2505376 - SAP IQ multiplex server hang in buffer manager functions

In certain situations SAP IQ servers in a multiplex setup may appear to hang.
If one executes 2-3 pstacks on the IQ Server process id at about 3 mins apart, one can find stacks with following threads that could indicate the deadlock scenario

• Scenario 1:
  
  Threads (1): 140103113127680
  hos_rmutex::Lock
  s_VersioningBlockmap::LockRFRB
  s_VersioningBlockmap::Reallocate
  s_buf::DirtyInternal
  s_buf::DirtyBlockmapPage
  s_blockmap::VersionSBuf
  s_blockmap::GetSBuf
  s_blockmap::RegisterPhysicalBlockId
  s_blockmap::AllocOrReallocPhysicalBlocks
  s_buf::Write
  ...
  
  Threads (1): 140103083009792
  s_bufman::FindBlockMap1
  s_dbmvbio::SecondaryProxyOutOfSpaceHandler
  s_dbmvbio::Allocate
  s_VersioningBlockmap::Allocate
  s_blockmap::AllocOrReallocPhysicalBlocks
  s_buf::Write
  ...
• Scenario 2:
  
  Threads (1): 3213
  hos_condvar::Wait() const
  s_buf::WaitForSignal_DontCareIfBusy()
  s_bufhash::Find
  s_bufpartition::Find
  s_blockmap::GetSBuf
  s_blockmap::GetSizeInfo
  db_BlockCountHandler::operator()
  hs_dp::VisitBlockmaps
  db_IndexDef::VisitBlockmaps
  db_Catalog::VisitBlockmaps
  db_TableSizeCursor::Fetch
  st_command::DoCmdThroughResourceGate()
  db_iqddl::IQUtilityFetch
  UIQDDL_IQUtilityFetch
  
  Threads (1): 1271
  s_blockmap::RegisterPhysicalBlockId
  s_blockmap::AllocOrReallocPhysicalBlocks
  s_buf::Write
  s_blockmap::HelperFlush
  s_commitRequest::Perform
  s_cacheTeamWorkIter::ExecWork

• SAP IQ 16.0
• SAP IQ 16.1

 Sybase , CR809642 , CR#809642 , deadlock, hang , freeze, bugzilla 154803 , bugzilla 154804 , KBA , BC-SYB-IQ , Sybase IQ , Bug Filed