2591144 - Undetected deadlock between dbcc checkalloc(sybsecurity) process and AUDIT PROCESS -- SAP ASE | SAP Knowledge Base Article

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2591144 - Undetected deadlock between dbcc checkalloc(sybsecurity) process and AUDIT PROCESS -- SAP ASE

Symptom

  • AUDIT PROCESS (with spid 11) was in 'latch sleep' and the status didn't change for a long time.
  • Another hanging process (with spid 1022) was running 'dbcc checkalloc(sybsecurity)' with status 'wait for object to be returned to pool'.
  • Auditing Queue object memory pool had no free object. "dbcc mempool('Auditing Queue',show)" or sybmon command "mmgrpools object brief Auditing Queue" might show 'mc_used' = 'audit queue size' value. Default value of configurable parameter 'audit queue size' = 100.
  • Dbcc latch or sybmon latch command might show an allocation buffer with latchowner of spid which was running 'dbcc checkalloc(sybsecurity)', e.g.

Buffers latched by process 1022:
        pss->platchedbufs[0]: 0x215d00f38
Buffer header for buffer 0x215d00f38 (Mass head)
    page=0x1fc5bd000 bdnew=0x19011a270 bdold=0x19011a270 bhash=0x215da5890
    bmass_next=0x215d00f38 bmass_prev=0x215d00f38 bdbid=31515                         <--- dbid of sybsecurity database
    bvirtpg= [ 0x215d00ff0 vpgdevno=23 vpvpn=215554 vdisk=0x19c7689d0 ]
    bmass_head=0x215d00f38 bmass_tail=0x215d00f38
    bcache_desc=0x1c7b805c8 (cache name='default data cache')
    bpool_desc=0x1c7b91ea0 bdbtable=0x1902935e0
    Mass bkeep=2 Mass bpawaited=1 Mass btripsleft=0 Mass btripsleft_orig=0
    bmass_size=4096 (4K pool) bunref_cnt=0
    bmass_stat=0x45111008 (0x40000000 (MASS_CLOCK_SEEN), 0x04000000 (MASS_DONT_DISCARD), 0x01000000 (MASS_BUFPIN
PLC), 0x00100000 (MASS_CHANGING), 0x00010000 (MASS_DIRTY), 0x00001000 (MASS_HASHED), 0x00000008 (MASS_KEPT))
    bbuf_stat=0x1 (0x00000001 (BUF_PG_REF))
    Buffer blpageno=353792 bpg_size=4k Mass blpageno=353792 (Buffer slot #: 0)
    bxls_pin=0x0 bxls_next=0x0 bspid=1022
    bxls_flushseq=193809070 bxls_pinseq=194048537 bcurrxdes=0x0
Latch and the wait queue:
Latch (address: 0x215d00f68)
        latchmode: 0x2 (EX_LATCH)
        latchowner: 1022                           
        latchnoofowners: 1
        latchwaitq: 0x1945b7080 latchwaitqt: 0x1945b7080

Latch wait queue:
LATCHWAIT struct at 0x1945b7080
Latch wait struct (at address=0x1945b7080) of Spid 11          <-- AUDIT PROCESS with spid=11 was waiting for an EX_LATCH
        Address of buffer being waited for=0x215d00f38
        lwqnext=0x0     lwmode=0x2 (EX_LATCH)
        lwstatus=0x1 (Sleeping) lwevent=0x1945b7080


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Environment

  • SAP Adaptive Server Enterprise (ASE) 15.7 SP132 and lower versions
  • SAP Adaptive Server Enterprise (ASE) 16.0 GA

Product

SAP Adaptive Server Enterprise 15.7

Keywords

AUDIT PROCESS latch sleep 'wait for object to be returned to pool' audit queue size 'dbcc checkalloc(sybsecurity)' undetected deadlock CR 777553 , KBA , BC-SYB-ASE , Sybase ASE Database Platform (non Business Suite) , Bug Filed

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