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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CURATOR-106) Issuing a guaranteed delete can cause stack overflow if ZK is not reachable
Date Sun, 28 May 2017 17:23:04 GMT

    [ https://issues.apache.org/jira/browse/CURATOR-106?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16027869#comment-16027869
] 

ASF GitHub Bot commented on CURATOR-106:
----------------------------------------

Github user srdo commented on the issue:

    https://github.com/apache/curator/pull/215
  
    @Randgalt Could you elaborate on why this is wrong? If I understand you, the issue is
that background callbacks must happen in the Zookeeper thread, not CuratorFrameworkImpl's
ExecutorService thread? I still don't see how this is changed by the code you posted. In order
for there to be a change in behavior, a Zookeeper thread must call `CuratorFrameworkImpl.processBackgroundOperation`
with a null event. If the event is not null, the behavior is unchanged.
    
    I'm having a hard time finding any instances of `CuratorFrameworkImpl.processBackgroundOperation`
being called with a null event from a Zookeeper callback. The calls I can find all have a
non-null event when called from inside a Zookeeper callback.
    
    It looks to me like all the calls to `processBackgroundOperation` with a null event are
coming from `forPath` or equivalent (e.g. `forOperations`). Aren't those running in the user's
thread, and not one of Zookeeper's threads?
    
    Do you have an example where the thread executing the background callback has changed,
or any calls to `processBackgroundOperation` with a null event from Zookeeper callback code?


> Issuing a guaranteed delete can cause stack overflow if ZK is not reachable
> ---------------------------------------------------------------------------
>
>                 Key: CURATOR-106
>                 URL: https://issues.apache.org/jira/browse/CURATOR-106
>             Project: Apache Curator
>          Issue Type: Bug
>          Components: Framework
>    Affects Versions: 2.4.2
>            Reporter: Jasdeep Hundal
>             Fix For: awaiting-response
>
>
> For guaranteed deletes (eg. lock releases) that fail, the FailedDeleteManager issues
another guaranteed delete here:
> https://github.com/apache/curator/blob/master/curator-framework/src/main/java/org/apache/curator/framework/imps/FailedDeleteManager.java#L35
> In an environment where ZK has the potential to be down for an extended period of time,
this has the potential to recurse until there is a stack overflow (particularly if the application
is using multiple locks.)



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