ORA-12537: TNS:connection closed错误处理过程

1，同事说Oracle测试换了连接不上了，报错如下

[oracle@pldb236 admin]$ rlwrap sqlplus powerdesk/pd141118@PD236

SQL*Plus: Release 11.2.0.1.0 Production on Mon Nov 23 14:16:31 2015

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

ERROR:
ORA-12537: TNS:connection closed


Enter user-name:

检查监听正常，Oracle服务也是正常启动的，但是登录不进去

[oracle@pldb236 admin]$ tnsping PD236

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 23-NOV-2015 14:17:22

Copyright (c) 1997, 2009, Oracle.  All rights reserved.

Used parameter files:


Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.180.236)(PORT = 1521))) (CONNECT_DATA = (SERVICE_NAME = powerdes)))
OK (10 msec)
[oracle@pldb236 admin]$

2，解决方案

[oracle@pldb236 bin]$ cd $ORACLE_HOME/bin/
[oracle@pldb236 bin]$ 
[oracle@pldb236 bin]$ 
[oracle@pldb236 bin]$ ll oracle
-rwsr-s--x. 1 oracle oinstall 210823844 Jul 31 13:21 oracle
[oracle@pldb236 bin]$ 
[oracle@pldb236 bin]$ chmod 6571 oracle
[oracle@pldb236 bin]$ 
[oracle@pldb236 bin]$ ll oracle
-r-srws--x. 1 oracle oinstall 210823844 Jul 31 13:21 oracle
[oracle@pldb236 bin]$ 



[oracle@pldb236 bin]$ rlwrap sqlplus / as sysdba

SQL*Plus: Release 11.2.0.1.0 Production on Mon Nov 23 14:20:09 2015

Copyright (c) 1982, 2009, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> 
SQL>

ok可以连接上了，问题初步解决

3，不过3分钟后，又不行了，登录不上去。

SQL*Plus: Release 11.2.0.1.0 Production on Mon Nov 23 14:29:17 2015

Copyright (c) 1982, 2009, Oracle. All rights reserved.

ERROR:
ORA-12537: TNS:connection closed

Enter user-name:

去查看lsnrctl状态：
[oracle@pldb236 bin]$ lsnrctl status

LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 23-NOV-2015 14:30:33

Copyright (c) 1991, 2009, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.180.236)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 11.2.0.1.0 - Production
Start Date                23-NOV-2015 14:30:19
Uptime                    0 days 0 hr. 0 min. 13 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /oracle/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora
Listener Log File         /oracle/app/oracle/diag/tnslsnr/pldb236/listener/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.180.236)(PORT=1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC0)))
Services Summary...
Service "PLSExtProc" has 1 instance(s).
  Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "powerdes" has 1 instance(s).
  Instance "powerdes", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully
[oracle@pldb236 bin]$

看到后台alert的日志报错如下：

Mon Nov 23 14:32:00 2015
        ORA-00020: maximum number of processes 150 exceeded
        ORA-20 errors will not be written to the alert log for
         the next minute. Please look at trace files to see all
         the ORA-20 errors.
        Mon Nov 23 14:32:47 2015
        Process m000 submission failed with error = 20
        Mon Nov 23 14:33:02 2015
        ORA-00020: maximum number of processes 150 exceeded
        ORA-20 errors will not be written to the alert log for
         the next minute. Please look at trace files to see all
         the ORA-20 errors.
        Mon Nov 23 14:34:03 2015
        ORA-00020: maximum number of processes 150 exceeded
        ORA-20 errors will not be written to the alert log for
         the next minute. Please look at trace files to see all
         the ORA-20 errors.

解决方案1：
lsnrctl stop 5分钟后，再lsnrctl start起来，问题解决了，是应用程序一直不停的连接数据库，占满了连接池导致的。

解决方案2：
查看oracle的连接数，果然为150

SQL> show parameter processes;

NAME                     TYPE    VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes              integer     0
db_writer_processes          integer     2
gcs_server_processes             integer     0
global_txn_processes             integer     1
job_queue_processes          integer     1000
log_archive_max_processes        integer     4
processes                integer     150
SQL> 
SQL> 
SQL>

分析原因：

SQL> select count(1) from v$session t where t.status='INACTIVE' and t.username='PLAS';
  COUNT(1)
----------
        88

SQL> 
SQL> 
SQL> select count(1) from v$session t where t.status='INACTIVE' and t.username='PLAS';
  COUNT(1)
----------
         5

SQL>

修改配置文件：

[oracle@pldb236 ~]$ find /oracle -name *init.ora*
/oracle/app/oracle/product/11.2.0/dbhome_1/dbs/init.ora
/oracle/app/oracle/product/11.2.0/dbhome_1/srvm/admin/init.ora
/oracle/app/oracle/admin/powerdes/pfile/init.ora.7112015171232
[oracle@pldb236 ~]$

改动连接数，并且写入参数文件

alter system set processes=500 scope = spfile;
SQL> alter system set processes=500 scope=spfile;

System altered.

SQL> create pfile from spfile;

File created.

SQL>

关闭重启oracle实例，启动就可以看到最大连接数已经变成了500，问题解决