本文通过一次Oracle Job任务异常案例诊断，分析其原因及解决过程，从内部揭示Oracle Job任务调度及内部计时机制。
问题及环境
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 |
解决过程
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 2004 Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved. Connected to: Oracle9i Enterprise Edition Release 9.2.0.3.0 - Production With the Partitioning, OLAP and Oracle Data Mining options JServer Release 9.2.0.3.0 - Production SQL> 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)+3/24 8 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。
建立测试JOB
| create or replace PROCEDURE pining IS BEGIN 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(<job>)执行没有任何问题。
进行恢复尝试
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
| SQL> ALTER SYSTEM SET JOB_QUEUE_PROCESSES = 0; |
等2~3分钟，重新设置
| SQL> ALTER SYSTEM SET JOB_QUEUE_PROCESSES = 5; |
此时PMON会重起CJQ0进程
| Thu Nov 18 11:59:50 2004 ALTER SYSTEM SET job_queue_processes=0 SCOPE=MEMORY; Thu Nov 18 12:01:30 2004 ALTER SYSTEM SET job_queue_processes=10 SCOPE=MEMORY; Thu Nov 18 12:01:30 2004 Restarting dead background process CJQ0 CJQ0 started with pid=8 但是Job仍然不执行，而且在再次修改的时候，CJQ0直接死掉了。 Thu Nov 18 13:52:05 2004 ALTER SYSTEM SET job_queue_processes=0 SCOPE=MEMORY; Thu Nov 18 14:09:30 2004 ALTER SYSTEM SET job_queue_processes=10 SCOPE=MEMORY; Thu Nov 18 14:10:27 2004 ALTER SYSTEM SET job_queue_processes=0 SCOPE=MEMORY; Thu Nov 18 14:10:42 2004 ALTER SYSTEM SET job_queue_processes=10 SCOPE=MEMORY; Thu Nov 18 14:31:07 2004 ALTER SYSTEM SET job_queue_processes=0 SCOPE=MEMORY; Thu Nov 18 14:40:14 2004 ALTER SYSTEM SET job_queue_processes=10 SCOPE=MEMORY; Thu Nov 18 14:40:28 2004 ALTER SYSTEM SET job_queue_processes=0 SCOPE=MEMORY; Thu Nov 18 14:40:33 2004 ALTER SYSTEM SET job_queue_processes=1 SCOPE=MEMORY; Thu Nov 18 14:40:40 2004 ALTER SYSTEM SET job_queue_processes=10 SCOPE=MEMORY; Thu Nov 18 15:00:42 2004 ALTER SYSTEM SET job_queue_processes=0 SCOPE=MEMORY; Thu Nov 18 15:01:36 2004 ALTER SYSTEM SET job_queue_processes=15 SCOPE=MEMORY; |
尝试重起数据库，这个必须在晚上进行：
| PMON started with pid=2 DBW0 started with pid=3 LGWR started with pid=4 CKPT started with pid=5 SMON started with pid=6 RECO started with pid=7 CJQ0 started with pid=8 QMN0 started with pid=9 .... |
CJQ0正常启动，但是Job仍然不执行。
没办法了...
继续研究...居然发现Oralce有这样一个bug
| 1. Clear description of the problem encountered: slgcsf() / slgcs() on Solaris will stop incrementing after 497 days 2 hrs 28 mins (approx) machine uptime. 2. Pertinent configuration information No special configuration other than long machine uptime. . 3. Indication of the frequency and predictability of the problem 100% but only after 497 days. 4. Sequence of events leading to the problem If the gethrtime() OS call returns a value > 42949672950000000 nanoseconds then slgcs() stays at 0xffffffff. This can cause some problems in parts of the code which rely on slgcs() to keep moving. eg: In kkjssrh() does "now = slgcs(&se)" and compares that to a previous timestamp. After 497 days uptime slgcs() keeps returning 0xffffffff so "now - kkjlsrt" will always return 0. . 5. Technical impact on the customer. Include persistent after effects. In this case DBMS JOBS stopped running after 497 days uptime. Other symptoms could occur in various places in the code. |
好么，原来是计时器溢出了，一检查我的主机:
| bash-2.03$ uptime 10:00pm up 500 day(s), 14:57, 1 user, load average: 1.31, 1.09, 1.08 bash-2.03$ date Fri Nov 19 22:00:14 CST 2004 |
刚好到事发时是497天多一点.ft.
安排重起主机系统..
这个问题够郁闷的，NND，谁曾想Oracle这都成...
Oracle最后声称:
fix made it into 9.2.0.6 patchset
在Solaris上的9206尚未发布...晕.
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。
重起以后问题解决，状态如下:
| $ sqlplus "/ as sysdba" SQL*Plus: Release 9.2.0.3.0 - Production on Fri Nov 26 09:21:21 2004 Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved. Connected to: Oracle9i Enterprise Edition Release 9.2.0.3.0 - Production With the Partitioning, OLAP and Oracle Data Mining options JServer Release 9.2.0.3.0 - Production SQL> 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 09:26:00 SQL> / JOB LAST_DATE LAST_SEC NEXT_DATE NEXT_SEC ---------- --------- ---------------- --------- ---------------- 70 26-NOV-04 09:26:01 26-NOV-04 09:31:00 SQL> SQL> select * from v$timer; HSECS ---------- 3388153 SQL> select * from v$timer; HSECS ---------- 3388319 SQL> FAQ |
