在9.2.0.8 RAC环境中，告警日志频繁出现内存分配错误的信息。
错误信息如下：
Wed May 2 10:20:43 2012 Trace dumping IS performing id=[cdmp_20120502102043] There are 1444 memory allocation errors FOR object-level stat IN the LAST 15 minutes . . . There are 1605 memory allocation errors FOR object-level stat IN the LAST 15 minutes |
在另外一个节点上则出现了ORA-4031错误：
Sun Apr 29 22:30:52 2012 Errors IN file /oracle/admin/orcl/bdump/orcl2_j000_1204632.trc: ORA-12012: error ON auto EXECUTE OF job 527 ORA-04031: unable TO allocate 4224 bytes OF shared memory ("shared pool","unknown object","sga heap(2,0)","object level s") ORA-06512: at "PERFSTAT.STATSPACK", line 2479 ORA-06512: at "PERFSTAT.STATSPACK", line 91 ORA-06512: at line 1 Sun Apr 29 23:03:14 2012 Errors IN file /oracle/admin/orcl/bdump/orcl2_j001_1528536.trc: ORA-12012: error ON auto EXECUTE OF job 527 ORA-04031: unable TO allocate 4256 bytes OF shared memory ("shared pool","unknown object","sga heap(2,0)","obj stat memor") ORA-06512: at "PERFSTAT.STATSPACK", line 2479 ORA-06512: at "PERFSTAT.STATSPACK", line 91 ORA-06512: at line 1 There IS 1 memory allocation error FOR object-level stat IN the LAST 15 minutes There are 66 memory allocation errors FOR object-level stat IN the LAST 15 minutes There are 8 memory allocation errors FOR object-level stat IN the LAST 15 minutes Mon Apr 30 00:07:38 2012 Errors IN file /oracle/admin/orcl/bdump/orcl2_j001_942754.trc: ORA-12012: error ON auto EXECUTE OF job 527 ORA-04031: unable TO allocate 4256 bytes OF shared memory ("shared pool","unknown object","sga heap(2,0)","obj stat memor") ORA-06512: at "PERFSTAT.STATSPACK", line 2479 ORA-06512: at "PERFSTAT.STATSPACK", line 91 ORA-06512: at line 1 There are 354 memory allocation errors FOR object-level stat IN the LAST 15 minutes There are 653 memory allocation errors FOR object-level stat IN the LAST 15 minutes Mon Apr 30 02:07:45 2012 Thread 2 advanced TO log SEQUENCE 71531 CURRENT log# 5 seq# 71531 mem# 0: /dev/rlv_redo22_128m Mon Apr 30 02:07:45 2012 ARC0: Evaluating archive log 4 thread 2 SEQUENCE 71530 ARC0: Beginning TO archive log 4 thread 2 SEQUENCE 71530 Creating archive destination LOG_ARCHIVE_DEST_1: '/archive2/2_71530.dbf' ARC0: Completed archiving log 4 thread 2 SEQUENCE 71530 There are 41 memory allocation errors FOR object-level stat IN the LAST 15 minutes |
ORA-4031错误比较常见，简单的说就是内存不足所致。从上面的错误信息看，内存不足发生在共享池上。而Memory allocation errors同样是共享池空间不足的表现，可以参考文章Memory Allocation Errors For Object-Level Stat Appearing in the Alert Log File [ID 757895.1]。
针对这个问题，可以通过设置隐含参数_OBJECT_STATISTICS=FALSE来禁用对象级统计信息，但是最彻底的方法还是增加共享池空间。