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From "Kim Jaechang (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CURATOR-527) Concurrency issue in LockInternals
Date Wed, 05 Jun 2019 16:07:01 GMT

     [ https://issues.apache.org/jira/browse/CURATOR-527?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Kim Jaechang updated CURATOR-527:
---------------------------------
    Description: 
I'm using InterProcessMutex and InterProcessMutex often failed to acquire lock.

In LockInternals.internalLockLoop(), watcher is registered to zookeeper and call wait() like
below
{code:java}
client.getData().usingWatcher(watcher).forPath(previousSequencePath);
if ( millisToWait != null )
{
    millisToWait -= (System.currentTimeMillis() - startMillis);
    startMillis = System.currentTimeMillis();
    if ( millisToWait <= 0 )
    {
        doDelete = true;    // timed out - delete our node
        break;
    }

    wait(millisToWait);
}
else
{
    wait();
}
{code}
In my case, my program is waiting previousSequencePath=_c_f290140d-9856-42ad-b9bf-348ffc086062-lock-0000000759
to be deleted.

But _c_f290140d-9856-42ad-b9bf-348ffc086062-lock-0000000759 is deleted between client.getData()
and wait().

if _c_f290140d-9856-42ad-b9bf-348ffc086062-lock-0000000759 is deleted when 
client.getData().usingWatcher(watcher).forPath(previousSequencePath) is called, it will throw
Exception but it was exist at that time.

I'm using Curator 2.12.0 but latest version seems to have same issue.

  was:
I'm using InterProcessMutex and InterProcessMutex often failed to acquire lock.

In LockInternals.internalLockLoop(), watcher is registered to zookeeper and call wait() like
below
{code:java}
client.getData().usingWatcher(watcher).forPath(previousSequencePath);
if ( millisToWait != null )
{
    millisToWait -= (System.currentTimeMillis() - startMillis);
    startMillis = System.currentTimeMillis();
    if ( millisToWait <= 0 )
    {
        doDelete = true;    // timed out - delete our node
        break;
    }

    wait(millisToWait);
}
else
{
    wait();
}
{code}
In my case, my program is waiting previousSequencePath=_c_50f10103-c19e-45f4-8cc3-ba686ea452fe-lock-0000000760
to be deleted.

But _c_50f10103-c19e-45f4-8cc3-ba686ea452fe-lock-0000000760 is deleted between client.getData()
and wait().

if _c_50f10103-c19e-45f4-8cc3-ba686ea452fe-lock-0000000760 is deleted when 
client.getData().usingWatcher(watcher).forPath(previousSequencePath) is called, it will throw
Exception but it was exist at that time.

I'm using Curator 2.12.0 but latest version seems to have same issue.


> Concurrency issue in LockInternals
> ----------------------------------
>
>                 Key: CURATOR-527
>                 URL: https://issues.apache.org/jira/browse/CURATOR-527
>             Project: Apache Curator
>          Issue Type: Bug
>          Components: Recipes
>    Affects Versions: 2.12.0
>         Environment: Curator 2.12.0
> zookeeper 3.4.14
>            Reporter: Kim Jaechang
>            Priority: Major
>
> I'm using InterProcessMutex and InterProcessMutex often failed to acquire lock.
> In LockInternals.internalLockLoop(), watcher is registered to zookeeper and call wait()
like below
> {code:java}
> client.getData().usingWatcher(watcher).forPath(previousSequencePath);
> if ( millisToWait != null )
> {
>     millisToWait -= (System.currentTimeMillis() - startMillis);
>     startMillis = System.currentTimeMillis();
>     if ( millisToWait <= 0 )
>     {
>         doDelete = true;    // timed out - delete our node
>         break;
>     }
>     wait(millisToWait);
> }
> else
> {
>     wait();
> }
> {code}
> In my case, my program is waiting previousSequencePath=_c_f290140d-9856-42ad-b9bf-348ffc086062-lock-0000000759
to be deleted.
> But _c_f290140d-9856-42ad-b9bf-348ffc086062-lock-0000000759 is deleted between client.getData()
and wait().
> if _c_f290140d-9856-42ad-b9bf-348ffc086062-lock-0000000759 is deleted when 
> client.getData().usingWatcher(watcher).forPath(previousSequencePath) is called, it will
throw Exception but it was exist at that time.
> I'm using Curator 2.12.0 but latest version seems to have same issue.



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