Instance Hangs or Crashes as LMS Waits for latch 'gc element' Held by DIAG Process

(Doc ID 1348264.1)

Last updated on MARCH 21, 2018

Applies to:

Oracle Server - Enterprise Edition - Version: 11.2.0.1 and later   [Release: 11.2 and later ]
Information in this document applies to any platform.

Symptoms

If DIAG process holds latch "gc element" and dumps system state, if can block LMS from getting the latch and cause instance to hang or crash:

  • Instance alert.log
LMS1 (ospid: 31959) waits for latch 'gc element' for 49 secs.
..
ORA-29771: process DIAG (OSID 31937) blocks LMS1 (OSID 31959) for more than 70 seconds
..
DIAG (ospid: 31937) is hanging without a blocker.
LMHB (ospid: 31965) kills DIAG (ospid: 31937).
..
 
OR


LMS0 (ospid: 25991) waits for latch 'gc element' for 8 secs.
..
ORA-29770: global enqueue process LMS0 (OSID 25991) is hung for more than 140 seconds
..
LMHB (ospid: 26001): terminating the instance due to error 29770
..
opiodr aborting process unknown ospid (26195) as a result of ORA-1092

  • Short stack dump
diag process:

..__sighandler write sdbgrfwf_write_file .. kcldle kclbsy ksudss ksdxfdmp

OR

..__sighandler _IO_vfprintf vsprintf     .. kcldle kclbsy ksudss ksdxfdmp



lms process:

..skgpwwait kslgess ksl_get_shared_latch kclpdc kclfpbl kclfbst kcl_fairness kclgeneratecr..

  • hanganalyze wait cycle
    Oracle session identified by:
    {
                instance: 1 (otms11.otms11a)
                   os id: 31745
              process id: 14, oracle@embahl205 (LMS1)
              session id: 911
        session serial #: 1
    }
    is waiting for 'latch: gc element' with wait info:
    {
..
            time in wait: 1.126043 sec
      heur. time in wait: 42.069154 sec <<<<<<<<<<<
..

    }
    and is blocked by
 => Oracle session identified by:
    {
                instance: 1 (otms11.otms11a)
                   os id: 31711
              process id: 6, oracle@embahl205 (DIAG)
              session id: 391
        session serial #: 1
    }
    which is not in a wait


Cause

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