Hi dtranter
Please specify the plugin version.

It seems like a missing bounds check in https://github.com/javamelody/javamelody/blob/master/javamelody-core/src/main/java/net/bull/javamelody/RrdNioBackend.java#L146-L149 . The underlying buffer management code is http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/java/nio/Buffer.java#235 , so there's only one way to get this exception.

Follow-up issue in JavaMelody project: https://github.com/javamelody/javamelody/issues/533

Yes, what is the plugin version?

And also can you copy here the "debugging logs" which are displayed at the botton of the /monitoring page? Thanks

We'll have to get back to you on the logs, but the version was 1.57 at the time the problem was initially raised. It has now been updated to 1.58.

Upon update from 1.57 -> 1.58 and restart, monitoring graphs are now displaying again.. However I'm still seeing warnings/exception collecting data, unsure if that's related to previous failure. Unfortunately the current debugging log no longer contains entries from the time of failure:

Last collect time: 861 ms
Display time: 678 ms
Memory overhead estimate: < 5 Mb
Disk usage: 39 Mb Purge the obsolete files

JavaMelody 1.58.0
Debugging logs

Only the last 50 messages are displayed
Fri Feb 19 20:07:12 CST 2016 DEBUG Server: jetty/winstone-2.8
Fri Feb 19 20:07:12 CST 2016 DEBUG Webapp context:
Fri Feb 19 20:07:12 CST 2016 DEBUG JavaMelody version: 1.58.0
Fri Feb 19 20:07:12 CST 2016 DEBUG JavaMelody classes loaded from: file:/auto/ncs-jenkins/ncs-jenkins/jenkins/plugins/monitoring/WEB-INF/lib/javamelody-core-1.58.0.jar
Fri Feb 19 20:07:12 CST 2016 DEBUG Host: host5@123.123.123.123
Fri Feb 19 20:07:12 CST 2016 DEBUG parameter defined: storage-directory=//auto/ncs-jenkins/ncs-jenkins/jenkins/monitoring
Fri Feb 19 20:07:12 CST 2016 DEBUG parameter defined: http-transform-pattern=/\d+/|/site/.|avadoc/.|/ws/.|obertura/.|estReport/.|iolations/file/.|/user/.|/static/\w/|/adjuncts/\w+/|/bound/[\w\-]+
Fri Feb 19 20:07:12 CST 2016 DEBUG parameter defined: custom-reports=Jenkins Info,About Monitoring
Fri Feb 19 20:07:12 CST 2016 DEBUG parameter defined: no-database=true
Fri Feb 19 20:07:12 CST 2016 DEBUG parameter defined: gzip-compression-disabled=true
Fri Feb 19 20:07:12 CST 2016 DEBUG parameter defined: system-actions-enabled=true
Fri Feb 19 20:07:12 CST 2016 DEBUG log listeners initialized
Fri Feb 19 20:07:12 CST 2016 DEBUG counters initialized
Fri Feb 19 20:07:12 CST 2016 DEBUG counters data read from files in /auto/ncs-jenkins/ncs-jenkins/jenkins/monitoring/_host5
Fri Feb 19 20:07:12 CST 2016 DEBUG collect task scheduled every 60s
Fri Feb 19 20:07:13 CST 2016 DEBUG first collect of data done
Fri Feb 19 20:07:13 CST 2016 DEBUG JavaMelody filter init done in 308 ms
Fri Feb 19 20:07:13 CST 2016 DEBUG counters data read from files in /auto/ncs-jenkins/ncs-jenkins/jenkins/monitoring/nodes
Sat Feb 20 00:00:29 CST 2016 DEBUG Obsolete files deleted. JavaMelody disk usage: 14327 KB
Sat Feb 20 00:00:32 CST 2016 DEBUG Obsolete files deleted. JavaMelody disk usage: 134286 KB
Sun Feb 21 00:00:35 CST 2016 DEBUG Obsolete files deleted. JavaMelody disk usage: 27464 KB
Sun Feb 21 00:00:39 CST 2016 DEBUG Obsolete files deleted. JavaMelody disk usage: 130530 KB
Sun Feb 21 07:02:36 CST 2016 WARN exception while collecting data
Sun Feb 21 07:03:36 CST 2016 WARN exception while collecting data
Sun Feb 21 07:04:36 CST 2016 WARN exception while collecting data
Sun Feb 21 07:05:36 CST 2016 WARN exception while collecting data
Sun Feb 21 07:06:36 CST 2016 WARN exception while collecting data
Sun Feb 21 07:07:36 CST 2016 WARN exception while collecting data
Sun Feb 21 07:08:36 CST 2016 WARN exception while collecting data
Sun Feb 21 07:09:36 CST 2016 WARN exception while collecting data
Sun Feb 21 07:10:36 CST 2016 WARN exception while collecting data
Sun Feb 21 07:11:36 CST 2016 WARN exception while collecting data
Sun Feb 21 07:12:36 CST 2016 WARN exception while collecting data
Sun Feb 21 07:13:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:21:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:22:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:23:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:24:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:25:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:26:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:27:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:28:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:29:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:30:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:31:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:32:36 CST 2016 WARN exception while collecting data
Sun Feb 21 08:33:36 CST 2016 WARN exception while collecting data
Mon Feb 22 00:00:36 CST 2016 DEBUG Obsolete files deleted. JavaMelody disk usage: 39034 KB
Mon Feb 22 00:00:43 CST 2016 DEBUG Obsolete files deleted. JavaMelody disk usage: 130487 KB
Mon Feb 22 03:37:38 CST 2016 WARN exception while collecting data

Thanks,

I think that a file in the storage directories (/auto/ncs-jenkins/ncs-jenkins/jenkins/monitoring/**) was corrupted somewhere in the middle of the file. And that javamelody / jrobin can't read it anymore.

You can try to find if ".rrd" file(s) in the storage directories do not have the same size as the others and to delete it.
But what is strange is that corruption seems intermittent: from 7:02 to 7:13 and from 8:21 to 8:33 but nothing the day before.

Anyway, I have added a catch in the code to auto-reset the file in this case. (2eff216)
And 1.59 release is planned soon including that fix.