Re: [jetty-dev] Resource leak with URLResource?

[Jens Reimann <jens.reimann@xxxxxxxxxxxxxxx>]

Hello Jan,

thanks for looking into this.

However I am not talking about JVM or Jetty caches. The Resource base
class does provide a few methods, like the "exists" check. For Resource
there are a few implementations, such as URLResource, which does perform
the "exists" check by opening the stream. Now if the URL is backed by a
file, due to some URL handler implementing the stream based on a file
resource, then the InputStream might be a FileInputStream, with a file
handle.

Now in this case the method checks for existence of the Resource, (which
creates a stream), but never calls close. So the stream will not get
closed. This might be ok for some stream types, although I doubt that,
but for a file stream, this will keep the file handle open.

So I think that either each resource must be closed properly, or the
check should not be allowed to cache the InputStream.

Thanks for creating the bug in bugzilla.

Jens

On 04/30/2015 12:33 AM, Jan Bartel wrote:
> Hi Jens,
>
> The jvm can cache URL connections, such as JarUrlConnections and also
> JarFile entries. By default, caching is enabled.  So, even if the
> Resource was closed, because caching is enabled, the jvm will still
> hold onto a reference to your url connection. You can try calling
> Resource.setDefaultUseCaches(false) to disable caching, and you should
> see that even without an explicit close, garbage collection should
> eventually get rid of the URL connection/JarFile entries etc.
>
> That said, I've opened an issue to look at any places in the code such
> as this that we could call Resource.close():
> https://bugs.eclipse.org/bugs/show_bug.cgi?id=465864
>
> Jan
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