Audit all background tasks and decide which should conflict with replication application

          • Major - P3 - Major loss of function.
          • Closed

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-48399 Writing config document to "local.system.replset" should not acquire database lock in stronger mode (X).

          • Major - P3 - Major loss of function.
          • Closed
          related to

          Bug - A problem which impairs or prevents the functions of the product. SERVER-44821 retrieving storage stats for currentOp blocked by slow oplog application

          • Major - P3 - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. SERVER-44859 plan_cache_index_create.js is blocked on two phase index build commit

          • Major - P3 - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. SERVER-44943 avoid taking the PBWM lock in ReplicationCoordinatorExternalStateImpl::oplogExists()

          • Major - P3 - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. SERVER-44944 avoid taking the PBWM lock in SessionsCollectionRS::_isStandaloneOrPrimary()

          • Major - P3 - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. SERVER-45007 PBWM acquisition in GlobalLock constructor ignores deadline

          • Major - P3 - Major loss of function.
          • Closed

          Task - A task that needs to be done. SERVER-41407 Create a test suite that does secondary reads and also kills secondaries

          • Major - P3 - Major loss of function.
          • Backlog

          Activity

            People

              gregory.noma@mongodb.com Gregory Noma
              judah.schvimer@mongodb.com Judah Schvimer
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              Dates

                Created:
                Updated:
                Resolved: