I should add: If you are indeed actually pausing due to "promotion failed" or "concurrent mode failure" (which you will see in the GC log if you enable it with the options I suggested), the first thing I would try to mitigate is:
* Decrease the occupancy trigger (search for "occupancy") of CMS to a lower percentage, making the concurrent mark phase start earlier. * Increase heap size significantly (probably not necessary based on your graph, but for good measure). If it then goes away, report back and we can perhaps figure out details. There are other things that can be done. -- / Peter Schuller (@scode, http://worldmodscode.wordpress.com)