Re: [openj9-dev] OpenJ9 question

[akrus <akrus@xxxxxxxxxxx>]

Hi Daniel,

Thanks for your response, created an issue regarding JMX:

https://github.com/eclipse/openj9/issues/629

On 20/11/17 17:48, Daniel Heidinga wrote:

Hi Akrus,

 

We're here though we've been (too) quiet on the list.  Regarding IRC or similar chat channel, I've opened https://github.com/eclipse/openj9/issues/627 to discuss where to create a channel.

 

> 1) does OpenJ9 support JMX for monitoring purposes? I've tried to enable them the same way as Oracle's one, but it doesn't listen on a port.

 

OpenJ9 should support JMX as its being tested regularly in the builds [1].  Have you set a port using an option like '-Dcom.sun.management.jmxremote.port=9999'?  If that doesn't solve it, please open an issue on GitHub so we can help dig into this with you.  Test cases, command lines, etc would help.

 

> 4) is it possible to list the available flags? Documentation is quite limited, I wasn't able to find out a comprehensive list with descriptions.

 

The full set of options haven't been documented at the OpenJ9 project yet.  Most of the documentation for IBM's JDK still applies

https://www.ibm.com/support/knowledgecenter/en/SSYKE2_8.0.0/com.ibm.java.aix.80.doc/diag/appendixes/cmdline/commands_jvm.html

https://www.ibm.com/support/knowledgecenter/SSYKE2_8.0.0/com.ibm.java.aix.80.doc/diag/appendixes/cmdline/commands_gc.html

 

I'll let some of the GC devs respond to questions around which policy to pick and how to rotate the logs.

 

--Dan

 

[1] https://ci.eclipse.org/openj9/view/Test/job/Test-Sanity-linux_390-64_cmprssptrs/lastCompletedBuild/testReport/org.openj9.test.java.lang.management/

 

 

----- Original message -----
From: akrus <akrus@xxxxxxxxxxx>
Sent by: openj9-dev-bounces@xxxxxxxxxxx
To: openj9-dev@xxxxxxxxxxx
Cc:
Subject: [openj9-dev] OpenJ9 question
Date: Mon, Nov 20, 2017 5:50 AM
 

Hello everyone! (if somebody is here)

I have several questions related to OpenJ9, but apart from Github issues and this mailing list I wasn't able to find another place to ask.

1) does OpenJ9 support JMX for monitoring purposes? I've tried to enable them the same way as Oracle's one, but it doesn't listen on a port.
2) with -Xgcpolicy:metronome and heap >25Gb I get this message:
Selected VM [default] does not exist.
Is it expected behavior? Metronome GC doesn't support heaps larger than 25Gb?
3) what's the best GC option for low latency apps? Does do not say this directly, but is it Metronome? Are there any flags than can further reduce GC pauses? -Xrealtime doesn't work, is it unavailable completely or it's a part of some subscription?
4) is it possible to list the available flags? Documentation is quite limited, I wasn't able to find out a comprehensive list with descriptions.
5) how to rotate GC logs? are the flags -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=100 -XX:GCLogFileSize=100M supported? Does OpenJ9 accept a signal to flush the logs?

Thanks in advance.

Btw, is there any IRC chat or something similar available for general questions?

Regards,
akrus.

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