如果Oracle数据库hang了，对Oracle进行system dump或hang analyze，是研究和解决问题的有效方法。如果能够连接数据库，并进行操作，则使用oradebug是最简单快捷的办法。
但有的时候，数据库由于hang住，sqlplus不能连接时(在10g可以尝试用sqlplus -prelim连接数据库），可以使用操作系统上的调试工具来dump oracle系统状态。因为我的环境是linux，所以我先从gdb来介绍。
①首先获得要dump的进程号
ps -ef | grep LOCAL
oracle 9015 1 0 12:28 ? 00:00:00 oracleretest (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq)))
oracle 9110 8981 0 14:09 pts/4 00:00:00 grep LOCAL
②调用gdb进行dump
gdb $ORACLE_HOME/bin/oracle 9015
GNU gdb Red Hat Linux (6.1post-1.20040607.62rh)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type “show copying” to see the conditions.
There is absolutely no warranty for GDB. Type “show warranty” for details.
This GDB was configured as “i386-RedHat-linux-gnu”…(no debugging symbols found)…Using host libthread_db library “/lib/tls/libthread_db.so.1″.
Attaching to program: /u01/app/oracle/product/10.1.0/db_1/bin/oracle, process 9015
Reading symbols from /u01/app/oracle/product/10.1.0/db_1/lib/libskgxp10.so…(no debugging symbols found)…done.
Loaded symbols for /u01/app/oracle/product/10.1.0/db_1/lib/libskgxp10.so
Reading symbols from /u01/app/oracle/product/10.1.0/db_1/lib/libhasgen10.so…done.
Loaded symbols for /u01/app/oracle/product/10.1.0/db_1/lib/libhasgen10.so
Reading symbols from /u01/app/oracle/product/10.1.0/db_1/lib/libskgxn2.so…done.
Loaded symbols for /u01/app/oracle/product/10.1.0/db_1/lib/libskgxn2.so
Reading symbols from /u01/app/oracle/product/10.1.0/db_1/lib/libocr10.so…done.
Loaded symbols for /u01/app/oracle/product/10.1.0/db_1/lib/libocr10.so
Reading symbols from /u01/app/oracle/product/10.1.0/db_1/lib/libocrb10.so…done.
Loaded symbols for /u01/app/oracle/product/10.1.0/db_1/lib/libocrb10.so
Reading symbols from /u01/app/oracle/product/10.1.0/db_1/lib/libocrutl10.so…done.
Loaded symbols for /u01/app/oracle/product/10.1.0/db_1/lib/libocrutl10.so
Reading symbols from /u01/app/oracle/product/10.1.0/db_1/lib/libjox10.so…done.
Loaded symbols for /u01/app/oracle/product/10.1.0/db_1/lib/libjox10.so
Reading symbols from /u01/app/oracle/product/10.1.0/db_1/lib/libclsra10.so…done.
Loaded symbols for /u01/app/oracle/product/10.1.0/db_1/lib/libclsra10.so
Reading symbols from /u01/app/oracle/product/10.1.0/db_1/lib/libdbcfg10.so…done.
Loaded symbols for /u01/app/oracle/product/10.1.0/db_1/lib/libdbcfg10.so
Reading symbols from /u01/app/oracle/product/10.1.0/db_1/lib/libnnz10.so…done.
Loaded symbols for /u01/app/oracle/product/10.1.0/db_1/lib/libnnz10.so
Reading symbols from /usr/lib/libaio.so.1…done.
Loaded symbols for /usr/lib/libaio.so.1
Reading symbols from /lib/libdl.so.2…done.
Loaded symbols for /lib/libdl.so.2
Reading symbols from /lib/tls/libm.so.6…done.
Loaded symbols for /lib/tls/libm.so.6
Reading symbols from /lib/tls/libpthread.so.0…done.
[Thread debugging using libthread_db enabled]
[New Thread -1219938624 (LWP 3765)]
Loaded symbols for /lib/tls/libpthread.so.0
Reading symbols from /lib/libnsl.so.1…done.
Loaded symbols for /lib/libnsl.so.1
Reading symbols from /lib/tls/libc.so.6…done.
Loaded symbols for /lib/tls/libc.so.6
Reading symbols from /lib/ld-linux.so.2…done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /lib/libnss_files.so.2…done.
Loaded symbols for /lib/libnss_files.so.2
0×006967a2 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
(gdb) print ksudss(10)
[Switching to Thread -1219938624 (LWP 9015)]
$1 = 213658428
(gdb) detach
Detaching from program: /u01/app/oracle/product/10.1.0/db_1/bin/oracle, process 9015
(gdb) quit