1 Reply Latest reply: Mar 25, 2011 4:34 PM by 850503 RSS

    MMON Deadlock

    850503
      Hi All,

      Strange situation today at the office.

      My system:
      Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
      PL/SQL Release 11.1.0.6.0 - Production
      "CORE     11.1.0.6.0     Production"
      TNS for IBM/AIX RISC System/6000: Version 11.1.0.6.0 - Production
      NLSRTL Version 11.1.0.6.0 - Production

      select * from dba_outstanding_alerts;
      Metrics "Database Time Spent Waiting (%)" is at 100 for event class "Concurrency"
      Metrics "Database Time Spent Waiting (%)" is at 100 for event class "Other"
      Session 551 is blocking 2 other sessions
      Session 501 is blocking 2 other sessions

      Session 501 is from program M001 so seems to be MMON

      MMON => Managebility Monitor is the enabling process for many of the self-monitoring and self-tuning capabilities,
      MMON captures statistics which are used by ADDM.

      Having select * from dba_advisor_tasks it seems i am missing snapshots for the last 3 days.

      My assumption is that this situation is a deadlock of MMON,
      i resolved the issue by startup force, but when we have moved to production I don't want to be doing startup force.

      How would I resolve this issue since I am not able to kill system sessions, and without resolving this deadlock some processes can't be run,
      but I don't want to do startup force.....

      Any reflections on this?

      Thanks!
        • 1. Re: MMON Deadlock
          850503
          From my private test system I killed the MMON process and it restarted,
          so it seems an option to kill the MMON process using kill -9.

          But I am unsure if this is the preferred option.

          Any reflections.