[jira] Closed: (DROIDS-68) HandlerFactory fails with multithreaded implementation

["Thorsten Scherler (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DROIDS-68?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Thorsten Scherler closed DROIDS-68.
-----------------------------------

    Resolution: Fixed

Committed revision 892828.

thanks Javier

> HandlerFactory fails with multithreaded implementation
> ------------------------------------------------------
>
>                 Key: DROIDS-68
>                 URL: https://issues.apache.org/jira/browse/DROIDS-68
>             Project: Droids
>          Issue Type: Bug
>          Components: core
>         Environment: Ubuntu 9.04 i386
> Java Runtime 1.6_16
>            Reporter: Javier Puerto
>            Priority: Critical
>         Attachments: droids_concurrency.patch, droidsTest_concurrency.patch
>
>
> Hi, I'm working with Droids and made some URL crawlers to save a lot of web pages in disk. In JUnit test, I run a little http server and crawl 20 pages, the most times everything works ok but in rare cases I get an error. I found the problem in the HandlerFactory implementation, in the example the call to handlers is like this:
> protected void handle(ContentEntity entity, Link link)
>     throws DroidsException, IOException
> {
>   droid.getHandlerFactory().handle(link.getURI(), entity);
> }
> If two or more workers is trying to handle at same time, the HandlerFactory will handle with the same instance. The solution could be saving memory or improving performance.
> The first solution could be implemented adding a "synchronized" to HandlerFactory.handle like this.
> public synchronized boolean handle(URI uri, ContentEntity entity)
>     throws DroidsException, IOException {
>   for (Handler handler : getMap().values()) {
>     handler.handle(uri, entity);
>   }
>   return true;
> }
> This solution works but it is a workaround.
> The real solution was discussed in the dev list and it was make the Droid and the GenericFactory abstractions clonable and invoking the clone method in the Worker's constructor.

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