> Nope - no swap enabled. Something is seriously weird, unless the system clock is broken... Given:
INFO [GC inspection] 2010-09-20 15:27:42,046 GCInspector.java (line 129) GC for ParNew: 325411 ms, 84284896 reclaimed leaving 640770336 used; max is 25907560448 INFO [GC inspection] 2010-09-20 15:34:15,924 GCInspector.java (line 129) GC for ParNew: 372272 ms, 82471240 reclaimed leaving 671616240 used; max is 25907560448 We have *extremely* slow ParNew:s on a heap that is not even close to being full. I highly doubt fragmentation is causing this kind of extremity. I wonder if it is possible that EC2 instances are over-committed on memory such that swapping is happening behind the scenes on the host... but I have always assumed memory was not over-committed on EC2. Can you run with -XX:+PrintGC -XX:+PrintGCDetails -XX:+PrintGCTimestamps? -- / Peter Schuller