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

• 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.

• 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

'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