missing max FD count?

[admini]

http://java-monitor.com/postedimages/c58aaa1d-8b35-4ba5-bb3f-99b5b3147270.png

Hi java mon guru('s),

I have been known to be blind as a bat, but still, am I missing the max file descriptors in this graph? As long as I have your attention, is this a running max. or an OS/JDK determined max?

What about the open descriptor graph... does it look like "normal" behavior to y'all? I find those major steps a bit strange.

Cheers, Leon (aka admini).

[admini]

The shape of the FD's seem to relate to the threads graph. See the attached pics.

Cheers, Leon.

[kjkoster]

Uploaded the attachment for admini

[kjkoster]

Dear Leon,

To answer the first question: that is a bug in the graph generating code of Java-monitor. The max is not shown properly. You can see the max in the JMX details page for your host. The link is on the host page, search for the text "see all measurements".

To answer your second question: if this is not a restart, this looks like some threads went from Runnable to Waiting.

Please note that "Runnable" is not just runnable in the UNIX process runnable sense. It also includes threads that are waiting for network requests to be accepted. Why that is, I don't know.

My guess (and it is only a guess) is that some threads accepted and handled requests and then slowly were put back into the accepting/runnable state. You'll have to dig a little deeper to find more, I am afraid.

What you can do is take periodic stack dumps to see what is going on in more detail.

Is there any strange behaviour on this server that may tell you more about what is happening? Errors in the logs?

Kees Jan

[admini]

Hi Kees Jan and all other interested admins,

Thanks for your info, especially about the meaning of the Java interpretation of Runnable. I didn't know that.

I looked at the logs of the system, but found no anomaly whatsoever, no Exceptions of any kind. The system was very lightly loaded, apparently by a Google bot:

<httpheader name="user-agent">Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)</httpheader>

Well, I think I'll postpone trying to understand more of the meaning of the graphs when something interesting is happening inside my managed systems.

Leon.
NB. I like java-monitor calling me a "Junior Member". That's good for my ego. Most people find me uhm.... geriatrically challenged ;)