Oracle诊断案例-Job任务停止执行[最终版]

Oracle诊断案例-Job任务停止执行

Last Updated: Friday, 2004-11-26 9:48 Eygle

昨天接到研发人员报告，数据库定时任务未正常执行，导致某些操作失败。

开始介入处理该事故.
系统环境:
SunOS DB 5.8 Generic_108528-21 sun4u sparc SUNW,Ultra-4
Oracle9i Enterprise Edition Release 9.2.0.3.0 - Production

1.首先介入检查数据库任务

$ sqlplus "/ as sysdba"SQL*Plus: Release 9.2.0.3.0 - Production on Wed Nov 17 20:23:53 2004Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.Connected to:Oracle9i Enterprise Edition Release 9.2.0.3.0 - ProductionWith the Partitioning, OLAP and Oracle Data Mining optionsJServer Release 9.2.0.3.0 - ProductionSQL> select job,last_date,last_sec,next_date,next_sec,broken,failures from dba_jobs; JOB LAST_DATE LAST_SEC NEXT_DATE NEXT_SEC B FAILURES INTERVAL---------- --------- ---------------- --------- ---------------- - ---------- ---------------------------- 31 16-NOV-04 01:00:02 17-NOV-04 01:00:00 N 0 trunc(sysdate+1)+1/24 27 16-NOV-04 00:00:04 17-NOV-04 00:00:00 N 0 TRUNC(SYSDATE) + 1 35 16-NOV-04 01:00:02 17-NOV-04 01:00:00 N 0 trunc(sysdate+1)+1/24 29 16-NOV-04 00:00:04 17-NOV-04 00:00:00 N 0 TRUNC(SYSDATE) + 1 30 01-NOV-04 06:00:01 01-DEC-04 06:00:00 N 0 trunc(add_months(sysdate,1),'MM')+6/24 65 16-NOV-04 04:00:03 17-NOV-04 04:00:00 N 0 trunc(sysdate+1)+4/24 46 16-NOV-04 02:14:27 17-NOV-04 02:14:27 N 0 sysdate+1 66 16-NOV-04 03:00:02 17-NOV-04 18:14:49 N 0 trunc(sysdate+1)+3/248 rows selected.

发现JOB任务是都没有正常执行，最早一个应该在17-NOV-04 01:00:00执行。但是没有执行。

2.建立测试JOB

create or replace PROCEDURE pining ISBEGIN NULL; END;/variable jobno number;variable instno number;begin select instance_number into :instno from v$instance; dbms_job.submit(:jobno, 'pining;', trunc(sysdate+1/288,'MI'), 'trunc(SYSDATE+1/288,''MI'')', TRUE, :instno);end;/

发现同样的，不执行。
但是通过dbms_job.run(

  1<job>)执行没有任何问题。   
  2  
  33.进行恢复尝试   
  4  
  5怀疑是CJQ0进程失效，首先设置JOB_QUEUE_PROCESSES为0，Oracle会杀掉CJQ0及相应job进程   
  6SQL&gt; ALTER SYSTEM SET JOB_QUEUE_PROCESSES = 0;   
  7  
  8等2~3分钟，重新设置   
  9  
 10SQL&gt; ALTER SYSTEM SET JOB_QUEUE_PROCESSES = 5;   
 11  
 12此时PMON会重起CJQ0进程   
 13  
 14在警报日志中可以看到以下信息:   
 15  
 16  
 17  
 18Thu Nov 18 11:59:50 2004ALTER SYSTEM SET job_queue_processes=0 SCOPE=MEMORY;Thu Nov 18 12:01:30 2004ALTER SYSTEM SET job_queue_processes=10 SCOPE=MEMORY;Thu Nov 18 12:01:30 2004Restarting dead background process CJQ0CJQ0 started with pid=8   
 19  
 20  
 21  
 22但是Job仍然不执行，而且在再次修改的时候，CJQ0直接死掉了。   
 23  
 24  
 25  
 26Thu Nov 18 13:52:05 2004ALTER SYSTEM SET job_queue_processes=0 SCOPE=MEMORY;Thu Nov 18 14:09:30 2004ALTER SYSTEM SET job_queue_processes=10 SCOPE=MEMORY;Thu Nov 18 14:10:27 2004ALTER SYSTEM SET job_queue_processes=0 SCOPE=MEMORY;Thu Nov 18 14:10:42 2004ALTER SYSTEM SET job_queue_processes=10 SCOPE=MEMORY;Thu Nov 18 14:31:07 2004ALTER SYSTEM SET job_queue_processes=0 SCOPE=MEMORY;Thu Nov 18 14:40:14 2004ALTER SYSTEM SET job_queue_processes=10 SCOPE=MEMORY;Thu Nov 18 14:40:28 2004ALTER SYSTEM SET job_queue_processes=0 SCOPE=MEMORY;Thu Nov 18 14:40:33 2004ALTER SYSTEM SET job_queue_processes=1 SCOPE=MEMORY;Thu Nov 18 14:40:40 2004ALTER SYSTEM SET job_queue_processes=10 SCOPE=MEMORY;Thu Nov 18 15:00:42 2004ALTER SYSTEM SET job_queue_processes=0 SCOPE=MEMORY;Thu Nov 18 15:01:36 2004ALTER SYSTEM SET job_queue_processes=15 SCOPE=MEMORY;   
 27  
 284.尝试重起数据库   
 29这个必须在晚上进行   
 30  
 31  
 32  
 33PMON started with pid=2DBW0 started with pid=3LGWR started with pid=4CKPT started with pid=5SMON started with pid=6RECO started with pid=7CJQ0 started with pid=8QMN0 started with pid=9....   
 34  
 35CJQ0正常启动，但是Job仍然不执行。   
 36  
 375.没办法了...   
 38  
 39继续研究...居然发现Oralce有这样一个bug   
 40  
 411\. Clear description of the problem encountered:   
 42slgcsf() / slgcs() on Solaris will stop incrementing after   
 43497 days 2 hrs 28 mins (approx) machine uptime.   
 44  
 45  
 462\. Pertinent configuration information   
 47No special configuration other than long machine uptime. .   
 48  
 493\. Indication of the frequency and predictability of the problem   
 50100% but only after 497 days.   
 51  
 524\. Sequence of events leading to the problem   
 53If the gethrtime() OS call returns a value &gt; 42949672950000000   
 54nanoseconds then slgcs() stays at 0xffffffff. This can   
 55cause some problems in parts of the code which rely on   
 56slgcs() to keep moving.   
 57eg: In kkjssrh() does "now = slgcs(&amp;se)" and compares that   
 58to a previous timestamp. After 497 days uptime slgcs()   
 59keeps returning 0xffffffff so "now - kkjlsrt" will   
 60always return 0. .   
 61  
 625\. Technical impact on the customer. Include persistent after effects.   
 63In this case DBMS JOBS stopped running after 497 days uptime.   
 64Other symptoms could occur in various places in the code.   
 65  
 66好么，原来是计时器溢出了，一检查我的主机:   
 67  
 68bash-2.03$ uptime 10:00pm up 500 day(s), 14:57, 1 user, load average: 1.31, 1.09, 1.08bash-2.03$ dateFri Nov 19 22:00:14 CST 2004   
 69  
 70  
 71  
 72刚好到事发时是497天多一点.ft.   
 73  
 746.安排重起主机系统..   
 75  
 76这个问题够郁闷的，NND，谁曾想Oracle这都成...   
 77  
 78Oracle最后声称:   
 79  
 80fix made it into 9.2.0.6 patchset   
 81  
 82在Solaris上的9206尚未发布...晕.   
 83  
 84好了，就当是个经历吧，如果有问题非常不可思议的话，那么大胆怀疑Oracle吧，是Bug，可能就是Bug。   
 85  
 86重起以后问题解决，状态如下:   
 87  
 88$ sqlplus "/ as sysdba"SQL*Plus: Release 9.2.0.3.0 - Production on Fri Nov 26 09:21:21 2004Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.Connected to:Oracle9i Enterprise Edition Release 9.2.0.3.0 - ProductionWith the Partitioning, OLAP and Oracle Data Mining optionsJServer Release 9.2.0.3.0 - ProductionSQL&gt; select job,last_date,last_sec,next_date,next_sec from user_jobs; JOB LAST_DATE LAST_SEC NEXT_DATE NEXT_SEC---------- --------- ---------------- --------- ---------------- 70 26-NOV-04 09:21:04 26-NOV-04 09:26:00SQL&gt; / JOB LAST_DATE LAST_SEC NEXT_DATE NEXT_SEC---------- --------- ---------------- --------- ---------------- 70 26-NOV-04 09:26:01 26-NOV-04 09:31:00SQL&gt; SQL&gt; select * from v$timer; HSECS---------- 3388153SQL&gt; select * from v$timer; HSECS---------- 3388319SQL&gt;   
 89  
 90  
 91  
 927.FAQ   
 93  
 94一些朋友在Pub上问的问题   
 95Q:对于不同平台，是否存在同样的问题?   
 96  
 97A:对于不同平台，存在同样的问题   
 98因为Oracle使用了标准C函数gethrtime   
 99参考:   
100http://www.eygle.com/unix/Man.Page.Of.gethrtime.htm   
101  
102使用了该函数的代码都会存在问题.   
103  
104在Metalink Note:3427424.8 文档中，Oracle定义的平台影响为:Generic (all / most platforms affected)   
105  
106Q.计数器溢出，看了看job 中基本都是1天左右执行一次，如果设置 3 天执行一次的 job , 是否出问题的uptime 应该是 497*3 之后呢 ？   
107  
108A:不会   
109  
110Oracle内部通过计时器来增进相对时间.   
111由于Oracle内部hrtime_t使用了32位计数   
112  
113那么最大值也就是0xffffffff   
1140xffffffff = 4294967295   
115  
116slgcs()是10亿分之一秒，溢出在42949672950000000这个点上.   
117  
118注意，这里0xffffffff，达到这个值时，本来是无符号整型，现在变成了-1，那么这个值递增时，+1 = 0了。   
119时间就此停住了。   
120  
121我写了一小段代码来验证这个内容，参考：   
122  
123[oracle@jumper oracle]$ cat unsign.c#include int main(void){unsigned int num = 0xffffffff;printf("num is %d bits long\n", sizeof(num) * 8);printf("num = 0x%x\n", num);printf("num + 1 = 0x%x\n", num + 1);return 0;}[oracle@jumper oracle]$ gcc -o unsign.sh unsign.c[oracle@jumper oracle]$ ./unsign.shnum is 32 bits longnum = 0xffffffffnum + 1 = 0x0[oracle@jumper oracle]$   
124  
125  
126  
127  
128Q:内部时钟之一应该就是这个吧： v$timer 精确到1/100 秒的数据   
129  
130没错!   
131  
132注意前面说的:   
133  
1344\. Sequence of events leading to the problem   
135If the gethrtime() OS call returns a value &gt; 42949672950000000   
136nanoseconds then slgcs() stays at 0xffffffff. This can   
137cause some problems in parts of the code which rely on   
138slgcs() to keep moving.   
139  
140也就是说如果gethrtime() 操作系统调用返回值大于42949672950000000（单位10亿分之一秒）   
141  
142也就是说Oracle将得到一个cs值为4294967295的时间值   
143  
144而4294967295值就是0xffffffff   
145  
146所以当时v$timer的计时也就是:   
147  
148SQL&gt; select * from v$timer; HSECS----------4294967295SQL&gt; / HSECS----------4294967295SQL&gt; / HSECS----------4294967295SQL&gt;   
149  
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155  
156本文作者:   
157eygle,Oracle技术关注者,来自中国最大的Oracle技术论坛itpub.   
158www.eygle.com是作者的个人站点.你可通过[email protected]来联系作者.欢迎技术探讨交流以及链接交换.   
159  
160原文出处:   
161  
162http://www.eygle.com/case/Job.Can.Not.Execute.Auto.htm</job>