Bug 769936

+++ This bug was initially created as a clone of Bug #752981 +++

When void org.rhq.plugins.platform.FileSystemComponent.getValues(MeasurementReport report, Set<MeasurementScheduleRequest> metrics) throws Exception is executed it first creates an instance of FileSystemInfo on line 73[1] and then calls the FileSystemInfo refresh method on line 74. The call on line 74 is a duplicate of the refresh called during the creation of the FileSystemInfo object as this is what it does in its constructor[2].


Although this is minor, it does have a performance impact when many metrics are enabled, collected frequently, and there are multiple file systems on the platform being monitored. 

Not certain to which call should actually be occurring but this should probably be cleaned up.


[1]: http://git.fedorahosted.org/git?p=rhq/rhq.git;a=blob;f=modules/plugins/platform/src/main/java/org/rhq/plugins/platform/FileSystemComponent.java;h=9d68c239f3bd981cfeee41f6b40e9ca5b28c6b4c;hb=HEAD#l73
[2]: http://git.fedorahosted.org/git?p=rhq/rhq.git;a=blob;f=modules/core/native-system/src/main/java/org/rhq/core/system/FileSystemInfo.java;h=2bde8ee772e6e1cb9af65b75dc5f4713c7c38c52;hb=HEAD#l46

--- Additional comment from ian.springer on 2011-11-11 10:43:53 EST ---

Nice find.

Fixed in master - commit 68be8c6:

http://git.fedorahosted.org/git/?p=rhq/rhq.git;a=commitdiff;h=68be8c6

--- Additional comment from loleary on 2011-11-11 10:54:24 EST ---

Upon further investigation the multiple executions actually result in invalid data coming back from the native library. The statistics that are gathered are time based with a time resolution of 1 second and some of the values are calculated based on the last "gather" time. If the refresh method is called in succession with a second or less between, the result is disk stats being calculated with:

 0.0 / 0 = NaN
 > 0.0 / 0 = Infinity

The result depends on the execution time.

Disk Queue test with delay of 0 returned 100 NaN results and 0 infinity results out of a total tests of 100
Disk Queue test with delay of 1 returned 100 NaN results and 0 infinity results out of a total tests of 100
Disk Queue test with delay of 5 returned 68 NaN results and 32 infinity results out of a total tests of 100
Disk Queue test with delay of 10 returned 70 NaN results and 29 infinity results out of a total tests of 100
Disk Queue test with delay of 50 returned 64 NaN results and 31 infinity results out of a total tests of 100
Disk Queue test with delay of 100 returned 51 NaN results and 39 infinity results out of a total tests of 100
Disk Queue test with delay of 500 returned 34 NaN results and 16 infinity results out of a total tests of 100
Disk Queue test with delay of 1000 returned 0 NaN results and 0 infinity results out of a total tests of 100
Disk Queue test with delay of 1001 returned 0 NaN results and 0 infinity results out of a total tests of 100
Disk Queue test with delay of 1010 returned 0 NaN results and 0 infinity results out of a total tests of 100
Disk Queue test with delay of 1050 returned 0 NaN results and 0 infinity results out of a total tests of 100
Disk Queue test with delay of 1100 returned 0 NaN results and 0 infinity results out of a total tests of 100
Disk Queue test with delay of 1500 returned 0 NaN results and 0 infinity results out of a total tests of 100
Disk Queue test with delay of 2000 returned 0 NaN results and 0 infinity results out of a total tests of 100

--- Additional comment from loleary on 2011-11-14 14:25:39 EST ---

Committed to release-3.0.1 as 96b03ecc9c77bd80e72792fd996b3a0ad6592229 - http://git.fedorahosted.org/git/?p=rhq/rhq.git;a=commitdiff;h=96b03ecc9c77bd80e72792fd996b3a0ad6592229

--- Additional comment from lkrejci on 2011-12-21 15:41:03 EST ---

Larry, would you be able to provide repro steps for this issue?

--- Additional comment from loleary on 2011-12-21 23:43:19 EST ---

1. From a Linux Platform resource, expand and select File System -> /boot
2. Select the Monitor > Tables sub-tab
3. The Last value for Disk Queue should contain a number

Actual Result:
<no value / i.e. it is blank>

Expected Result:
0 or a positive number

Please note that by default this metric is collected once every 20 minutes. So, if you are tested a new installation, it is best to drop the collection schedule for this metric to 1 minute so you do not have as long to wait.