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From "Felix Meschberger (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FELIX-5394) Memoryusage plugin creates a heap dump on every notification
Date Fri, 04 Nov 2016 19:28:59 GMT

    [ https://issues.apache.org/jira/browse/FELIX-5394?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15637414#comment-15637414
] 

Felix Meschberger commented on FELIX-5394:
------------------------------------------

bq. could you just clarify who will be responsible for setting the threshold on the memory
pool? will the plugin not set it any more going forward?

If the threshold is configured to zero, yes, the idea is that the plugin will not set it any
longer. If the configured value is in the valid range, the plugin will set it.

bq. also, might I add a small thing to your list: if the plugin is registered for a specific
threshold and it receives an event, it should check that the memory delta is within that threshold
before creating the dump

I am a bit at unease at doing that. My assumption is that someone enabled dumping by threshold.
Now someone else changed the threshold, but still the dump might be desired....

> Memoryusage plugin creates a heap dump on every notification
> ------------------------------------------------------------
>
>                 Key: FELIX-5394
>                 URL: https://issues.apache.org/jira/browse/FELIX-5394
>             Project: Felix
>          Issue Type: Bug
>          Components: Web Console
>    Affects Versions: webconsole-memoryusage-plugin-1.0.6
>            Reporter: Alex Parvulescu
>              Labels: patch-available
>         Attachments: FELIX-5394-v0.patch
>
>
> As a part of OAK-4966 I'm trying to install a listener on available memory with a notification
when a certain available memory threshold is met [0]. This seems to clash a bit with the current
{{memoryusage}} plugin, as both jmx listeners try to change the threshold for the notification,
and subsequently both might receive the notification at a different value than expected. (for
example I'm setting a notification at {{15%}} and even though the {{memoryusage}} plugin is
not used and is currently set at {{0%}} it will still create a heap dump:
> {noformat}
> *WARN* [Service Thread] org.apache.felix.webconsole.plugins.memoryusage Received Memory
Threshold Exceeded Notification, dumping Heap
> {noformat}
> I have 2 suggestions:
> * first is to _not_ change the threshold value if it's already set at a smaller value.
this means the plugin will not break other listeners expectations of receiving an event
>  
> * second is to verify the locally set threshold value against the values seen at notification
time. this effectively means the plugin is free to ignore certain events, and not dump the
heap to disk every time it gets a ping [1].
> I would like to provide a patch for this issue pretty soon as I really need to fix OAK-4966,
unless someone is more eager to come up with a working solution.
> [0] https://issues.apache.org/jira/browse/OAK-4966?focusedCommentId=15629253&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15629253
> [1] https://github.com/apache/felix/blob/trunk/webconsole-plugins/memoryusage/src/main/java/org/apache/felix/webconsole/plugins/memoryusage/internal/MemoryUsageSupport.java#L553



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