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Problem IT34183
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Status: Closed |
POOR PERFORMANCE OF QUERIES ON SYSSCBLST PSEUDO-TABLE MAY CAUSE OTHER THREADS TO WAIT ON SESSION MUTEX
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| product: |
INFORMIX SERVER / 5725A3900 / C10 - IDS 12.10 |
| Problem description: |
Informix instances with several thousand connected sessions may
experience poor performance of queries using the sysscblst
pseudo-table or syssessions view in the sysmaster database.
Statements such as "select count(*) from sysscblst" may take
several seconds to run during which time other threads may be
observed to wait on the session mutex. In addition advisory
messages may appear in the online message log:
Performance Advisory: Unable to get session latch.
Results: This can happen during high connectivity periods where
sessions are allocated and freed frequently.
Action: This can impact session and tenant limits processing and
low memory manager processing.
The thread performing the sysscblst query may frequently be in
the running state. The following is an example stack for the
thread:
yield_processor_mvp
mt_unlock_helper
mt_nxtscb
mt_prscblst
pstread
pst_rsread
rsread
fmread
readseq_single
gettupl
scan_next
next_row
group_open
prepselect
open_cursor
sql_open
sq_open
sqmain
In addition there may be delays in connecting new sessions or in
the disconnection of existing sessions whilst the query is
active. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* Users of Informix Server prior to 12.10.xC15 and 14.10.xC5. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Informix Server 12.10.xC15 (when available) or *
* 14.10.xC5. *
**************************************************************** |
| Local Fix: |
|
| Solution |
|
| Workaround |
****************************************************************
* USERS AFFECTED: *
* Users of Informix Server prior to 12.10.xC15 and 14.10.xC5. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Informix Server 12.10.xC15 (when available) or *
* 14.10.xC5. *
**************************************************************** |
| Comment |
Fixed in Informix Server 12.10.xC15 and 14.10.xC5. |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 11.09.2020
02.02.2021
02.02.2021 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
