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2735915 - CHECKPOINT is blocked by a phantom process killed with 'force' when a temp database ran out of log space - SAP ASE

Symptom

  • A temporary database logsegment is full. 
  • The last threshold procedure is activated:   

Space available in segment 'logsegment' has fallen critically low in database 'mytempdb'. All future modifications to this database will be suspended until the transaction log is successfully dumped and space becomes available.

  • Some user processes using mytempdb are killed with the 'force' option but their termination cannot be completed cleanly due to the out-of-space condition in the mytempdb log. 
     
  • The CHECKPOINT process is impacted. It is in the "lock sleep" status and blocked by a killed with 'force' and no longer existing user process which left phantom locks behind:

fid            spid          status       loginame  origname hostname blk_spid   dbname   tempdbname           cmd               block_xloid               threadpool
0              10            lock sleep [NULL]      [NULL]      [NULL]      746    mytempdb       tempdb    CHECKPOINT SLEEP   0              syb_default_pool

  • Using the dbcc lock_release command releases phantom locks, but it has no affect on the CHECKPOINT status.
     
  • The mytemp database cannot be rebooted using the dbcc dbreboot command because it is being in use by the active CHECKPOINT process:  

---------- Shutting Down Database 'mytempdb' ----------
---------- Active Processes and Transactions in Database 'mytempdb' ----------
  Spid Program      Transaction      Status          CPU     I/O         Blk  Error
    10                $dmpxact         lock sleep        0 170070201    746      0

  • Killing processes with 'force' when the temp database is running out of log space can also result in Errors 1251 and 6103:

Error: 1251, Severity: 26, State: 1
An in-use preallocated semaphore cursor was encountered.
 
Error: 6103, Severity: 17, State: 1
Unable to do cleanup for the killed process; received Msg 3300.

  • The temporary database is a mixed data and log database.
  • ASE has to be rebooted.


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Environment

  • SAP Adaptive Server Enterprise (ASE) 15.7
  • SAP Adaptive Server Enterprise (ASE) 16.0

Product

SAP Adaptive Server Enterprise 15.7 ; SAP Adaptive Server Enterprise 16.0

Keywords

CR817697, CR#817697, 817697, kill, force, zombie , KBA , BC-SYB-ASE , Sybase ASE Database Platform (non Business Suite) , Bug Filed

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