Oracle Hang分析--转载

时间 2019-11-06

原文原文链接

1. 数据库hang的几种可能性node

oracle 死锁或者系统负载很是高好比cpu使用或其余一些锁等待很高均可能致使系统hang住，好比大量的DX锁。sql

一般来讲，咱们所指的系统hang住，是指应用无响应，普通的sqlplus几乎没法操做等等。数据库

2. 如何进行hang分析？hang分析有哪些level？如何选择level？bash

hanganalyze有以下几种level：session

10     Dump all processes (IGN state)
5      Level 4 + Dump all processes involved in wait chains (NLEAF state)
4      Level 3 + Dump leaf nodes (blockers) in wait chains (LEAF,LEAF_NW,IGN_DMP state)
3      Level 2 + Dump only processes thought to be in a hang (IN_HANG state)
1-2    Only HANGANALYZE output, no process dump at alloracle

如何选择level？this

通常来讲，不建议使用3以上级别的hang分析，由于可能会产生很是大的trace，还可能对系统的IO有必定影响。spa

从oracle 9i开始 hanganalyze提供给了对rac的支持。.net

有以下2种方式：debug

1) ALTER SESSION SET EVENTS 'immediate trace name HANGANALYZE level ';

2) 使用oradebug 命令

   ORADEBUG setmypid
   ORADEBUG setinst all
   ORADEBUG -g def hanganalyze        ---针对rac的用法

oradebug setmypid
oradebug hanganalyze 3 ---非rac环境

一般在作hang分析的时候，oracle建议同时作一个systemstate的dump

oradebug SYSTEMSTATE dump level 2     level 2便可，包含了全部session的信息。
      sqlplus -prelim / as sysdba       ---10g能够使用此方式登陆
      oradebug setospid
      oradebug unlimit
      oradebug dump systemstate 10
补充：有时候咱们可能还须要对某个进程进行trace aix环境，咱们能够使用dbx命令
以下例子：

dbx -a PID (where PID = any oracle shadow process) ---经过ps -ef|grep xxx查看
dbx() print ksudss(10)
dbx() detach

3. 如何解读hang分析的trace文件，获取有用信息?

*** ACTION NAME:() 2010-03-12 00:04:01.497
*** MODULE NAME:(sqlplus@S7_C_YZ_YZSJK (TNS V1-V3)) 2010-03-12 00:04:01.497    ---模块名跟v$session.module_name同样
*** SERVICE NAME:(SYS$USERS) 2010-03-12 00:04:01.497
*** SESSION ID:(5184.45287) 2010-03-12 00:04:01.497         ----sid (5184)   serial# (35287)
*** 2010-03-12 00:04:01.497
==============
HANG ANALYSIS:
==============
Found 54 objects waiting for
    <0/5210/10419/0x99d0a88/11215038/No Wait>                          ------从这里看 session 5210 阻塞了54个对象
Open chains found:
Chain 1 : :        ---从这里开始如下的session都是被前面的5210阻塞一般来讲是一个阻塞另外一个
    <0/5210/10419/0x99d0a88/11215038/No Wait>
-- <0/3994/15494/0xd9ac1b0/6574102/enq: TM - contention>
-- <0/4962/58962/0xca03618/5710044/enq: DX - contention>
Other chains found:                                                ---下面的session也是被前面所阻塞不过不是直接阻塞（by Open chains）间接阻塞
Chain 2 : :
    <0/4001/31548/0xf9f3ab0/4980956/enq: DX - contention>
Chain 3 : :
    <0/4014/30717/0xaa27b48/7446746/gc buffer busy>
Chain 4 : :
    <0/4039/42115/0xd9f5710/5595180/PX Deq: Table Q Normal>

Cycle 1 : : ---cycle 一般是死锁通常来讲颇有可能就是hang的根源
<980/3887/0xe4214964/24065/latch free>
-- <2518/352/0xe4216560/24574/latch free>
-- <55/10/0xe41236a8/13751/latch free>

4. 不一样版本hang分析的差别？trace有何异同？

以下是oracle8~10g的 hanganalyze trace信息格式：

Oracle 8.x : [nodenum]/sid/sess_srno/session/state/start/finish/[adjlist]/predecessor
Oracle9i: [nodenum]/cnode/sid/sess_srno/session/ospid/state/start/finish/[adjlist]/predecessor
Oracle10g：[nodenum]/cnode/sid/sess_srno/session/ospid/state/start/finish/[adjlist]/predecessor
Nodenum     --》每一个session作hanganalyze生成的一个序列号
sid         --》 Session ID
sess_srno   --》 Serial#
ospid       --》 OS Process Id (v$process spid)
state       --》 State of the node
adjlist     --》 adjacent node   (Usually represents a blocker node) --一般是阻塞者
predecessor --》 predecessor node (Usually represents a waiter node) --一般是被阻塞者
cnode       --》节点号从9i开始才有

关于state 有以下几种值:

IN_HANG --》该状态是一个很是危险的状态，一般表现为一个节点陷入了死循环或是hung。通常来讲出现这种状况，该节点的临辟节点也是同样的状态即adjlist

            以下例子：
            [16]/0/17/154/0x24617be0/26800/IN_HANG/29/32/[185]/19      ---从IN_HANG 咱们能够看出 185是16的邻居节点，185被16阻塞
            [185]/1/16/4966/0x24617270//IN_HANG/30/31/[16]/16          ---从这里看 185阻塞了16（16是waiter）

LEAF --》一般是被认为blockers的重点对象。那么如何去肯定呢？通常来讲，根据后面的predecesor来判断该session是否是blocker或者是waiter。

             以下例子：
             [ nodenum]/cnode/sid/sess_srno/session/ospid/state/start/finish/[adjlist]/predecessor
             [16]/0/17/154/0x24617be0/26800/LEAF/29/30//19         --从这里看19是waiter 所以咱们认为17阻塞了20
             [19]/0/20/13/0x24619830/26791/NLEAF/33/34/[16]/186

LEAF_NW     --》跟leaf相似不过可能会占用cpu
NLEAF       --》该状态的session一般被认为 “stuck” session。即其余session所须要的资源正被其holding。
IGN         --》该状态的session一般是处理IDLE状态，除非其adjlist存在，若是是，那么该session正在等待其余session。
IGN_DMP     --》跟 IGN 相似。

以下例子：

[nodenum]/cnode/sid/sess_srno/session/ospid/state/start/finish/[adjlist]/predecessor
[16]/0/17/154/0x24617be0/26800/LEAF/29/30//19
[19]/0/20/13/0x24619830/26791/NLEAF/33/34/[16]/186
[189]/1/20/36/0x24619830//IGN/95/96/[19]/none
[176]/1/7/1/0x24611d80//IGN/75/76//none

----从上面看，189在等待19,19在等待16，而176是一个idle session。

SINGLE_NODE，SINGLE_NODE_NW 能够认为跟LEAF，LEAF_NW同样，除非没有依赖对象。

本节我基于scott用户产生两个会话，模拟死锁会话(一个update,一个delete)

SQL> oradebug help
HELP           [command]                 Describe one or all commands
SETMYPID                                 Debug current process
SETOSPID                          Set OS pid of process to debug
SETORAPID      ['force']        Set Oracle pid of process to debug
SHORT_STACK                              Dump abridged OS stack
DUMP           <dump_name>[addr] Invoke named dump
DUMPSGA        [bytes]                   Dump fixed SGA
DUMPLIST                                 Print a list of available dumps
EVENT                              Set trace event in process
SESSION_EVENT                      Set trace event in session
DUMPVAR        <p|s|uga>[level] Print/dump a fixed PGA/SGA/UGA variable
DUMPTYPE

Print/dump an address with type info
SETVAR         <p|s|uga> Modify a fixed PGA/SGA/UGA variable
PEEK           [level]      Print/Dump memory
POKE                 Modify memory
WAKEUP                           Wake up Oracle process
SUSPEND                                  Suspend execution
RESUME                                   Resume execution
FLUSH                                    Flush pending writes to trace file
CLOSE_TRACE                              Close trace file
TRACEFILE_NAME                           Get name of trace file
LKDEBUG                                  Invoke global enqueue service debugger
NSDBX                                    Invoke CGS name-service debugger
-G                Parallel oradebug command prefix
-R                Parallel oradebug prefix (return output
SETINST        <instance# ..="" |="" all="">      Set instance list in double quotes
SGATOFILE               Dump SGA to file; dirname in double quotes
DMPCOWSGA      Dump & map SGA as COW; dirname in double quotes
MAPCOWSGA               Map SGA as COW; dirname in double quotes
HANGANALYZE    [level] [syslevel]        Analyze system hang
FFBEGIN                                  Flash Freeze the Instance
FFDEREGISTER                             FF deregister instance from cluster
FFTERMINST                               Call exit and terminate instance
FFRESUMEINST                             Resume the flash frozen instance
FFSTATUS                                 Flash freeze status of instance
SKDSTTPCS                Helps translate PCs to names
WATCH

<self|exist|all|target> Watch a region of memory
DELETE         <local|global|target>watchpoint     Delete a watchpoint
SHOW           <local|global|target>watchpoints        Show watchpoints
CORE                                     Dump core without crashing process
IPC                                      Dump ipc information
UNLIMIT                                  Unlimit the size of the trace file
PROCSTAT                                 Dump process statistics
CALL           [arg1] ... [argn] Invoke function with arguments

SQL> oradebug hanganalyze 3;
Hang Analysis in /oracle/admin/orcl/udump/orcl_ora_2622.trc
SQL> exit
Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
-bash-3.2$ more /oracle/admin/orcl/udump/orcl_ora_2622.trc
/oracle/admin/orcl/udump/orcl_ora_2622.trc
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
ORACLE_HOME = /oracle/product/10.2.0/db_1
System name:    Linux
Node name:      truerhel5
Release:        2.6.18-164.el5
Version:        #1 SMP Tue Aug 18 15:51:48 EDT 2009
Machine:        x86_64
Instance name: orcl
Redo thread mounted by this instance: 1
Oracle process number: 21
Unix process pid: 2622, image:oracle@truerhel5(TNS V1-V3)

*** SERVICE NAME:(SYS$USERS) 2010-08-07 21:11:10.818
*** SESSION ID:(145.36) 2010-08-07 21:11:10.818
*** 2010-08-07 21:11:10.818
==============
HANG ANALYSIS:
==============
Open chains found:
Chain 1 : : --每列的注解：分为cnode sid sess_srno proc_ptr ospid wait_event
    <0/148/27/0x70e5e4a8/2543/SQL*Net message from client>   --会话148(持锁会话）
-- <0/146/84/0x70e5f478/2607/enq: TX - row lock contention> --会话146(等待锁会话），竞争事件为：row lock contention
Other chains found:
Chain 2 : :
    <0/144/108/0x70e5ccf0/2614/jobq slave wait>
Chain 3 : :
    <0/145/36/0x70e5fc60/2622/No Wait>
Chain 4 : :
    <0/150/2/0x70e623e8/2338/Streams AQ: waiting for time man>
Chain 5 : :
    <0/151/1/0x70e5ec90/2319/Streams AQ: qmn coordinator idle>
Chain 6 : :
    <0/158/7/0x70e61c00/2336/Streams AQ: qmn slave idle wait>
Extra information that will be dumped at higher levels:
[level 4] :   1 node dumps -- [REMOTE_WT] [LEAF] [LEAF_NW]
[level 5] :   5 node dumps -- [SINGLE_NODE] [SINGLE_NODE_NW] [IGN_DMP]
[level 6] :   1 node dumps -- [NLEAF]
[level 10] : 13 node dumps -- [IGN]

State of nodes
([nodenum]/cnode/sid/sess_srno/session/ospid/state/start/finish/[adjlist]/predecessor):
[143]/0/144/108/0x70f5dcf8/2614/SINGLE_NODE/1/2//none
[144]/0/145/36/0x70f5f130/2622/SINGLE_NODE_NW/3/4//none
[145]/0/146/84/0x70f60568/2607/NLEAF/5/8/[147]/none
[147]/0/148/27/0x70f62dd8/2543/LEAF/6/7//145
[149]/0/150/2/0x70f65648/2338/SINGLE_NODE/9/10//none
[150]/0/151/1/0x70f66a80/2319/SINGLE_NODE/11/12//none
[154]/0/155/1/0x70f6bb60/2315/IGN/13/14//none
[155]/0/156/1/0x70f6cf98/2313/IGN/15/16//none
[157]/0/158/7/0x70f6f808/2336/SINGLE_NODE/17/18//none
[159]/0/160/1/0x70f72078/2305/IGN/19/20//none
[160]/0/161/1/0x70f734b0/2303/IGN/21/22//none
[161]/0/162/1/0x70f748e8/2301/IGN/23/24//none
[162]/0/163/1/0x70f75d20/2299/IGN/25/26//none
[163]/0/164/1/0x70f77158/2297/IGN/27/28//none
[164]/0/165/1/0x70f78590/2295/IGN/29/30//none
[165]/0/166/1/0x70f799c8/2293/IGN/31/32//none
[166]/0/167/1/0x70f7ae00/2291/IGN/33/34//none
[167]/0/168/1/0x70f7c238/2289/IGN/35/36//none
[168]/0/169/1/0x70f7d670/2287/IGN/37/38//none
[169]/0/170/1/0x70f7eaa8/2285/IGN/39/40//none
====================
END OF HANG ANALYSIS
====================

其内容意思大概以下

cnode--节点代号,若是为rac,其值就存在,单节点的值为0

sid---session的sid

sess_srno---session的serial#

proc_ptr--系统进程指向的address

ospid ----进程号

wait_event---session的等待事件

转摘白大师部分节选
Hanganalyze是从Oracle 8i r2(8.1.6)开始提供的，其用法十分简单：

ALTER SESSION SET EVENTS 'immediate trace name HANGANALYZE level ';

或者

ORADEBUG hanganalyze

好比：

sql>oradebug setmypid;

sql>oradebug hanganalyze 3;

对于：

      10     Dump all processes (IGN state)
      5      Level 4 + Dump all processes involved in wait chains (NLEAF state)
      4      Level 3 + Dump leaf nodes (blockers) in wait chains (LEAF,LEAF_NW,IGN_DMP state)
      3      Level 2 + Dump only processes thought to be in a hang (IN_HANG state)
    1-2    Only HANGANALYZE output, no process dump at all

-bash-3.2$ sqlplus -prelim '/as sysdba' --经过prelim选项进入已经hang住（正常方式进不了sqlplus)的数据库

SQL*Plus: Release 10.2.0.1.0 - Production on Sat Aug 7 21:17:42 2010

SQL> show parameter sga
ORA-01012: not logged on

SQL> conn /as sysdbaPrelim connection establishedSQL>

http://blog.itpub.net/16978544/viewspace-701657/