[jboss-jira] [JBoss JIRA] (WFLY-4617) Huge garbage created at regular intervals in Wildfly 8.2.0.Final

[Srivathsan Agaram Venkatavaradhan (JIRA)]

    [ https://issues.jboss.org/browse/WFLY-4617?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13066956#comment-13066956 ] 

Srivathsan Agaram Venkatavaradhan commented on WFLY-4617:
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There were few places in the app where request is set in ThreadLocal , some places where velocity context is not cleared. Tried to clear them now there is no reachable reference to the char array but still heap is increasing constantly and full gc happens every few mins. 
MAT image after the fix 
https://www.dropbox.com/s/of9ze2asehqgn7m/Incoming%20char%20array%20reference%20after%20fix.png?dl=0

MAT image before the fix 
https://www.dropbox.com/s/oke21sa6clygl1b/Char%20Array%20Incoming%20reference?dl=0

All images related to the issue:
https://www.dropbox.com/sh/qgsitzb7x27j8kc/AABoQwR1qPwTPiDtO6B0_Pm7a?dl=0 

Any thoughts on why gc is not able to cleanup as there is no active reference for the object. 



> Huge garbage created at regular intervals in Wildfly 8.2.0.Final
> ----------------------------------------------------------------
>
>                 Key: WFLY-4617
>                 URL: https://issues.jboss.org/browse/WFLY-4617
>             Project: WildFly
>          Issue Type: Bug
>    Affects Versions: 8.2.0.Final
>         Environment: Centos 7, JDK 7
>            Reporter: Srivathsan Agaram Venkatavaradhan
>            Assignee: Stuart Douglas
>              Labels: 8.2.0.Final, gc, undertow, wildfly
>         Attachments: Char Array Incoming reference, Char Array Retained Objects, Heap Histogram View, merge paths - ArtifactDetailList, newheap1_Leak_Suspects.zip, Overall Heap, Overall Memory Usages
>
>
> Huge garbage is created in wildfly every couple of minutes. Though Full GC is able to reclaim memory, this causes frequent full gcs, as heap is getting occupied due to the increase in number of objects created . We can reproduce this issue in 60 users Jmeter loadtest. This was not the case in Jboss 7.1.1Final. 
> After analyzing heapdumps,   Huge char arrays are created and they are not garbage collected by Minor GC.  Incoming reference for the char array suggest that they have valid reference to io.undertow.servlet.spec.HttpServletRequestImpl. However full gc is able to recover the memory. Not sure why attributes in  io.undertow.servlet.spec.HttpServletRequestImpl are not getting gced by minor gc's.
> "org.apache.struts.tiles.ComponentContext"  is kept in  attributes Map by io.undertow.servlet.spec.HttpServletRequestImpl.  org.apache.struts.tiles.ComponentContext contains a big char array.
> We suspect issue with undertow.



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