Import is using the SYSIBMADM.DBCFG interface to get config
parameter values from all partitions just in case the db config
is not the same on all partitions in DPF environment , so the
selecting from SYSIBMADM.DBCFG broadcast the request to all
nodes to get data. When all nodes got the request, they all need
to access GLFH file each will acquire latch and then lock the
file. When multiple concurrent Import all query at the same
time, this may cause massive contention on the same file lock,
and db2 may hang there .
we will see repeat invoking of statement like :
SELECT SUBSTR(value, 1, 20) FROM SYSIBMADM.DBCFG WHERE name =
CAST('decflt_rounding' AS VARCHAR(15))
Also we can see from db2pd -api that both last sql statement
and current sql statment is same selecting from SYSIBMAMD.DBCFG
AnchID StmtUID NumEnv NumVar NumRef NumExe
Text
873 1087 1 1 364 364
SELECT SUBSTR(value, 1, 20) FROM SYSIBMADM.DBCFG WHERE name =
CAST('decflt_rounding' AS VARCHAR(15))
621 7502 1 1 366 366
SELECT VALUE FROM SYSIBMADM.DBCFG WHERE NAME =
'varchar2_compat'
The stack will be like :
_syscall6(0xfffffffcec3ebb20,0xffffffff7eaa91f0,0x2,0xffffffffff
ffffff,0xfffffffcec3eb9c4,0x1002f4360) + 0x20
__pos4obj_unlink(0xfffffffcec3ebb20,0xffffffff7eaa91f0,0x2,0xfff
fffffffffffff,0xfffffffcec3eb9c4,0x1002f4360) + 0x24
sem_open(0xfffffffcec3ebb20,0x0,0x0,0x1593d4,0x0,0x0) + 0x3dc
__1cSOSSHIPCSemaphoreExGcreate6MkpknbCOSSIPCSemaphoreExCreatePar
am__I_(0xfffffffcec3ec0d8,0xfffffffcec3ec0a8,0x0,0x4b5400,0xffff
ffffffffffff,0xfffffffcec3ebb21) + 0x250
__1cVsqlnlsGetCCInfoFromCC6FL_pknPsqlnls_cc_table__(0xfffffffcec
3ecf98,0x0,0x40001,0xfffffffcec3ec218,0x1b0,0xfffffffcec3ec0d8)
+ 0x3a50
sqloNLCKUnlock(0xfffffffcec3ecf98,0xfffffffcec3fffff,0x4f40634,0
x3632800,0x40001,0x40000) + 0x244
__1cMSQdDLP_GLFH_CBGunlock6M_i_(0xfffffffcec3ecf70,0xffffffff665
7d870,0x4e07f4c,0x18800000,0x40000,0x3632b28) + 0x80
__1cOsqlpgCloseGLFH6FpnMSQdDLP_GLFH_CB__i_(0xfffffffcec3ecf70,0x
0,0x4e192dc,0x3632800,0xffffffff62f4ad48,0x40000) + 0xe4
__1cTsqlpBuildParmsNoDPS6FpknIsqeAgent_pkc4iIIpIII5pnNSQdDLP_LH_
PARMS__i_(0x0,0xfffffffcec3f3168,0x201752861,0x1,0x3,0xfffffffce
c3effc8) + 0x694
__1cIsqlpglhu6FpknIsqeAgent_pkc4iIIpIII5pnNSQdDLP_LH_PARMS__i_(0
x0,0x201752861,0x0,0x0,0xfffffffcec3f3ec0,0x0) + 0x580
__1cIsqlfgtlp6FIpvpI1pkcpc_i_(0x2,0x0,0xfffffffcec3f3ec4,0xfffff
ffcec3f3ec0,0x201752861,0xfffffffcec3f3fec) + 0x12c
__1cYsqlfInitDbCfgParamForGet6Fpc00kipnLdb2CfgParam_pnKsqlf_dbcf
d_pnFsqlca_ipnQsqeLocalDatabase__i_(0xfffffffcfdb0bff0,0x0,0x70,
0xffffffff60a1c0b5,0x1000,0x201752968) + 0x350
__1cMsqlfGetDbCfg6FpnQsqeLocalDatabase_pnGdb2Cfg_ipnFsqlca__i_(0
x201750080,0xfffffffcec3fc318,0x201752861,0x202899368,0x40000,0x
0) + 0x96c
__1cQsqlrwGetDBConfig6FpnIsqlrr_cb_pnUsqlrwGetDBConfigArgs_ppvpl
_i_(0xffffffff7516a420,0xffffffff365623f0,0xfffffffcec3fc4f8,0xf
ffffffcec3fc4f0,0x0,0x0) + 0x128
__1cbEsqlrwGetWLMTableFunctionResult6FpnIsqlrr_cb_pnUsqlrw_rpc_t
f_request_ppvplb_i_(0xffffffff7516a420,0xffffffff365623f0,0xffff
fffcec3fc4f8,0xfffffffcec3fc4f0,0xffffffff5e882bb0,0x70) +
0x48c |
