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Problem IT35039
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Status: Closed |
EXCEPTION CAUGHT DURING QUERY OF SYSSCBLST TABLE MAY LEAVE MUTEXLOCKED WITH POTENTIAL FOR DEADLOCK
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| product: |
INFORMIX SERVER / 5725A3900 / C10 - IDS 12.10 |
| Problem description: |
The processing of a query for the pseudo table sysscblst in the
sysmaster database may result in an exception which interrupts
the query processing. The clean up of the query processing may
leave a mutex named scbthd in a locked state which can later
lead to a deadlock situation. The deadlock can be seen in the
output of the "onstat -g wmx" command as in this example:
Mutexes with waiters:
mid addr name holder lkcnt
waiter waittime
19 443a3838 session 19099537 0 20
1729
19099536 1729
718290922 21044fca0 scbthd 19099536 0
19094197 1729
19099537 1729
The thread with id 19099537 is the holder of the session mutex
and is waiting for access to the scbthd mutex. The thread
holding that mutex, with id 19099536, is waiting for the session
mutex and the result is deadlock. A typical stack for the thread
holding the session mutex may be:
yield_processor_mvp
mt_lock_wait
mt_lock_helper
mt_prscblst
pstread
pst_rsread
rsread
fmread
readseq_single
gettupl
scan_next
hjoin_next
hjoin_next
sort_open
prepselect
open_cursor
sql_open
sq_open
sqmain
An example stack for the thread holding the scbthd mutex may be:
yield_processor_mvp
mt_lock_wait
mt_lock_helper
destroy_session
sq_exit
sqmain
Other stacks for this thread may be possible.
Queries using the sysmaster view syssessions are also
susceptible. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* Users of Informix Server prior to 12.10.xC15 and 14.10.xC6. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Informix Server 12.10.xC15 (when available) or *
* 14.10.xC6 (when available). *
**************************************************************** |
| Local Fix: |
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| Solution |
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| Workaround |
****************************************************************
* USERS AFFECTED: *
* Users of Informix Server prior to 12.10.xC15 and 14.10.xC6. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Informix Server 12.10.xC15 (when available) or *
* 14.10.xC6 (when available). *
**************************************************************** |
| Comment |
Fixed in Informix Server 12.10.xC15 and 14.10.xC6. |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 24.11.2020
10.12.2020
10.12.2020 |
| Problem solved at the following versions (IBM BugInfos) |
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| Problem solved according to the fixlist(s) of the following version(s) |
