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2369714 - An IQ server is very slow and seems unresponsive while executing a long checkpoint.

Symptom

A simplex IQ server was suddenly very slow and seems unresponsive.

1. message log
According to the message log, it seems like the IQ server wasn't in a complete unresponsive status.
The unresponsive status had started at 13:53:03, but the below pattern was repeatedly logged in IQ message until the IQ server got restarted 4 hours later.
So, it's a little different from the typical HANG status.

I. 09/12 13:53:03. 0002677689 Txn 541447579 0 541447579
I. 09/12 13:53:03. 0002677689 Cmt 541447580
I. 09/12 13:53:03. 0002677689 PostCmt 0
I. 09/12 13:53:04. 0000000013 Txn 541447581 0 541447581
I. 09/12 13:53:04. 0000000013 Cmt 541447582
I. 09/12 13:53:04. 0000000013 PostCmt 0
I. 09/12 13:53:04. 0000000013 Txn 541447583 0 541447583
I. 09/12 13:53:04. 0000000013 Cmt 541447584
I. 09/12 13:53:04. 0000000013 PostCmt 0
I. 09/12 13:53:04. 0000000013 Txn 541447585 0 541447585
I. 09/12 13:53:04. 0002677690 Collation 936ZHO, Case Respect, Blank Padding On, Comparisons are Conditioned
I. 09/12 13:53:04. 0002677690 Txn 541447586 0 541447586
I. 09/12 13:53:04. 0002677690 Connect: SA connHandle: 2121498 SA connID: 84 IQ connID: 0002677690 User: dba

2. srvlog
I. 09/12 13:53:00. Insert Pass 2 completed in 0 seconds.
I. 09/12 13:53:00.
296 records were inserted into 'A_R_9_CELL_HD_HO'.
I. 09/12 13:53:00. Insert for 'A_R_9_CELL_HD_HO' completed in 3 seconds. 296 rows inserted.
I. 09/12 14:35:05. Starting checkpoint of "zdc" (zdc.db) at Mon Sep 12 2016 14:35
I. 09/12 14:35:06. Finished checkpoint of "zdc" (zdc.db) at Mon Sep 12 2016 14:35
I. 09/12 15:15:07. Starting checkpoint of "zdc" (zdc.db) at Mon Sep 12 2016 15:15
I. 09/12 15:15:09. Finished checkpoint of "zdc" (zdc.db) at Mon Sep 12 2016 15:15
I. 09/12 15:55:07. Starting checkpoint of "zdc" (zdc.db) at Mon Sep 12 2016 15:55
I. 09/12 15:55:09. Finished checkpoint of "zdc" (zdc.db) at Mon Sep 12 2016 15:55
I. 09/12 16:27:07. Connection terminated abnormally
I. 09/12 16:27:07. Disconnected SharedMemory client's AppInfo: IP=.............................
I. 09/12 16:32:50. Connection terminated abnormally
I. 09/12 16:32:50. Disconnected SharedMemory client's AppInfo: IP=.............................
I. 09/12 16:33:59. Connection terminated abnormally
I. 09/12 16:33:59. Disconnected SharedMemory client's AppInfo: IP=.............................
.............................
.............................
I. 09/12 17:55:22. Starting checkpoint of "zdc" (zdc.db) at Mon Sep 12 2016 17:55
I. 09/12 17:55:24. Finished checkpoint of "zdc" (zdc.db) at Mon Sep 12 2016 17:55
I. 09/12 17:55:27. Database server stopped at Mon Sep 12 2016 17:55

When the issue happened, the IQ server had more than 180 user connections.
Connections via dbisql during issue were established and some commands could be run, some could not be run, for example running sp_iqdbspace has no output.

3. pstack dumps.
Most of the threads in pstack dumps contains the keyword "st_command::SeizeResourceGate()"
So, it looks like this problem is related with the exhaustion of resources at that time.

in hos_condvar::Wait() const
in st_command::SeizeResourceGate()
in st_command::DoCmdThroughResourceGate()
in st_iqdml::Insert(.......................
in UIQDML_Insert
in st_SAIQInterfaceInfo::callFunction()
in st_SAIQInterface::RunIQFunc(.......................
in st_SAIQInterface::Execute(.......................
in saint_iqthresholddml::Insert(.......................
in dbi_insert(.......................
in dbi_tsql_select_into(.......................
in DoExecuteStmt(.......................


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Environment

SAP IQ 15.4.0.3046/141204/P/ESD 5/Enterprise Linux64 - x86_64

Product

SAP Sybase IQ 15.4

Keywords

SAP IQ, IQ, slow, SeizeResourceGate, 802207, CR802207, CR 802207, iqgovern, checkpoint , KBA , BC-SYB-IQ , Sybase IQ , Problem

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