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1丶查出当前会话所对应的系统进程号：SPID=7376，如下语句（在第一个窗口执行）
gyj@OCM> select spid from v$session s,v$process p where s.paddr=p.addr and sid in(select distinct sid from v$mystat);
SPID
------------------------
7376
2丶 通过系统进程号7376打开gdb程序（在第二个窗口执行）
[oracle@mydb ~]$ gdb $ORACLE_HOME/bin/oracle 7376
GNU gdb Fedora (6.8-27.el5)
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu"...
(no debugging symbols found)
Attaching to program: /u01/app/oracle/product/11.2.0/bin/oracle, process 7376
Reading symbols from /u01/app/oracle/product/11.2.0/lib/libodm11.so...(no debugging symbols found)...done.
Loaded symbols for /u01/app/oracle/product/11.2.0/lib/libodm11.so
Reading symbols from /u01/app/oracle/product/11.2.0/lib/libcell11.so...done.
Loaded symbols for /u01/app/oracle/product/11.2.0/lib/libcell11.so
Reading symbols from /u01/app/oracle/product/11.2.0/lib/libskgxp11.so...done.
Loaded symbols for /u01/app/oracle/product/11.2.0/lib/libskgxp11.so
Reading symbols from /lib64/librt.so.1...done.
Loaded symbols for /lib64/librt.so.1
Reading symbols from /u01/app/oracle/product/11.2.0/lib/libnnz11.so...done.
Loaded symbols for /u01/app/oracle/product/11.2.0/lib/libnnz11.so
Reading symbols from /u01/app/oracle/product/11.2.0/lib/libclsra11.so...done.
Loaded symbols for /u01/app/oracle/product/11.2.0/lib/libclsra11.so
Reading symbols from /u01/app/oracle/product/11.2.0/lib/libdbcfg11.so...done.
Loaded symbols for /u01/app/oracle/product/11.2.0/lib/libdbcfg11.so
Reading symbols from /u01/app/oracle/product/11.2.0/lib/libhasgen11.so...done.
Loaded symbols for /u01/app/oracle/product/11.2.0/lib/libhasgen11.so
Reading symbols from /u01/app/oracle/product/11.2.0/lib/libskgxn2.so...done.
Loaded symbols for /u01/app/oracle/product/11.2.0/lib/libskgxn2.so
Reading symbols from /u01/app/oracle/product/11.2.0/lib/libocr11.so...done.
Loaded symbols for /u01/app/oracle/product/11.2.0/lib/libocr11.so
Reading symbols from /u01/app/oracle/product/11.2.0/lib/libocrb11.so...done.
Loaded symbols for /u01/app/oracle/product/11.2.0/lib/libocrb11.so
Reading symbols from /u01/app/oracle/product/11.2.0/lib/libocrutl11.so...done.
Loaded symbols for /u01/app/oracle/product/11.2.0/lib/libocrutl11.so
Reading symbols from /usr/lib64/libaio.so.1...done.
Loaded symbols for /usr/lib64/libaio.so.1
Reading symbols from /lib64/libdl.so.2...done.
Loaded symbols for /lib64/libdl.so.2
Reading symbols from /lib64/libm.so.6...done.
Loaded symbols for /lib64/libm.so.6
Reading symbols from /lib64/libpthread.so.0...done.
[Thread debugging using libthread_db enabled]
[New Thread 0x2b0b8fef0910 (LWP 7376)]
Loaded symbols for /lib64/libpthread.so.0
Reading symbols from /lib64/libnsl.so.1...done.
Loaded symbols for /lib64/libnsl.so.1
Reading symbols from /lib64/libc.so.6...done.
Loaded symbols for /lib64/libc.so.6
Reading symbols from /lib64/ld-linux-x86-64.so.2...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
Reading symbols from /usr/lib64/libnuma.so.1...done.
Loaded symbols for /usr/lib64/libnuma.so.1
Reading symbols from /lib64/libnss_files.so.2...done.
Loaded symbols for /lib64/libnss_files.so.2
Reading symbols from /u01/app/oracle/product/11.2.0/lib/libnque11.so...done.
Loaded symbols for /u01/app/oracle/product/11.2.0/lib/libnque11.so
0x0000003f0d40d290 in __read_nocancel () from /lib64/libpthread.so.0
(gdb)
3丶设一个断点，持有第一个Latch锁(预先知道函数kslgetl就是持有Latch的函数)，并运行（c命令，即continue）（在第二个窗口执行）
(gdb) b kslgetl
Breakpoint 1 at 0x8f96376
(gdb) c
Continuing.
4丶执行一个update语句，触发断点的操作，此时update被阻塞了（在第一个窗口执行）
gyj@OCM> update gyj_test set name=\'AAAAA\' where id=1;
5丶一执行updater操作，断点就停在这儿了（在第二个窗口执行）
Breakpoint 1, 0x0000000008f96376 in kslgetl ()
(gdb)
6丶我们先来看update时持有第一个Latch锁所对应函数kslgetl ()的第一个参数是什么？用命令info all-register显示寄存器（在第二个窗口执行）
(gdb) info all-register
rax 0x0 0
rbx 0x2000 8192
rcx 0xf27 3879
rdx 0x0 0
rsi 0x1 1
rdi 0x601082f0 1611694832
rbp 0x7fff1c5754d0 0x7fff1c5754d0
rsp 0x7fff1c5754d0 0x7fff1c5754d0
r8 0xf27 3879
r9 0xbaf3fa0 196034464
r10 0x0 0
r11 0xf27 3879
r12 0x927db800 2457712640
r13 0x601082f0 1611694832
r14 0x1 1
r15 0x1 1
rip 0x8f96376 0x8f96376
eflags 0x246 [ PF ZF IF ]
cs 0x33 51
ss 0x2b 43
ds 0x0 0
es 0x0 0
fs 0x0 0
gs 0x0 0
st0 0 (raw 0x00000000000000000000)
---Type to continue, or q to quit---
st1 0 (raw 0x00000000000000000000)
st2 0 (raw 0x00000000000000000000)
st3 0 (raw 0x00000000000000000000)
st4 0 (raw 0x00000000000000000000)
st5 0 (raw 0x00000000000000000000)
st6 333296 (raw 0x4011a2be000000000000)
st7 300384 (raw 0x401192ac000000000000)
fctrl 0x27f 639
fstat 0x0 0
ftag 0xffff 65535
fiseg 0x0 0
fioff 0x9394e95 154750613
foseg 0x7fff 32767
fooff 0x1c573f50 475479888
fop 0x0 0
xmm0 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x0 }, v8_int16 = {0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, uint128 = 0x00000000000000000000000000000000}
xmm1 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x0 }, v8_int16 = {0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, uint128 = 0x00000000000000000000000000000000}
xmm2 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x0 }, v8_int16 = {0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, uint128 = 0x00000000000000000000000000000000}
xmm3 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x8000000000000000, 0x8000000000000000}, v16_int8 = {0xfe, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}, v8_int16 = {0xfffe, 0xffff, 0xffff, 0xffff, 0xfffe, 0xffff,
0xffff, 0xffff}, v4_int32 = {0xfffffffe, 0xffffffff, 0xfffffffe, 0xffffffff}, v2_int64 = {0xfffffffffffffffe, 0xfffffffffffffffe},
uint128 = 0xfffffffffffffffefffffffffffffffe}
---Type to continue, or q to quit---
xmm4 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x0 }, v8_int16 = {0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, uint128 = 0x00000000000000000000000000000000}
xmm5 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x32, 0xa3, 0xd7, 0x2, 0x0 },
v8_int16 = {0xa332, 0x2d7, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x2d7a332, 0x0, 0x0, 0x0}, v2_int64 = {0x2d7a332, 0x0},
uint128 = 0x00000000000000000000000002d7a332}
xmm6 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x0 }, v8_int16 = {0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, uint128 = 0x00000000000000000000000000000000}
xmm7 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0xda, 0x87, 0xd7, 0x2, 0x0 },
v8_int16 = {0x87da, 0x2d7, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x2d787da, 0x0, 0x0, 0x0}, v2_int64 = {0x2d787da, 0x0},
uint128 = 0x00000000000000000000000002d787da}
xmm8 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x0 }, v8_int16 = {0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, uint128 = 0x00000000000000000000000000000000}
xmm9 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x0 }, v8_int16 = {0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, uint128 = 0x00000000000000000000000000000000}
xmm10 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x0 }, v8_int16 = {0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, uint128 = 0x00000000000000000000000000000000}
xmm11 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x0 }, v8_int16 = {0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, uint128 = 0x00000000000000000000000000000000}
xmm12 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x18, 0xe, 0x73, 0x90, 0xb, 0x2b, 0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, v8_int16 = {0xe18, 0x9073, 0x2b0b, 0x0, 0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x90730e18, 0x2b0b, 0x0, 0x0},
v2_int64 = {0x2b0b90730e18, 0x0}, uint128 = 0x000000000000000000002b0b90730e18}
xmm13 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x0 }, v8_int16 = {0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, uint128 = 0x00000000000000000000000000000000}
xmm14 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x0 }, v8_int16 = {0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, uint128 = 0x00000000000000000000000000000000}
---Type to continue, or q to quit---
xmm15 {v4_float = {0x0, 0x0, 0x0, 0x0}, v2_double = {0x0, 0x0}, v16_int8 = {0x0 }, v8_int16 = {0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, v4_int32 = {0x0, 0x0, 0x0, 0x0}, v2_int64 = {0x0, 0x0}, uint128 = 0x00000000000000000000000000000000}
mxcsr 0x1fa1 [ IE PE IM DM ZM OM UM PM ]
(gdb)
7丶rdi/edi是第一个参数， rsi/esi是第二个参数，贴出info all-register命令所显示函数kslgetl ()的两个参数，如下
rsi 0x1 1 ----第二个参数
rdi 0x601082f0 1611694832 ----第一个参数
8丶找到第一个参数0x601082f0,注意因我的OS是64位，前面要补8个0，在v$latch_children视图中地址的字母要大写,
即0x601082f0要写为00000000601082F0
9丶通过视图v$latch_children找Latch锁（在第三个窗口执行）
sys@OCM> select name from v$latch_children where addr=\'00000000601082F0\';
NAME
----------------------------------------------------------------
shared pool
10丶发现Latch锁就是shared pool Latch。
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