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IZ43156: ERROR "EXPECTED LATCH TO BE HELD" FOLLOWED BY A DB2 ABEND

Fixes are available

DB2 Version 9.1 Fix Pack 8  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 9  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 10  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 11  for Linux, UNIX and Windows
DB2 Version 9.1 Fix Pack 12  for Linux, UNIX and Windows

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APAR status

  • Closed as program error.

Error description

  • Error "Expected latch to be held" followed by a DB2 abend.

The error "Expected latch to be held" is reported in the
db2diag.log indicating that bufferpool services was not able to
find an expected latch.

The following entries may appear in the db2diag log file:

2009-01-03-10.47.55.921983-480 I181512511A437 LEVEL: Error
PID : 28986 TID : 47 PROC : db2sysc 0
INSTANCE: db2inst1 NODE : 000
EDUID : 47 EDUNAME: db2pfchr (SAMPLE) 0
FUNCTION: DB2 UDB, buffer pool services,
sqlbReadAndReleaseBlock, probe:120
MESSAGE : ZRC=0x87020036=-2029912010=SQLB_BADHDR "Bad Page
Header"
DIA8547C An error occurred in a database page header.

2009-01-03-10.47.55.938946-480 E181513297A2121 LEVEL: Severe
(OS)
PID : 28986 TID : 47 PROC : db2sysc 0
INSTANCE: db2inst1 NODE : 000
EDUID : 47 EDUNAME: db2pfchr (SAMPLE) 0
FUNCTION: DB2 UDB, SQO Latch Tracing,
SQLO_SLATCH_CAS64::releaseConflictComple, probe:330
MESSAGE :
ZRC=0x870F011E=-2029059810=SQLO_LATCH_ERROR_EXPECTED_HELD
"expected latch to be held."

CALLSTCK:
[0] 0xFFFFFFFF7C86D4B8
__1cRSQdDLO_SLATCH_CAS64WreleaseConflictComplex6M_v_ + 0x6A8
[1] 0xFFFFFFFF7B181FA0
__1cXsqlbReadAndReleaseBlock6FpnLSQdDLB_FIX_CB_pnUSQdDLB_BLOCK_V
ICTIM_CB_IpnLSQdDLB_pfMisc__i_ + 0xB90
[2] 0xFFFFFFFF7B17EA3C
__1cQsqlbProcessRange6FpnQSQdDLB_OBJECT_DESC_IIpnLSQdDLB_pfMisc
_i_ + 0x50C
[3] 0xFFFFFFFF7B17EE0C
__1cXsqlbServiceRangeRequest6FpnLSQdDLB_pfMisc__i_ + 0x174
[4] 0xFFFFFFFF7B17AC88 __1cbAsqlbPFPrefetcherEntryPoint6FpcI_v
+ 0x9F8
[5] 0xFFFFFFFF7C917A24 sqloEDUEntry + 0x3A4
[6] 0xFFFFFFFF777D266C _thr_slot_offset + 0x484
[7] 0x0000000000000000 ?unknown + 0x0
[8] 0x0000000000000000 ?unknown + 0x0
[9] 0x0000000000000000 ?unknown + 0x0

The symptoms when this issue can happen:

1. "BAD PAGE" message is not always present when the issue is
encountered.

2. When block based bufferpools are used


3. When there are a lot of concurrent activities against the
bufferpools

Local fix

  • Disable block based bufferpools:

DB2 ALTER BUFFERPOOL <buff_pool_name> NUMBLOCKPAGES 0

OR

The fix for IZ20119 reduces the likelihood of running into
this problem.

or

Tune block based bufferpools.

Problem summary

  • Users Affected: All
Problem Description:
The error "Expected latch to be held" is reported in the
db2diag.log indicating that bufferpool services was not able to
find an expected latch.

The following entries may appear in the db2diag log file:

2009-01-03-10.47.55.921983-480 I181512511A437 LEVEL: Error
PID : 28986 TID : 47 PROC : db2sysc 0
INSTANCE: db2inst1 NODE : 000
EDUID : 47 EDUNAME: db2pfchr (SAMPLE) 0
FUNCTION: DB2 UDB, buffer pool services,
sqlbReadAndReleaseBlock, probe:120
MESSAGE : ZRC=0x87020036=-2029912010=SQLB_BADHDR "Bad Page
Header"
DIA8547C An error occurred in a database page header.

2009-01-03-10.47.55.938946-480 E181513297A2121 LEVEL: Severe
(OS)
PID : 28986 TID : 47 PROC : db2sysc 0
INSTANCE: db2inst1 NODE : 000
EDUID : 47 EDUNAME: db2pfchr (SAMPLE) 0
FUNCTION: DB2 UDB, SQO Latch Tracing,
SQLO_SLATCH_CAS64::releaseConflictComple, probe:330
MESSAGE :
ZRC=0x870F011E=-2029059810=SQLO_LATCH_ERROR_EXPECTED_HELD
"expected latch to be held."

CALLSTCK:
[0] 0xFFFFFFFF7C86D4B8
__1cRSQdDLO_SLATCH_CAS64WreleaseConflictComplex6M_v_ + 0x6A8
[1] 0xFFFFFFFF7B181FA0
__1cXsqlbReadAndReleaseBlock6FpnLSQdDLB_FIX_CB_pnUSQdDLB_BLOCK_V
ICTIM_CB_IpnLSQdDLB_pfMisc__i_ + 0xB90
[2] 0xFFFFFFFF7B17EA3C
__1cQsqlbProcessRange6FpnQSQdDLB_OBJECT_DESC_IIpnLSQdDLB_pfMisc
_i_ + 0x50C
[3] 0xFFFFFFFF7B17EE0C
__1cXsqlbServiceRangeRequest6FpnLSQdDLB_pfMisc__i_ + 0x174
[4] 0xFFFFFFFF7B17AC88 __1cbAsqlbPFPrefetcherEntryPoint6FpcI_v
+ 0x9F8
[5] 0xFFFFFFFF7C917A24 sqloEDUEntry + 0x3A4
[6] 0xFFFFFFFF777D266C _thr_slot_offset + 0x484
[7] 0x0000000000000000 ?unknown + 0x0
[8] 0x0000000000000000 ?unknown + 0x0
[9] 0x0000000000000000 ?unknown + 0x0

The symptoms when this issue can happen:

1. "BAD PAGE" message is not always present when the issue is
encountered.

2. When block based bufferpools are used


3. When there are a lot of concurrent activities against the
bufferpools

Problem Summary:
The error "Expected latch to be held" is reported in the
db2diag.log indicating that bufferpool services was not able to
find an expected latch.

The following entries may appear in the db2diag log file:

2009-01-03-10.47.55.921983-480 I181512511A437 LEVEL: Error
PID : 28986 TID : 47 PROC : db2sysc 0
INSTANCE: db2inst1 NODE : 000
EDUID : 47 EDUNAME: db2pfchr (SAMPLE) 0
FUNCTION: DB2 UDB, buffer pool services,
sqlbReadAndReleaseBlock, probe:120
MESSAGE : ZRC=0x87020036=-2029912010=SQLB_BADHDR "Bad Page
Header"
DIA8547C An error occurred in a database page header.

2009-01-03-10.47.55.938946-480 E181513297A2121 LEVEL: Severe
(OS)
PID : 28986 TID : 47 PROC : db2sysc 0
INSTANCE: db2inst1 NODE : 000
EDUID : 47 EDUNAME: db2pfchr (SAMPLE) 0
FUNCTION: DB2 UDB, SQO Latch Tracing,
SQLO_SLATCH_CAS64::releaseConflictComple, probe:330
MESSAGE :
ZRC=0x870F011E=-2029059810=SQLO_LATCH_ERROR_EXPECTED_HELD
"expected latch to be held."

CALLSTCK:
[0] 0xFFFFFFFF7C86D4B8
__1cRSQdDLO_SLATCH_CAS64WreleaseConflictComplex6M_v_ + 0x6A8
[1] 0xFFFFFFFF7B181FA0
__1cXsqlbReadAndReleaseBlock6FpnLSQdDLB_FIX_CB_pnUSQdDLB_BLOCK_V
ICTIM_CB_IpnLSQdDLB_pfMisc__i_ + 0xB90
[2] 0xFFFFFFFF7B17EA3C
__1cQsqlbProcessRange6FpnQSQdDLB_OBJECT_DESC_IIpnLSQdDLB_pfMisc
_i_ + 0x50C
[3] 0xFFFFFFFF7B17EE0C
__1cXsqlbServiceRangeRequest6FpnLSQdDLB_pfMisc__i_ + 0x174
[4] 0xFFFFFFFF7B17AC88 __1cbAsqlbPFPrefetcherEntryPoint6FpcI_v
+ 0x9F8
[5] 0xFFFFFFFF7C917A24 sqloEDUEntry + 0x3A4
[6] 0xFFFFFFFF777D266C _thr_slot_offset + 0x484
[7] 0x0000000000000000 ?unknown + 0x0
[8] 0x0000000000000000 ?unknown + 0x0
[9] 0x0000000000000000 ?unknown + 0x0

The symptoms when this issue can happen:

1. "BAD PAGE" message is not always present when the issue is
encountered.

2. When block based bufferpools are used


3. When there are a lot of concurrent activities against the
bufferpools

Problem conclusion

  • Problem first fixed in version 9.1 Fixpak 8

Temporary fix

  • Disable block based bufferpools:

DB2 ALTER BUFFERPOOL <buff_pool_name> NUMBLOCKPAGES 0

OR

The fix for IZ20119 reduces the likelihood of running into
this problem.

or

Tune block based bufferpools.

Comments

  • 



APAR Information




    

  • APAR number
    IZ43156
    • 

  • Reported component name
    DB2 UDB ESE SOL
    • 

  • Reported component ID
    5765F4102
    • 

  • Reported release
    910
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Special Attention
    NoSpecatt
    • 

  • Submitted date
    2009-02-03
    • 

  • Closed date
    2009-05-05
    • 

  • Last modified date
    2009-05-05
    • 





    

  • APAR is sysrouted FROM one or more of the following:
    

    
IZ43149
    

    • 

  • APAR is sysrouted TO one or more of the following:
    

    • 



Fix information


    

  • Fixed component name
    DB2 UDB ESE SOL
    • 

  • Fixed component ID
    5765F4102
    • 



Applicable component levels


    

  • R910  PSY
       UP
    • 








      
              
                            

              

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Document Information


            

            


                        

            Modified date:
            

            05 May 2009
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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