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2804360 - IQ server thread could hang while performing a LOAD TABLE under specific conditions when the system is under heavy CPU load – SAP IQ

Symptom

  • Under specific conditions when the system is under heavy CPU load an IQ server thread could hang while performing a LOAD TABLE

  • The issue is random and unpredictable. So far this has only been seen when running several concurrent large LOAD jobs on a Writer node in a multiplex system, where the LOAD statement uses multiple input files.

  • Stack traces of the hung thread can show these calls...

  .. __do_global_dtors_aux_fini_array_entry
  .. hos_condvar::Wait()
  .. hos_team::StartWork(void
  .. hos_team::Exec(hos_workIter&)
  .. dfo_Scheduler::FetchOpus()
  .. dfo_Root::FetchOpus()
  .. dfo::Fetch()
  .. db_dmlcommand::ExecuteDFOTree()
  .. db_LoadTable::Execute()
  .. st_command::DoCmdThroughResourceGate()
  .. st_iqdml::Load(a_statement*, UIConnection
  .. UIQDML_Load
  ...

  • The hung LOAD transaction can go on to cause a version build up within the IQ server over a period of time and may lead to a server wide hang or crash if left unresolved.

  • The stuck LOAD can be manually cancelled and resubmitted to resolve.


Read more...

Environment

  • SAP IQ 16.1 SP*

  • SAP IQ 16.0 SP11

  • So far this has been reported on Solaris and Linux but is not expected to be platfrom specific

Product

SAP IQ 16.0 ; SAP IQ 16.1

Keywords

'Load hang', 'session hang', CR819327, 819327, sybase, blocked, stuck, fail, insert, loadtable, slow, performance, crash, abort, pstack, unix, mpx, multiplex, 'multi plex'   , KBA , BC-SYB-IQ , Sybase IQ , Problem

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