The following tests timeout periodically in the loom repo:

java/lang/Thread/virtual/NetSockets.java#id0
java/lang/Thread/virtual/NetSockets.java#id1
java/lang/Thread/virtual/NioChannels.java#id0
java/lang/Thread/virtual/NioChannels.java#id1

There are at least two failure modes:

1. A timeout/hang with no additional information. It seems to only happen on Windows Server 2012 and Windows Server 2016 systems, I haven't seen any sightings on new releases of Windows.

2. A timeout/hang when re-running with WSAPollPoller where we see the following exception in the log:

 java.lang.NullPointerException: Cannot invoke "java.lang.Integer.intValue()" because the return value of "java.util.Map.get(Object)" is null
at java.base/sun.nio.ch.WSAPollPoller.processEvents(WSAPollPoller.java:212)
at java.base/sun.nio.ch.WSAPollPoller.poll(WSAPollPoller.java:159)
at java.base/sun.nio.ch.Poller.poll(Poller.java:363)
at java.base/sun.nio.ch.Poller.pollLoop(Poller.java:270)
at java.base/java.lang.Thread.run(Thread.java:1510)
at java.base/jdk.internal.misc.InnocuousThread.run(InnocuousThread.java:162)