Uploaded image for project: 'Core Server'
  1. Core Server
  2. SERVER-48399

Writing config document to "local.system.replset" should not acquire database lock in stronger mode (X).

    XMLWordPrintableJSON

Details

    • Icon: Improvement Improvement
    • Resolution: Duplicate
    • Icon: Major - P3 Major - P3
    • None
    • None
    • Replication
    • Replication
    • 5

    Description

      It seems when the node persists new config in collection "local.system.replset", it takes "local" database lock in stronger mode (X) and PBWM lock in IS mode. This can lead to 2 major side effects.
      1) Since PBWM lock is taken in IS mode, this can block the secondary oplog applier which requires PBWM in X mode. This can result in replication lag. This will be addressed by SERVER-48398
      2) Since it takes "local" database lock in X mode, this can block other local database readers and writers.

      • Mainly, if this node X is the sync source for node Y, then the oplog fetcher of the node Y can be blocked behind the the reconfig via heartbeat thread due to database lock conflict, leading to replication lag.

      Attachments

        Activity

          People

            backlog-server-repl Backlog - Replication Team
            suganthi.mani@mongodb.com Suganthi Mani
            Votes:
            0 Vote for this issue
            Watchers:
            10 Start watching this issue

            Dates

              Created:
              Updated:
              Resolved: