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U0777 abend in IMS transaction

 
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cdhami

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Joined: 24 Jan 2006
Posts: 28

PostPosted: Tue Jul 21, 2009 5:56 pm    Post subject: U0777 abend in IMS transaction
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Hi ppl.
Pls help me with the error U0777 in IMS transactions.
the log shows that both resources in deadlock are same transaction.
pls help me to understand the reason. is there some specific definition required for ims transaction such that deadlock doesn't occur. or something else is required ....

pls find log below
[size=7][size=9]DEADLOCK ANALYSIS REPORT - LOCK MANAGER IS IRLM
...............................................................................
RESOURCE DMB-NAME LOCK-LEN LOCK-NAME - WAITER FOR THIS RESOURCE IS VICTIM
01 OF 02 DF11E002 08 0001FC3085CB02C6
KEY FOR RESOURCE IS NOT AVAILABLE
IMS-NAME TRAN/JOB PSB-NAME PCB--DBD PST# RGN CALL LOCK LOCKFUNC STATE
WAITER PROD BB100T13 BB100 DBF11 00045 MPP GET GFPLL 904004F0 08
BLCKER IMP7 BB100T13 BB100 -------- 00031 MPP ---- ----- -------- 08
...............................................................................
RESOURCE DMB-NAME LOCK-LEN LOCK-NAME
02 OF 02 D800E004 08 002655C0828404C6
KEY FOR RESOURCE IS NOT AVAILABLE
IMS-NAME TRAN/JOB PSB-NAME PCB--DBD PST# RGN CALL LOCK LOCKFUNC STATE
WAITER IMP7 BB100T13 BB100 DB800 00031 MPP GET GFPLL 904004F0 08
BLCKER PROD BB100T13 BB100 -------- 00045 MPP ---- ----- -------- 08
[/size][/size]
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enrico-sorichetti

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Location: italy

PostPosted: Tue Jul 21, 2009 8:52 pm    Post subject: Reply to: U0777 abend in IMS transaction
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Quote:
is there some specific definition required for ims transaction such that deadlock doesn't occur. or something else is required ....


simply better programming ( maybe with a revision of requirements )
when two transactions access at the same time the same 2 resources in reverse order then a deadlock will always occur

tran 1 accessing resource A wil enq

tran 2 accessing resource B will enq

now when tran 1 will try to access resource B will go into a wait state
the same will happen to tran 2 accessing rsource A,
hence the deadlock

review,review,review your application
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cdhami

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Joined: 24 Jan 2006
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PostPosted: Wed Jul 22, 2009 11:30 am    Post subject:
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Hi Enrico,
Thanks for the info,

but the issue here is my transaction is not expected to be running twice at same time..???
thats why, i am sensing that there is problem with transaction definition..!!

Let me know, if you have more information on such a situation.

Thanks and Regards
Chandrajeet
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dick scherrer

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Joined: 23 Nov 2006
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Location: Inside the Matrix

PostPosted: Wed Jul 22, 2009 9:31 pm    Post subject:
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Hello,

Quote:
but the issue here is my transaction is not expected to be running twice at same time..???
This is not caused by one transaction. This is caused by 2 different transactions trying to lock the same resource in reverse order (as Enrico explained).
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cdhami

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PostPosted: Thu Jul 23, 2009 10:56 am    Post subject:
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Hi Dick,
I am able to see waiter and blocker as same transaction involved in deadlock...!!! from the IMS logs

Rgds
Chandra
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dick scherrer

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PostPosted: Thu Jul 23, 2009 7:31 pm    Post subject:
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Hello,

Suggest you look at the code an determine why the locks are not issued in the same sequence.

If the code operated consistently, the deadlock would not occur.

The "second" execution would simply wait for the lock to be freed.
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