IDS Forum

Locked Mutex session - freezing instance

Posted By: Cesar Inacio Martins
Date: Thursday, 3 February 2011, at 11:15 a.m.

Hi

AIX 5
IFX 10 FC4

We had a situation here where the instance froze in a way which commands ONMODE no longer worked and freeze the open connection of new sessions.
Any ONMODE command executed, just freeze.

After found the suspect session what freeze everybody , we just could not killed it because the onmode don't worked too.
The solution was restart the server.

My question is, situations like these, is there other way to force kill the session?

The suspect session was appear be from our sentinel , where at this moment have a sqltrace active over a session. This session (sentinel) just keeped with running+reading state .
The lock occur over the mutex "session" . For what is used this mutex?

Moslty of the user access to the database is with IPCSHM and only few users with SOCTCP. But almost of users was locked on this mutex, just a couple of users keep running.

Here is some output saved :

> head -n 20 onstat.gwmx.out

IBM Informix Dynamic Server Version 10.00.FC4 -- On-Line -- Up 6 days 01:03:28 -- 7663184 Kbytes

Mutexes with waiters:
mid addr name holder lkcnt waiter waittime
12 70000000009c030 session 2494402 0 2516947 1639

2506557 1637

16 1636

2495653 1635

2516831 1635

20 1635

2516844 1635

2516915 1633

18 1633

14 1630

2516958 1622

2516830 1615

2516866 1605

2490871 1603

2514053 1599

>grep 2494402 onstat.ath.out
2494402 7000001afde96c8 7000001bc336d68 2 running 5cpu sqlexec

>grep 7000001bc336d68 onstat.u.out

7000001bc336d68 ---PR-- 262700 informix - 0 0 1 10 0

>cat onstat.gsql.out

IBM Informix Dynamic Server Version 10.00.FC4 -- On-Line -- Up 6 days 01:17:58 -- 7663184 Kbytes

Sess SQL Current Iso Lock SQL ISAM F.E.
Id Stmt type Database Lvl Mode ERR ERR Vers Explain
262700 SELECT sysmaster CR Not Wait 0 0 9.03 Off

Current statement name : _ifxc00000000003fx

Current SQL statement :
select t2.cbl_sessionid session_id, cbl_stmt[1,691] prpstm, t2.cbl_estcost

sqs_estcst, t2.cbl_estrows sqs_estrws, t2.cbl_seqscan sqs_seqscn,

t2.cbl_autoindex sqs_autoidx, t2.cbl_tempfile sqs_tempfls, cbl_sdbno

seqnum from sysmaster:'informix'.sysconblock t2 where

cbl_ismainblock='Y' AND length(cbl_stmt) between 190 AND 691 and

t2.cbl_sessionid in (244926)

Messages In This Thread

• Locked Mutex session - freezing instance
  Cesar Inacio Martins -- Thursday, 3 February 2011, at 11:15 a.m.
  • Re: Locked Mutex session - freezing instance
    Fernando Nunes -- Thursday, 3 February 2011, at 11:31 a.m.
  • Re: Locked Mutex session - freezing instance
    Art Kagel -- Thursday, 3 February 2011, at 12:03 p.m.
    • Re: Locked Mutex session - freezing instance
      Cesar Inacio Martins -- Friday, 4 February 2011, at 5:34 a.m.

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