If HBaseTestClassRule timesout a test, thread dump.

We set look for stuck thread in our timeout rule but it is super conservative in what it prints.. it looks for a RUNNABLE thread and prints first found ONLY. Pretty useless for us. If a test timesout, often the printing has stopped in the stderr/stdout.

I'm trying to debug TestAsyncRegionAdminApi. It says test timed out after 10 minutes but we've stopped printing to the logs and here is what junit prints:

-------------------------------------------------------------------------------
Test set: org.apache.hadoop.hbase.client.TestAsyncRegionAdminApi
-------------------------------------------------------------------------------
Tests run: 25, Failures: 0, Errors: 2, Skipped: 2, Time elapsed: 572.508 s <<< FAILURE! - in org.apache.hadoop.hbase.client.TestAsyncRegionAdminApi
org.apache.hadoop.hbase.client.TestAsyncRegionAdminApi Time elapsed: 14.642 s <<< ERROR!
org.junit.runners.model.TestTimedOutException: test timed out after 600 seconds
at org.apache.hadoop.hbase.client.TestAsyncRegionAdminApi.testMergeRegions(TestAsyncRegionAdminApi.java:363)

org.apache.hadoop.hbase.client.TestAsyncRegionAdminApi Time elapsed: 14.642 s <<< ERROR!
java.lang.Exception: Appears to be stuck in thread Socket Reader #1 for port 35917