ORA-12516故障解决-mysql教程

早上刚上班，同事告诉我数据库连不上了，提示ldquo;ORA-12516rdquo;错误，我尝试通过PL/SQL Developer远程连接数据库，果然，报

早上刚上班，同事告诉我数据库连不上了，提示“ORA-12516”错误，，我尝试通过PL/SQL Developer远程连接数据库，果然，报错了“ORA-12516: TNS: 监听程序无法找到匹配协议栈的可用句柄”；接着我通过远程桌面登录服务器，尝试用sys用户登录数据库，报了同样的错误。奇怪，昨天下班时还好好的。

我上网查了一下，这个报错一般是由于数据库的当前会话数不足造成的，相关的参数有两个：processes和sessions。我想查一下数据库这两个参数，但是sys用户无法登陆，真是着急。后来在朋友的建议下，采取以下步骤，顺利解决了这个问题。

a.关闭listener，禁止新的连接；
b.杀掉local=no的部分或者全部进程（根据业务的重要性），杀掉几个，保证sys用户能登陆；
c.登进去看看哪个业务出问题了，杀掉出问题的用户进程；
d.检查数据库；
e.启动listener；

介绍一下我的操作环境：
操作系统：Windows Server 2008 R2
数据库：Oracle 10g

首先，通过lsnrctl stop关闭监听器，禁止新的连接，以确保第二步能够执行成功；
第二，关闭了两个连接数据库的应用程序，然后尝试用sys用户登录数据库，登录成功；
第三，查看了processes和sessions两个初始化参数值，分别为150、170，均为默认值；

SQL>

SQL> show parameter processes

NAME TYPE VALUE

------------------------------------ ----------- ------------------------------

aq_tm_processes integer 0

db_writer_processes integer 3

gcs_server_processes integer 0

job_queue_processes integer 10

log_archive_max_processes integer 2

processes integer 150

SQL> show parameter sessions

NAME TYPE VALUE

------------------------------------ ----------- ------------------------------

java_max_sessionspace_size integer 0

java_soft_sessionspace_limit integer 0

license_max_sessions integer 0

license_sessions_warning integer 0

logmnr_max_persistent_sessions integer 1

sessions integer 170

shared_server_sessions integer

SQL>
第四，通过select sid,serial#,program,terminal from v$session;查看当前所有会话信息，从当时的结果可以看到，有一百多条记录，已经超过了数据库的session上限；而且，除了Oracle自身的十几个会话外，其余一百多个会话都是同一个terminal。由此，找出了故障点所在（这台设备是昨晚刚刚安装的一台终端）。
第五，关闭故障设备上的应用程序，再次通过select sid,serial#,program,terminal from v$session;查看当前所有会话信息，查询结果显示只剩下二十多条会话信息，考虑到Oracle自身的十几个会话外和同时启动的几个应用程序，应该是正常的；
第六，启动listener，尝试通过其他客户端连接数据库，一切正常，到此故障解决；
接下来，我想看一下究竟是什么原因导致了这次故障，继续；
第七，查看报警日志，在日志中看到了大量的Process m000 died报警；

Wed Apr 29 21:27:31 2015

ksvcreate: Process(m000) creation failed

Wed Apr 29 21:28:32 2015

Process m000 died, see its trace file

Wed Apr 29 21:28:32 2015

ksvcreate: Process(m000) creation failed

Wed Apr 29 21:29:33 2015

Process m000 died, see its trace file
第八，找到对应时间的trace文件，看到了“ORA-00020: maximum number of processes 150 exceeded Died during process startup with error 20 (seq=5413)”语句，原来是连接数超过了阀值，数据库无法再建立新的连接，所以报错。

Dump file c:\\oracle\\product\\10.2.0\\admin\\hoegh\\bdump\\hoegh_ora_8032.trc

Wed Apr 29 21:28:31 2015

ORACLE V10.2.0.4.0 - 64bit Production vsnsta=0

vsnsql=14 vsnxtr=3

Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

Windows NT Version V6.1 Service Pack 1

CPU : 24 - type 8664, 12 Physical Cores

Process Affinity : 0x0000000000000000

Memory (Avail/Total): Ph:3339M/8181M, Ph+PgF:10815M/16361M

Instance name: hoegh

Redo thread mounted by this instance: 1

Oracle process number: 0

Windows thread id: 8032, image: ORACLE.EXE

ORA-00020: maximum number of processes 150 exceeded

Died during process startup with error 20 (seq=5413)

OPIRIP: Uncaught error 20. Error stack:

ORA-00020: maximum number of processes (150) exceeded

Dump file c:\\oracle\\product\\10.2.0\\admin\\hoegh\\bdump\\hoegh_ora_8032.trc

Thu Apr 30 00:19:05 2015

ORACLE V10.2.0.4.0 - 64bit Production vsnsta=0

vsnsql=14 vsnxtr=3

Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

Windows NT Version V6.1 Service Pack 1

CPU : 24 - type 8664, 12 Physical Cores

Process Affinity : 0x0000000000000000

Memory (Avail/Total): Ph:3347M/8181M, Ph+PgF:10813M/16361M

Instance name: hoegh

Redo thread mounted by this instance: 1

Oracle process number: 0

Windows thread id: 8032, image: ORACLE.EXE

ORA-00020: maximum number of processes 150 exceeded

Died during process startup with error 20 (seq=5582)

OPIRIP: Uncaught error 20. Error stack:

ORA-00020: maximum number of processes (150) exceeded

Dump file c:\\oracle\\product\\10.2.0\\admin\\hoegh\\bdump\\hoegh_ora_8032.trc

Thu Apr 30 01:27:31 2015

ORACLE V10.2.0.4.0 - 64bit Production vsnsta=0

vsnsql=14 vsnxtr=3

Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

Windows NT Version V6.1 Service Pack 1

CPU : 24 - type 8664, 12 Physical Cores

Process Affinity : 0x0000000000000000

Memory (Avail/Total): Ph:3350M/8181M, Ph+PgF:10812M/16361M

Instance name: hoegh

Redo thread mounted by this instance: 1

Oracle process number: 0

Windows thread id: 8032, image: ORACLE.EXE

ORA-00020: maximum number of processes 150 exceeded

Died during process startup with error 20 (seq=5650)

OPIRIP: Uncaught error 20. Error stack:

ORA-00020: maximum number of processes (150) exceeded

Dump file c:\\oracle\\product\\10.2.0\\admin\\hoegh\\bdump\\hoegh_ora_8032.trc

Thu Apr 30 09:54:12 2015

ORACLE V10.2.0.4.0 - 64bit Production vsnsta=0

vsnsql=14 vsnxtr=3

Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

Windows NT Version V6.1 Service Pack 1

CPU : 24 - type 8664, 12 Physical Cores

Process Affinity : 0x0000000000000000

Memory (Avail/Total): Ph:3857M/8181M, Ph+PgF:11421M/16361M

Instance name: hoegh

Redo thread mounted by this instance: 1

Oracle process number: 0