|
Problem IT16969
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Status: Closed |
SESSIONS MAY BECOME BLOCKED WAITING ON DDH CHAIN MUTEX WHEN USING UPDATEABLE SECONDARY SERVERS
|
| product: |
INFORMIX SERVER / 5725A3900 / C10 - IDS 12.10 |
| Problem description: |
Sessions on a primary server may become blocked waiting on a ddh
chain mutex when the processing of an update request from a
secondary server fails. The output of the command "onstat -g
wmx" may show a list of waiting threads with long wait times,
for example:
Mutexes with waiters:
mid addr name holder lkcnt
waiter waittime
3593 700000026c64ca0 ddh chain 13 0 1
6562215 38662
6562234 38654
6563470 38361
6564184 38182
6564212 38176
...
There may be several causes of this problem. One such cause is
indicated by an error message in the online log at around the
time of the first thread starting to wait on the mutex:
Encountered problem processing update on secondary : Cannot read
row db:informix.tab1
partnum:rowid 19922953:0x2055 SQL:0 ISAM:12225
This message and the ISAM error 12225 indicate a problem
searching the data dictionary cache for the given table. When a
valid entry cannot be located the proxy thread performing the
operation fails to clean up correctly leaving the mutex in a
locked state. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* Rare condition with updateable secondary server in a *
* replication system. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Update to IBM Informix Server 12.10.xC8 or later. *
**************************************************************** |
| Local Fix: |
To help avoid this issue ensure the size of the data dictionary
cache is large enough to allow all tables to have a valid entry. |
| Solution |
|
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 08.09.2016
09.12.2016
09.12.2016 |
| Problem solved at the following versions (IBM BugInfos) |
12.10.xC8
|
| Problem solved according to the fixlist(s) of the following version(s) |
