"Pmon Failed To Acquire Latch" Messages in Alert Log -Database Hung

(Doc ID 468740.1)

Last updated on NOVEMBER 28, 2016

Applies to:

Oracle Database - Enterprise Edition - Version 10.2.0.1 to 11.1.0.7 [Release 10.2 to 11.1]
Information in this document applies to any platform.
***Checked for relevance on 15-Apr-2016***

Symptoms

Database Instance hangs and connections to database using 'sqlplus' are also not possible.

Checking te alert.log, following messages are seen:

PMON failed to acquire latch, see PMON dump
Fri Oct 5 10:33:00 2007
PMON failed to acquire latch, see PMON dump
Fri Oct 5 10:34:05 2007
PMON failed to acquire latch, see PMON dump
Errors in file /dwrac/BDUMP/dwhp_pmon_1912834.trc:


This will also dump a systemstate dump and the location will be mentioned in alert.log

Also at OS level, we see that MMAN is consuming lot of CPU.

On checking the system state dump, we see that MMAN is holding the Shared pool Latch and Location of Latch is kgh_next_free or quiesce extents

SO: 3df6835b8, type: 2, owner: 0, flag: INIT/-/-/0x00
(process) Oracle pid=4, calls cur/top: 3dfa94c48/3dfa94c48, flag: (6)
SYSTEM
int error: 0, call error: 0, sess error: 0, txn error 0
(post info) last post received: 0 0 24
(latch info) wait_event=0 bits=80
holding (efd=3) 3800db408 Child shared pool level=7 child#=1
Location from where latch is held: kgh_next_free:
Context saved from call: 0
state=busy, wlstate=free
waiter count=3
Process Group: DEFAULT, pseudo proc: 3df77a4b8
O/S info: user: oracle10, term: UNKNOWN, ospid: 25931
OSD pid info: Unix process pid: 25931, image: oracle@dbname (MMAN)


Short call stack would be like

... kghquiesce_regular_extent kgh_next_free ksmc_next_free kmgs_extract_mem_from_granule @kmgs_check_inuse_lists ...

 

Cause

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