ASG
IBM
Zystems
Cressida
Icon
Netflexity
 
  MQSeries.net
Search  Search       Tech Exchange      Education      Certifications      Library      Info Center      SupportPacs      LinkedIn  Search  Search                                                                   FAQ  FAQ   Usergroups  Usergroups
 
Register  ::  Log in Log in to check your private messages
 
RSS Feed - WebSphere MQ Support RSS Feed - Message Broker Support

MQSeries.net Forum Index » Multiphase Commit » Duplicate XID - How long MQ holds on to an XID

Post new topic  Reply to topic
 Duplicate XID - How long MQ holds on to an XID « View previous topic :: View next topic » 
Author Message
IntegratorWMB
PostPosted: Mon Jan 04, 2010 8:36 am    Post subject: Duplicate XID - How long MQ holds on to an XID Reply with quote

Apprentice

Joined: 06 Dec 2007
Posts: 27

I am using a 3rd Party Transaction Manager. Currently this software, creates an unique XID. The software do not generate the same XID and during shutdown it writes in to a file and reads it upon restart.

Deleting this file, results in Duplicate XID for websphere MQ. My question is how does MQ knows the XID is a duplicate one even after the transaction is committed/rolledback.

I assume it holds on to all XID's for a specific period of time. Is my assumption correct?

If so, is there an easy way to set that time period (or) flush all existing XID's from mq server.

Note : I dont have any issues in our production environment.(where the server access is controlled).

I face this issue in my development environment where the head count of developers are high, and deletion of this file results in the problem of duplicate xid. Also, if we use the same XID after a period of time ( say anything above x days (or) so, I dont see the problem). Sometime the x is 5 (or) 6 (or) 7 day(s) and above and its not consistent. Any suggestions?

Thanks for any inputs.
Back to top
View user's profile Send private message
bruce2359
PostPosted: Mon Jan 04, 2010 8:48 am    Post subject: Reply with quote

Poobah

Joined: 05 Jan 2008
Posts: 9394
Location: US: west coast, almost. Otherwise, enroute.

Quote:
Deleting this file, results in Duplicate XID for websphere MQ.

Why would you delete a critical component of WMQ or your 3rd party transaction manager?! What outcome would you expect - other than the one you got?

Quote:
My question is how does MQ knows the XID is a duplicate one even after the transaction is committed/rolledback.

The xid (logical unit of work id) represents messages that are/were part of a UofW that WMQ may need to replay at some point during a backout or restart. Starting a new UofW with a pre-existing id violates the XA protocol. This is working as designed.
_________________
I like deadlines. I like to wave as they pass by.
ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live.
Back to top
View user's profile Send private message
mvic
PostPosted: Mon Jan 04, 2010 8:56 am    Post subject: Re: Duplicate XID - How long MQ holds on to an XID Reply with quote

Jedi

Joined: 09 Mar 2004
Posts: 2080

IntegratorWMB wrote:
Deleting this file, results in Duplicate XID for websphere MQ. My question is how does MQ knows the XID is a duplicate one even after the transaction is committed/rolledback.

A qmgr keeps a list of all transactions it needs to know about. If it still knows about one, it must still be in the list so the TM must not yet have told the qmgr it is committed or rolled back.

Quote:
I assume it holds on to all XID's for a specific period of time. Is my assumption correct?

No, the qmgr maintains its knowledge of the transaction as long as this is needed under the XA specification. This could be forever, if your qmgr sits unused forever.

If you restart your qmgr, all transactions that are not committed or prepared (ie. have completed 1st phase of the 2 phase commit) are rolled back.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic  Reply to topic Page 1 of 1

MQSeries.net Forum Index » Multiphase Commit » Duplicate XID - How long MQ holds on to an XID
Jump to:  



You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
Protected by Anti-Spam ACP
 
 


Theme by Dustin Baccetti
Powered by phpBB © 2001, 2002 phpBB Group

Copyright © MQSeries.net. All rights reserved.