Troubleshooting Connected to an idle instance, But Instance is running

前几日有朋友遇到了这个问题，实例是启动的，但是经常过一段时间连接数据库实例时提示"Connected to an idle instance"，环境：RAC oracle 11.2.0.4.0 操作系统RHEL 6.5。

[oracle@anbob1 trace]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Wed Sep 19 20:27:51 2018
Copyright (c) 1982, 2013, Oracle.  All rights reserved.
Connected to an idle instance.
Errors in file /s01/oracle/app/oracle/diag/rdbms/anbob/ANBOB1/trace/ANBOB1_cjq0_14004.trc:
Process J000 died, see its trace file
kkjcre1p: unable to spawn jobq slave process
Errors in file /s01/oracle/app/oracle/diag/rdbms/anbob/ANBOB1/trace/ANBOB1_cjq0_14004.trc:
Process J000 died, see its trace file

Trace file SHOW

*** 2018-09-19 19:10:02.211
Process J000 is dead (pid=6055 req_ver=46668 cur_ver=46668 state=KSOSP_SPAWNED).
*** 2018-09-19 19:10:04.216
Process J000 is dead (pid=6060 req_ver=46669 cur_ver=46669 state=KSOSP_SPAWNED).
*** 2018-09-19 19:10:06.220
Process J000 is dead (pid=6068 req_ver=46670 cur_ver=46670 state=KSOSP_SPAWNED).
*** 2018-09-19 19:10:08.214
Process J000 is dead (pid=6079 req_ver=46671 cur_ver=46671 state=KSOSP_SPAWNED).
...

分析需要的数据：

$ env|grep ORA
$ ps -ef|grep smon
$ cat /etc/sysctl.conf
$ ulimit -a
$ cat /etc/security/limits.conf
$ cat /proc/meminfo 
$ ipcs -m
$ sysresv
$ df 
# or truss 
$ strace -a -e -f -tt -o connect.out sqlplus "/as sysdba"
从pfile或正常时的参数信息
SQL> show parameter mem
SQL> show parameter ga
SQL> show parameter job
SQL> select * from gv$resource_limit

可能的原因:
1. OS资源限制
2. Memory 或SWAP 不足
3. Memory_target Enabled
4. job_queue_processes参数不合理
5. Oracle Bugs. e.g. 24921392
如果您解决不了，可以联系我们。