[HBASE-4965] Monitor the open file descriptors and the threads counters during the unit tests

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.94.0
• Fix Version/s: 0.94.0
• Component/s: test

Environment

all

• Hadoop Flags: Reviewed
• Assignee: Nicolas Liochon
• Reporter: Nicolas Liochon
• Created: 06/Dec/11 11:43
• Updated: 12/Oct/12 05:35
• Resolved: 12/Dec/11 21:50

Description

We're seeing a lot of issues with hadoop-qa related to threads or file descriptors.
Monitoring these counters would ease the analysis.

Note as well that

• if we want to execute the tests in the same jvm (because the test is small or because we want to share the cluster) we can't afford to leak too many resources
• if the tests leak, it's more difficult to detect a leak in the software itself.

I attach piece of code that I used. It requires two lines in a unit test class to:

• before every test, count the threads and the open file descriptor
• after every test, compare with the previous value.

I ran it on some tests; we have for example:

• client.TestMultiParallel#testBatchWithManyColsInOneRowGetAndPut: 232 threads (was 231), 390 file descriptors (was 390). => TestMultiParallel uses 232 threads!
• client.TestMultipleTimestamps#testWithColumnDeletes: 152 threads (was 151), 283 file descriptors (was 282).
• client.TestAdmin#testCheckHBaseAvailableClosesConnection: 477 threads (was 294), 815 file descriptors (was 461)
• client.TestMetaMigrationRemovingHTD#testMetaMigration: 149 threads (was 148), 310 file descriptors (was 307).

It's not always leaks, we can expect some pooling effects. But still...

Issue Links

• is required by: HBASE-4602 Make the suite run in at least half the time
• relates to: HBASE-4974 Remove some resources leaks on the tests