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2430458 - Phantom spid holds a blocking latch on the data cache buffer - SAP ASE

Symptom

  • A phantom spid is holding a latch that blocks an active spid and in turn it blocks other spids.
  • Output from sp_who or sysprocesses shows a spid in 'latch sleep' (example truncated for clarity)

fid   spid    status
---   ------    --------------
0    1234    latch sleep

  • When trying to kill the spid, ASE log reports this cannot be done as it blocked on a latch held by aonther spid:

Killing spid: 1234 will not be immediate because it is waiting for a latch held by spid: 5678

  • Checking back in the ASE log for events on spid 5678 (the blocking spid) shows errors including 6103 and 821:

00:0008:00000:05678:2019/07/22 03:42:00.55 server WARNING: Pss 0x0x00002aac47de61b0 found with open sdes. pspid 5678 ...
00:0008:00000:05678:2019/07/22 03:42:00.55 server Error: 6103, Severity: 17, State: 1
00:0008:00000:05678:2019/07/22 03:42:00.55 server Unable to do cleanup for the killed process; received Msg 821.

  • Just before these errors, ASE prints one or several warning messages indicating the cache was undersized for the user defined tempdb:

The 4K memory pool of named cache tempdb_cache (cache id 10, cachelet id 30) is configured too small for current demands (state 1). Transaction progress may cease or response time may increase.

  • It is in the cache mentioned where the phantom spid holds a blocking latch on the buffer.


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Environment

  • SAP Adaptive Server Enterprise (ASE) 15.7 SP13x / SP140

Product

SAP Adaptive Server Enterprise 15.7

Keywords

CR799128, CR#799128, 799128, 6103, 821, cleanup, killed, attempt, unhash,  buffer, hashed , KBA , BC-SYB-ASE , Sybase ASE Database Platform (non Business Suite) , Bug Filed

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