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2505376 - SAP IQ multiplex server hang in buffer manager functions

Symptom

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

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Environment

  • SAP IQ 16.0
  • SAP IQ 16.1

Product

SAP IQ 16.0 ; SAP IQ 16.1

Keywords

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

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