PMON failed to acquire latch, see PMON dump

PMON failed to acquire latch, see PMON dump

PMON failed to acquire latch, see PMON dump

 

 

    今天在关闭数据库的时候，shutdown immediate之后系统就hang住了，其他进程也连不上库。查看了alert.log日志，发现大量出现“PMON failed to acquire latch, see PMON dump”这个错误，到网上查了一下，据说是个bug，在一篇博文上找到了解决的办法：

 

http://blog.chinaunix.net/u/6436/showart_1918697.html

 

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To implement the solution, execute the following steps:

1. In $ORACLE_HOME/network/admin/listener.ora, of the database where the Metadata Repository is to be loaded, add the line:
INBOUND_CONNECT_TIMEOUT_LISTENER = 0

2. In the Oracle Server 10g sqlnet.ora, add the line:
SQLNET.INBOUND_CONNECT_TIMEOUT = 0

3. Stop and restart the database and the listener for the changes to take effect

 

这是metalink上的：

 

Applies to:
Oracle Server - Enterprise Edition - Version: 10.2.0.1.0 to 10.2.0.3.0

 

This problem can occur on any platform.

 

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

Checking alert.log we see following messages

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.

Cause

Currently this issue is being worked upon by development in

 

 

Bug 6488694
- DATABSE HUNG WITH PMON FAILED TO ACQUIRE LATCH MESSAGE

 

 

Solution
As of now only workaround is to disable Automatic Shared Memory Management (

 

ASMM
) i.e Setting

 

SGA_TARGET=0

Also as per bug, you can can set following event and restart the instance

EVENT="10235 trace name context forever, level 2"

 

Development is suspecting memory corruption in this case. So with the above event, database might hit ORA-600 before spin. The trace file of ORA-600 would help investigate the issue. These trace files need to be sent to Oracle support for investigation.

Note : - Event 10235 with level 2 or higher can impact latch contention.Though may not be quite critical. In case you see latch contention then unset the event

References
Bug 6488694
- DATABSE HUNG WITH PMON FAILED TO ACQUIRE LATCH MESSAGE

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    最后没办法，hang住之后系统sys用户都登不进，无法使用任何操作，只能重启机器之后数据库恢复正常。希望加了那两个参数之后不要再发生这样的Bug，虽然对数据库的危害不大，但是需要重启机器还是比较严重的。