test/jdk/java/lang/management/MemoryMXBean/LowMemoryTest2.sh

rev 60538 : imported patch jep387-test.patch

@@ -60,10 +60,19 @@
 go -noclassgc -XX:MaxMetaspaceSize=32m -XX:+UseSerialGC LowMemoryTest2
 go -noclassgc -XX:MaxMetaspaceSize=32m -XX:+UseParallelGC LowMemoryTest2
 
 # Test class metaspace - might hit MaxMetaspaceSize instead if
 # UseCompressedClassPointers is off or if 32 bit.
+#
+# (note: This is very shaky and that shakiness exposes a problem with MemoryMXBean:
+#
+#  MemoryMXBean defines "used" "committed" and "max" (see java/lang/management/MemoryUsage.java)
+#  This abstraction misses a definition for "address space exhausted" which with the new Metaspace (jep387)
+#  can happen before committed/used hits any trigger. We now commit only on demand and therefore class loaders
+#  can sit atop of uncommitted address space, denying new loaders address space. In the old Metaspace,
+#  we would have committed the space right away and therefore the MemoryMXBean "committed" trigger
+#  would have fired. In the new Metaspace, we don't commit, so the MemoryMXBean does not fire.
 go -noclassgc -XX:MaxMetaspaceSize=16m -XX:CompressedClassSpaceSize=4m LowMemoryTest2
 
 echo ''
 if [ $failures -gt 0 ];
   then echo "$failures test(s) failed";