[HADOOP-7255] Performance regression bug caused by locking code

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 0.20.203.0
• Assignee: Unassigned
• Reporter: T Jake Luciani
• Created: 03/May/11 01:49
• Updated: 03/May/11 11:33

Description

While testing the 0.20.203 branch we have discovered quite a severe performance regression caused by the following checkin:

http://svn.apache.org/viewvc?view=revision&revision=1079260

This locking seems to cause a pause of a few seconds between tasks, example with DFSIOTest:

CURRENT CODE

11/05/02 21:16:28 INFO fs.TestDFSIO: ----- TestDFSIO ----- : read
11/05/02 21:16:28 INFO fs.TestDFSIO:            Date & time: Mon May 02 21:16:28 EDT 2011
11/05/02 21:16:28 INFO fs.TestDFSIO:        Number of files: 5
11/05/02 21:16:28 INFO fs.TestDFSIO: Total MBytes processed: 500
11/05/02 21:16:28 INFO fs.TestDFSIO:      Throughput mb/sec: 303.3980582524272
11/05/02 21:16:28 INFO fs.TestDFSIO: Average IO rate mb/sec: 327.69122314453125
11/05/02 21:16:28 INFO fs.TestDFSIO:  IO rate std deviation: 78.95767116969083
11/05/02 21:16:28 INFO fs.TestDFSIO:     Test exec time sec: 19.476
11/05/02 21:16:28 INFO fs.TestDFSIO: 

WITH PATCH REMOVED

11/05/02 21:19:03 INFO fs.TestDFSIO: ----- TestDFSIO ----- : read
11/05/02 21:19:03 INFO fs.TestDFSIO:            Date & time: Mon May 02 21:19:03 EDT 2011
11/05/02 21:19:03 INFO fs.TestDFSIO:        Number of files: 5
11/05/02 21:19:03 INFO fs.TestDFSIO: Total MBytes processed: 500
11/05/02 21:19:03 INFO fs.TestDFSIO:      Throughput mb/sec: 366.03221083455344
11/05/02 21:19:03 INFO fs.TestDFSIO: Average IO rate mb/sec: 366.35528564453125
11/05/02 21:19:03 INFO fs.TestDFSIO:  IO rate std deviation: 11.020931463080379
11/05/02 21:19:03 INFO fs.TestDFSIO:     Test exec time sec: 3.543
11/05/02 21:19:03 INFO fs.TestDFSIO: