今天一网友咨询数据库宕机了，当时数据库出现用户无法登录的症状，为了了解起因，去查看了网友的告警日志alert.log，发现在晚上1
今天一网友咨询数据库宕机了，当时数据库出现用户无法登录的症状，为了了解起因，去查看了网友的告警日志alert.log，发现在晚上10:00左右出现大量的ora-00020: no more process state objects available 错误，具体错误日志如下:
fatal ni connect error 12170.
  version information:
  tns for linux: version 11.2.0.2.0 - production
  oracle bequeath nt protocol adapter for linux: version 11.2.0.2.0 - production
  tcp/ip nt protocol adapter for linux: version 11.2.0.2.0 - production
  time: 11-may-2015 14:28:28
  tracing not turned on.
  tns error struct:
    ns main err code: 12535
tns-12535: tns:operation timed out
    ns secondary err code: 12560
    nt main err code: 505
tns-00505: operation timed out
    nt secondary err code: 110
    nt os err code: 0
  client address: (address=(protocol=tcp)(host=192.168.102.150)(port=50069))
 mon may 11 16:21:14 2015
 thread 1 cannot allocate new log, sequence 1728
 private strand flush not complete
  current log# 4 seq# 1727 mem# 0: /oradata/orcl/redo4.log
 thread 1 advanced to log sequence 1728 (lgwr switch)
  current log# 3 seq# 1728 mem# 0: /oradata/orcl/redo3.log
 mon may 11 22:00:00 2015
 setting resource manager plan scheduler[0x3107]:default_maintenance_plan via scheduler window
 setting resource manager plan default_maintenance_plan via parameter
 mon may 11 22:00:00 2015
 starting background process vkrm
 mon may 11 22:00:00 2015
 vkrm started with pid=83, os id=27195
 tue may 12 00:56:23 2015
 thread 1 cannot allocate new log, sequence 1729
 private strand flush not complete
  current log# 3 seq# 1728 mem# 0: /oradata/orcl/redo3.log
 thread 1 advanced to log sequence 1729 (lgwr switch)
  current log# 1 seq# 1729 mem# 0: /oradata/orcl/redo01.log
 tue may 12 02:00:00 2015
 closing scheduler window
 closing resource manager plan via scheduler window
 clearing resource manager plan via parameter
 tue may 12 10:46:48 2015
 thread 1 cannot allocate new log, sequence 1730
 private strand flush not complete
  current log# 1 seq# 1729 mem# 0: /oradata/orcl/redo01.log
 thread 1 advanced to log sequence 1730 (lgwr switch)
  current log# 2 seq# 1730 mem# 0: /oradata/orcl/redo2.log
 tue may 12 14:36:13 2015
 thread 1 cannot allocate new log, sequence 1731
 private strand flush not complete
  current log# 2 seq# 1730 mem# 0: /oradata/orcl/redo2.log
 thread 1 advanced to log sequence 1731 (lgwr switch)
  current log# 4 seq# 1731 mem# 0: /oradata/orcl/redo4.log
 tue may 12 16:27:07 2015
 thread 1 cannot allocate new log, sequence 1732
 private strand flush not complete
  current log# 4 seq# 1731 mem# 0: /oradata/orcl/redo4.log
 thread 1 advanced to log sequence 1732 (lgwr switch)
  current log# 3 seq# 1732 mem# 0: /oradata/orcl/redo3.log
 tue may 12 22:00:00 2015
 setting resource manager plan scheduler[0x3108]:default_maintenance_plan via scheduler window
 setting resource manager plan default_maintenance_plan via parameter
 tue may 12 22:00:00 2015
 starting background process vkrm
 tue may 12 22:00:00 2015
 vkrm started with pid=174, os id=25804
 wed may 13 02:00:00 2015
 closing scheduler window
 closing resource manager plan via scheduler window
 clearing resource manager plan via parameter
 wed may 13 02:45:10 2015
 thread 1 cannot allocate new log, sequence 1733
 private strand flush not complete
  current log# 3 seq# 1732 mem# 0: /oradata/orcl/redo3.log
 thread 1 advanced to log sequence 1733 (lgwr switch)
  current log# 1 seq# 1733 mem# 0: /oradata/orcl/redo01.log
 wed may 13 09:05:36 2015
 time drift detected. please check vktm trace file for more details.
 wed may 13 09:15:55 2015
 dm00 started with pid=352, os id=4784, job system.sys_export_schema_01
 wed may 13 09:15:56 2015
 dw00 started with pid=353, os id=4786, wid=1, job system.sys_export_schema_01
 wed may 13 10:11:52 2015
 thread 1 cannot allocate new log, sequence 1734
 private strand flush not complete
  current log# 1 seq# 1733 mem# 0: /oradata/orcl/redo01.log
 thread 1 advanced to log sequence 1734 (lgwr switch)
  current log# 2 seq# 1734 mem# 0: /oradata/orcl/redo2.log
 wed may 13 13:15:38 2015
 thread 1 cannot allocate new log, sequence 1735
 private strand flush not complete
  current log# 2 seq# 1734 mem# 0: /oradata/orcl/redo2.log
 thread 1 advanced to log sequence 1735 (lgwr switch)
  current log# 4 seq# 1735 mem# 0: /oradata/orcl/redo4.log
 wed may 13 14:54:18 2015
 thread 1 cannot allocate new log, sequence 1736
 private strand flush not complete
  current log# 4 seq# 1735 mem# 0: /oradata/orcl/redo4.log
 thread 1 advanced to log sequence 1736 (lgwr switch)
  current log# 3 seq# 1736 mem# 0: /oradata/orcl/redo3.log
 wed may 13 17:39:31 2015
 thread 1 cannot allocate new log, sequence 1737
 private strand flush not complete
  current log# 3 seq# 1736 mem# 0: /oradata/orcl/redo3.log
 thread 1 advanced to log sequence 1737 (lgwr switch)
  current log# 1 seq# 1737 mem# 0: /oradata/orcl/redo01.log
 wed may 13 20:47:10 2015
 ora-00020: no more process state objects available
 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.
 process m000 submission failed with error = 20
 wed may 13 20:52:37 2015
 ora-00020: no more process state objects available
 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.
 process m000 submission failed with error = 20
 wed may 13 20:57:38 2015
 ora-00020: no more process state objects available
 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.
 process m000 submission failed with error = 20
 wed may 13 21:01:35 2015
 ora-00020: no more process state objects available
 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.
 process w001 submission failed with error = 20
 wed may 13 21:02:38 2015
 ora-00020: no more process state objects available
 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.
 process m001 submission failed with error = 20
 wed may 13 21:05:44 2015
 ora-00020: no more process state objects available
 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.
 process w001 submission failed with error = 20
 wed may 13 21:12:38 2015
 ora-00020: no more process state objects available
 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.
 process m000 submission failed with error = 20
 process m001 submission failed with error = 20
 wed may 13 21:42:39 2015
 ora-00020: no more process state objects available
 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.
 process m000 submission failed with error = 20
 process m001 submission failed with error = 20
 wed may 13 21:43:00 2015
 process w001 submission failed with error = 20
 wed may 13 21:51:13 2015
 adjusting the default value of parameter parallel_max_servers
 from 1280 to 385 due to the value of parameter processes (400)
 starting oracle instance (normal)
 wed may 13 21:52:40 2015
 ora-00020: no more process state objects available
 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.
 process m000 submission failed with error = 20
 wed may 13 21:53:33 2015
错误信息一般在oracle实例在创建一些辅助后台进程(如mmon的子进程m00x或者子进程w00x等)时出现进程启动失败时出现，而造成该错误的可能性有多种，包括oracle实例资源不足、操作系统资源不足等等。其中较为常见的是实例instance的process使用达到上限，可以通过查询v$resource_limit视图来了解实例生命周期内是否发生过process总数暴满的情况:
我们可以看到processes的max_utilization最大使用数目曾到过limit_value限定的400，，
 sessions达到了640.
从以上v$resource_limit视图的输出来看，极有可能是processes总数达到上限导致了新的后台辅助进程创建失败，其实我们可以很方便地验证这一点:
[oracle@bntjftest ~]$ sqlplus / as sysdba
sql*plus: release 11.2.0.4.0 production on thu may 14 15:28:15 2015
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