DirectBufferAllocTest.java causes OOM

[adamfarley]

Describe the bug
OOM produced by DirectBufferAllocTest.java

01:02:03  Allocating direct ByteBuffers with capacity 1048576 bytes, using 40 threads for 5 seconds...
01:02:03  STDERR:
01:02:03  java.lang.RuntimeException: Errors encountered!
01:02:03  	at DirectBufferAllocTest.main(DirectBufferAllocTest.java:157)
01:02:03  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
01:02:03  	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
01:02:03  	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
01:02:03  	at java.base/java.lang.reflect.Method.invoke(Method.java:564)
01:02:03  	at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
01:02:03  	at java.base/java.lang.Thread.run(Thread.java:832)
01:02:03  	Suppressed: java.lang.OutOfMemoryError: Cannot reserve 1048576 bytes of direct buffer memory (allocated: 134217728, limit: 134217728)
01:02:03  		at java.base/java.nio.Bits.reserveMemory(Bits.java:178)
01:02:03  		at java.base/java.nio.DirectByteBuffer.<init>(DirectByteBuffer.java:120)
01:02:03  		at java.base/java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:329)
01:02:03  		at DirectBufferAllocTest.lambda$main$0(DirectBufferAllocTest.java:126)
01:02:03  		at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
01:02:03  		at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
01:02:03  		at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
01:02:03  		... 1 more

To Reproduce
https://ci.adoptopenjdk.net/job/Test_openjdk14_hs_sanity.openjdk_ppc64_aix/111/console

Expected behavior
We expect no OOMs.

Additional context
The test was explicitly created to elicit this kind of error, so the original bug that the test was created for could be useful.

Also, if the fix for this results in a 100% pass rate on openj9, close this issue when resolved

[smlambert]

I do not see this failing in Hotspot builds: https://ci.adoptopenjdk.net/job/Test_openjdk15_hs_sanity.openjdk_ppc64_aix/77/testReport/java_nio_Buffer_DirectBufferAllocTest/

So, contrary to the comment in the OpenJ9 issue eclipse-openj9/openj9#4473 (comment), this is not a Hotspot issue.

This needs to be retested against OpenJ9, and if only failing there, we will close this issue as its tracked under OpenJ9 4473.

[smlambert]

To be sure, I will grinderize it against hotspot, as I see its an intermittent failure at best.