[jira] Reopened: (SMXCOMP-713) Threading problem in Servicemix-HTTP which renders the component unusable.

["Ryan Moquin (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/activemq/browse/SMXCOMP-713?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ryan Moquin reopened SMXCOMP-713:
---------------------------------


Hi Jean,

I looked at what you commited to the source repository.  Could you verify that you also made the changes in the revised patch that I posted?  It didn't look like you did and if you don't, then a problem will occur with the servicemix-http component if the exchange is sent via JMS flow.  If that change is in there then great.  I've been using that second patch for quite a while now and everything has been rock solid with no issues since.

BTW - that second patch only includes one extra line to attach the exchange received to the continuation (this way if the exchange did change as a result of going over jmsflow, when you replay the request, the correct exchange will be used).

If you did use that second patch, I apologize.  When I looked at the code it didn't look like it was included.

Thanks!!

Ryan

> Threading problem in Servicemix-HTTP which renders the component unusable.
> --------------------------------------------------------------------------
>
>                 Key: SMXCOMP-713
>                 URL: https://issues.apache.org/activemq/browse/SMXCOMP-713
>             Project: ServiceMix Components
>          Issue Type: Bug
>          Components: servicemix-http
>    Affects Versions: servicemix-http-2008.01, servicemix-http-2009.01, servicemix-http-2009.02
>         Environment: Windows XP, servicemix-http component 2009.02
>            Reporter: Ryan Moquin
>            Assignee: Jean-Baptiste Onofré
>            Priority: Blocker
>             Fix For: servicemix-http-2010.01
>
>         Attachments: HttpConsumerEndpoint.java, HttpConsumerEndpoint.java
>
>
> In most of the servicemix-http component versions, including the latest, there is a variable called isSTFlow which is a class variable.  This variable appears to be shared among all threads that access a deployed servicemix-http component.  The problem with this is that isSTFlow is set by a certain request based upon the state of it's continuation when the exchange response is processed here:
> if (!cont.isPending()) {
>             isSTFlow = true;
>             System.out.println("isSTFlow set to true because continuation isn't pending.");
>         } else {
>             isSTFlow = false;
>             System.out.println("isSTFlow set to false because continuation is pending.");
> If isSTFlow is set to true during that response.. all future requests that come in will then end up executing this code block on line 348:
> } else {
>                         String id = (String)request.getAttribute(MessageExchange.class.getName());
>                         System.out.println("STFlow was true, removing exchange with id: " + id);
>                         locks.remove(id);
>                         exchange = exchanges.remove(id);
>                         request.removeAttribute(MessageExchange.class.getName());
>                     }
> before the exchange associated with the request has had a chance to return.  Once that exchange has returned, it can't be found, because it was removed and throws a timeout error.  Once isSTFlow becomes true, the component hits a race condition where it checks isSTFlow for true before the async call has a chance to return and immediately times out the exchange.  This variable needs to be localized for each specific request, not global to all requests.

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