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gpklos
PostPosted: Fri Jan 09, 2004 11:48 am    Post subject: Broken Client Connections Reply with quote

Centurion

Joined: 24 May 2002
Posts: 108

I'm curious - what exactly happens if we are connected to a qmgr via a client, doing MQGETs. Now what happens if the connection is broken due to a tcpip error? Obviously the client is no longer there. I assume the queue manager backs anything out that was committed. But actually I was more concerned about cleanup. Does the queue manager immediately close the queue? Or is the queue left open until the heartbeat interval is executed. So if there was a very large heartbeat interval, then would the queue "technically" remain open till the queue manager executes the heartbeat and notices the connection is no longer there?
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EddieA
PostPosted: Fri Jan 09, 2004 1:37 pm    Post subject: Reply with quote

Jedi

Joined: 28 Jun 2001
Posts: 2453
Location: Los Angeles

Quote:
I assume the queue manager backs anything out that was committed

NO. If it's committed, then it's commited. The Queue Manager will only back out something that is still within a UOW that HASN'T been committed. That's why you have to think a little more about UOWs and Synpoint when using Client connections.

Not sure about when MQ realises that the application has been 'cut off at the knees', but why does it matter.

Cheers,
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JasonE
PostPosted: Fri Jan 09, 2004 1:44 pm    Post subject: Reply with quote

Grand Master

Joined: 03 Nov 2003
Posts: 1220
Location: Hursley

The server closes the connection when and if it finds out about the client going away. TCPIP socket breaks generally only are identified at data send time, therefore:

If the client is not in an API call, then the server is in a receive. It will ONLY disconnect when keepalive pops (by default 2 hours on most o/s's without any configuration change). If keep alive isnt enabled, chances are it wont be closed.

If the client is inside an API call when it dies (powers off etc) then at some point the server will try to send the result back, and it is this time the break is detected.

If the api call is a get/wait but client heartbeats are enabled, then periodic sends are attempted to confirm the client is still there waiting for the response.
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gpklos
PostPosted: Mon Jan 12, 2004 4:22 am    Post subject: Broken Client Connections Reply with quote

Centurion

Joined: 24 May 2002
Posts: 108

I'm sorry about the question. I meant to say I assume the qmgr backs out anything that wasn't committed.
Sorry to mislead you guys. However your replies were still helpful.

Thanks,
Gary
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