This memory leak is specific to using a UCA500R1 collation
sequence database in conjunction with a LIKE predicate that uses
column name in pattern expression.
Example of the syntax: LIKE(MyCol || '%').
This type of LIKE pattern expression is supported since version
9.7 Fixpack 4.
You can identify the leak in PRIVATE memory using the db2pd tool
:
DB2SYSC=`db2pd -edu | grep "db2sysc PID:" | awk '{ print $3}'`
db2pd -dbptnmem > dbptnmem.1.out
db2pd -memb pid=$DB2SYSC > memb.1.out
db2 "select * from MySchema.MyTable WHERE COALESCE(MyCol_1,'')
LIKE (MyCol_2 || '%')"
db2pd -dbptnmem > dbptnmem.2.out
db2pd -memb pid=$DB2SYSC > memb.2.out
After the running the statement, the size of PRIVATE MEMORY will
show an increase in PRIVATE memory that could be consequent
depending on the result set (you can compare the 2 output files
generated as above : dbptnmem.*.out) :
=== BEFORE EXECUTION ===
Database Partition Memory Controller Statistics
Controller Automatic: N
Memory Limit: 4000000 KB
Current usage: 341376 KB
HWM usage: 341376 KB
Cached memory: 175296 KB
Individual Memory Consumers:
Name Mem Used (KB) HWM Used (KB) Cached (KB)
========================================================
APPL-FOD 160000 160000 158848
DBMS-dbguest0 48448 48448 0
FMP_RESOURCES 22528 22528 0
PRIVATE 9344 9344 0
LCL-p21517 128 128 0
DB-FOD 100928 100928 16448
=== AFTER EXECUTION ===
Database Partition Memory Controller Statistics
Controller Automatic: N
Memory Limit: 4000000 KB
Current usage: 2590208 KB
HWM usage: 2595200 KB
Cached memory: 175296 KB
Individual Memory Consumers:
Name Mem Used (KB) HWM Used (KB) Cached (KB)
========================================================
APPL-FOD 160000 160000 158848
DBMS-dbguest0 48384 48384 0
FMP_RESOURCES 22528 22528 0
PRIVATE 2258240 2258240 0
LCL-p20550 128 128 0
DB-FOD 100928 100928 16448
This memory leak can lead to a SEGV in sqlvCCCBuildNextLikeRule
or sqlnlsStringSearch_open_ICUbug_U500R1 if the leak grows over
INSTANCE_MEMORY. In such case the trap will show a stack similar
to this one :
PC location:
__1cYsqlvCCCBuildNextLikeRule6FpnIsqlrr_cb_pknOsqlrxCollation_pp
nPsqlvCCCLikeRule_6pCi8iipi_i_ + 0x11a8
Object file: /opt/IBM/db2/V9.7B/lib64/libdb2e.so.1 (offset
0x4a11f48)
</Registers>
<StackTrace>
##### Object: /opt/IBM/db2/V9.7B/lib64/libdb2e.so.1
__1cYsqlvCCCBuildNextLikeRule6FpnIsqlrr_cb_pknOsqlrxCollation_pp
nPsqlvCCCLikeRule_6pCi8iipi_i_(0xffffffff8b0f0001,0xffffffff6229
6d18,0x18b00000,0xb6c00,0xfffffffccd7f59f0,0x870f0000) + 0x11a8
__1cbCsqlriCCCLikeComputeRulesCore6FpnIsqlrr_cb_pnKsqlz_value_3p
nUsqlriCCCLikeWorkArea__i_(0xffffffff4beccba0,0x2,0x0,0xffffffff
633b2728,0x0,0x1) + 0xa8c
__1cYsqlriCCCLikeComputeRules6FpnIsqlrr_cb__i_(0xffffffff4beccba
0,0x0,0x276823c,0x2,0xc8000,0xffffffff7c85a2c0) + 0x58
__1cQsqldEvalDataPred6FpnNSQdDLD_DFM_WORK_pLpnKSQdDLD_DPRED__i_(
0xffffffff63ee3710,0xfffffffccd7f6008,0xffffffff633b26b8,0x1788,
0xffffffff633b2cd0,0xf808600220800) + 0x140
__1cMsqldReadNorm6FpnNSQdDLD_DFM_WORK_l_i_(0xffffffff63ee3710,0x
1e,0x6,0xffffffff63ee3888,0x1,0x0) + 0x1734
__1cPsqldFetchDirect6FpnNSQdDLD_DFM_WORK__i_(0xffffffff63ee3710,
0x0,0xffffffff63ee3788,0xffffffff63ee38d8,0x0,0xffffffff63ee3888
) + 0x4740
__1cHsqldfrd6FpnNSQdDLD_DFM_WORK__i_(0xffffffff63ee3710,0x205800
1f,0xf808600220800,0xfffffffec316c000,0x0,0x1f) + 0x1040
__1cMsqldRowFetch6FpnIsqeAgent_pnISQdDLD_CCB_LLppnKSQdDLD_VALUE_
pnISQdDLZ_RID_LpnMSQdDLD_ID_LIST_pnJSQdDLP_LSN8__i_(0x8,0xffffff
ff7c85a2c0,0xffffffff63ee3710,0xfffe,0x0,0xffffffff633b21f0) +
0x1f84 |
