在生产环境下，几乎每天都会发生一次数据库被几百个insert和update堵死
造成应用中间件死掉
这个时候查看oracle是没有锁的，所以肯定排除掉了死锁的可能性
如下内容为数据库日志（有朋友说是redo过小造成的，但放大到多少合适呢？）
Thu Jan 10 09:53:03 2013
Thread 1 cannot allocate new log, sequence 5024
Checkpoint not complete
Current log# 1 seq# 5023 mem# 0: +DATA/gx/onlinelog/group_1.667.802435761
Current log# 1 seq# 5023 mem# 1: +DATA/gx/onlinelog/group_1.647.802435765
Thu Jan 10 09:53:46 2013
Thread 1 advanced to log sequence 5024 (LGWR switch)
Current log# 2 seq# 5024 mem# 0: +DATA/gx/onlinelog/group_2.669.802435767
Current log# 2 seq# 5024 mem# 1: +DATA/gx/onlinelog/group_2.668.802435771
Thu Jan 10 09:55:13 2013
Thread 1 cannot allocate new log, sequence 5025
Checkpoint not complete
Current log# 2 seq# 5024 mem# 0: +DATA/gx/onlinelog/group_2.669.802435767
Current log# 2 seq# 5024 mem# 1: +DATA/gx/onlinelog/group_2.668.802435771
Thu Jan 10 09:55:51 2013
AUD: Audit Commit Delay exceeded, written a copy to OS Audit Trail
Thu Jan 10 09:55:51 2013
AUD: Audit Commit Delay exceeded, written a copy to OS Audit Trail
Thu Jan 10 09:55:52 2013
Thread 1 advanced to log sequence 5025 (LGWR switch)
Current log# 3 seq# 5025 mem# 0: +DATA/gx/onlinelog/group_3.267.802435775
Current log# 3 seq# 5025 mem# 1: +DATA/gx/onlinelog/group_3.266.802435779
Thu Jan 10 09:57:05 2013
Thread 1 cannot allocate new log, sequence 5026
Checkpoint not complete
Current log# 3 seq# 5025 mem# 0: +DATA/gx/onlinelog/group_3.267.802435775
Current log# 3 seq# 5025 mem# 1: +DATA/gx/onlinelog/group_3.266.802435779
Thu Jan 10 09:57:46 2013
Thread 1 advanced to log sequence 5026 (LGWR switch)
Current log# 1 seq# 5026 mem# 0: +DATA/gx/onlinelog/group_1.667.802435761
Current log# 1 seq# 5026 mem# 1: +DATA/gx/onlinelog/group_1.647.802435765
Thu Jan 10 09:57:47 2013
AUD: Audit Commit Delay exceeded, written a copy to OS Audit Trail
Thu Jan 10 09:59:01 2013
Thread 1 cannot allocate new log, sequence 5027
Checkpoint not complete
Current log# 1 seq# 5026 mem# 0: +DATA/gx/onlinelog/group_1.667.802435761
Current log# 1 seq# 5026 mem# 1: +DATA/gx/onlinelog/group_1.647.802435765
Thu Jan 10 09:59:40 2013
Thread 1 advanced to log sequence 5027 (LGWR switch)
Current log# 2 seq# 5027 mem# 0: +DATA/gx/onlinelog/group_2.669.802435767
Current log# 2 seq# 5027 mem# 1: +DATA/gx/onlinelog/group_2.668.802435771
Thu Jan 10 10:00:53 2013