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| Failed to attach shared memory segment |
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| jimmycallaghan11 |
 Posted: Wed Mar 12, 2008 9:33 am Post subject: Failed to attach shared memory segment |
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Newbie
Joined: 12 Mar 2008
Posts: 3
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Hi all,
We're running JBoss and MQ on our Debian server and recently we've started to see this error:
Probe Type :- MSGAMQ6119
Probe Severity :- 2
Probe Description :- AMQ6119: An internal WebSphere MQ error has occurred (Failed to attach shared memory segment: shmat(ShmId 0x00040008) [rc=-1 errno=12] Cannot allocate memory)
Now I would have thought that JBoss and MQ would keep themselves to themselves and that one should not influence the other. However, when I restart my JBoss server the problem disappears for about 20 hours but then the errors start coming in again. My thought is that as JBoss is running, it slowly uses more and more shared memory until MQ can no longer get what it needs.
I suppose my questions are:
1. Does my theory about JBoss sound OK? Can shared memory be consumed in this way?
2. How can I find out what is using the shared memory that MQ is trying to get?
We've doubled the maximum shared memory segment size but it's had little effect. Nothing has changed much on the server over the last 2 years but this started happening last week.
Any pointers in the right direction would be appreciated. |
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| jefflowrey |
| Posted: Wed Mar 12, 2008 9:36 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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Likely, you've deployed an app into JBOSS that has a bindings connection handle leak.
_________________
I am *not* the model of the modern major general. |
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| jimmycallaghan11 |
| Posted: Wed Mar 12, 2008 10:13 am Post subject: |
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Newbie
Joined: 12 Mar 2008
Posts: 3
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Thanks for the incredibly swift reply!
However, at the risk of sounding dumb, what do you mean by a "bindings connection handle leak"? If I do a:
ps aux | grep amqzlaa0
I can see that there are only 9 connections and this number never really changes. When we got the problem I look at top and can see that there's not a lot of memory spare. However, it seems that JBoss isn't using more than its 2Mb that I've given it (and we've got 4Mb available). I will put a memory monitor on JBoss and see what trend we get overnight. |
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| jimmycallaghan11 |
| Posted: Thu Mar 13, 2008 1:52 am Post subject: Shared Memory |
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Newbie
Joined: 12 Mar 2008
Posts: 3
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We are running a failover hardware architecture for this application. Basically we have two servers with identical applications on them (MQ and JBOSS). When requests are not answered by the primary server, the secondary answers them. Our shared memory is occurring on the secondary server at the moment and comparing the memory between the two shows some interesting differences.
Running ipcs -m on the primary gives:
| Code: |
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x85803fad 0 mqm 666 1000 28
0x05803ff0 98307 mqm 666 8790016 25
0x05804000 163845 mqm 666 18178048 24
0x05804003 262152 mqm 644 8790016 1
0x0580400f 589842 mqm 666 131072 17
0x05804010 622611 mqm 666 1159168 2
0x05804011 655380 mqm 666 327680 5
0x05804129 786456 mqm 666 8192 1
0x0580412a 819225 mqm 666 8192 1 |
on the secondary
| Code: |
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x85887346 0 mqm 666 1000 30
0x0588738b 98307 mqm 666 8790016 27
0x0588739b 163845 mqm 666 12713984 26
0x0588739e 262152 mqm 644 8790016 1
0x058873aa 589842 mqm 666 131072 19
0x058873ab 622611 mqm 666 1159168 2
0x058873ac 655380 mqm 666 327680 5
0x0588747d 786456 mqm 666 8192 1
0x0588748f 819225 mqm 666 8192 1
0x058874b2 983070 mqm 666 3637248 24
0x05887521 1245222 mqm 666 7270400 23
0x05887524 1343529 mqm 666 14536704 23
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As you can see, mqm is using significantly more shared memory on the secondary server than it is on the primary. I would normally put this down to load but the primary gets FAR more load than the secondary. |
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