https://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2019-January/024465.html


My customer uses OpenJDK 8u131 with following commandline arguments:

   -XX:+CMSClassUnloadingEnabled -XX:CMSInitiatingOccupancyFraction=80
   -XX:CompressedClassSpaceSize=128m -Xms4500m -Xmx4500m
   -XX:MaxMetaspaceSize=256m -Xmn=768m -XX:MaxTenuringThreshold=15
   -XX:OnOutOfMemoryError="/bin/kill -ABRT %p"
   -XX:+UseCMSInitiatingOccupancyOnly -XX:+UseConcMarkSweepGC

Their system has encountered OutOfMemoryError which is caused by Metaspace.

I checked core image which was collected by OnOutOfMemoryError, and I saw
strange values in it as below:

-------------------
(gdb) p Metaspace::_space_list->_reserved_words
$67 = 31195136
(gdb) p Metaspace::_class_space_list->_reserved_words
$68 = 16777216
(gdb) p MetaspaceGC::_capacity_until_GC
$75 = 448045056
-------------------