[HBASE-21097] Flush pressure assertion may fail in testFlushThroughputTuning

• Type: Test
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.0.0, 2.2.0, 2.1.1, 2.0.3
• Component/s: regionserver
• Hadoop Flags: Reviewed
• Assignee: Ted Yu
• Reporter: Ted Yu
• Created: 22/Aug/18 19:23
• Updated: 16/Sep/18 12:17
• Resolved: 15/Sep/18 12:58

Description

From https://builds.apache.org/job/PreCommit-HBASE-Build/14137/artifact/patchprocess/patch-unit-hbase-server.txt :

[ERROR] testFlushThroughputTuning(org.apache.hadoop.hbase.regionserver.throttle.TestFlushWithThroughputController)  Time elapsed: 17.446 s  <<< FAILURE!
java.lang.AssertionError: expected:<0.0> but was:<1.2906294173808417E-6>
	at org.apache.hadoop.hbase.regionserver.throttle.TestFlushWithThroughputController.testFlushThroughputTuning(TestFlushWithThroughputController.java:185)

Here is the related assertion:

    assertEquals(0.0, regionServer.getFlushPressure(), EPSILON);

where EPSILON = 1E-6

In the above case, due to margin of 2.9E-7, the assertion didn't pass.
It seems the epsilon can be adjusted to accommodate different workload / hardware combination.