Re: Relieving some ClassLoader contention in PreferredClassProvider

Gregg Wonderly <[email protected]>
Newsgroups gmane.comp.java.sun.jini
Message-ID <[email protected]>
Peter Jones wrote:
> On Thu, Jan 04, 2007 at 04:56:41PM -0600, Gregg Wonderly wrote:
>
>>Peter Jones wrote:
>>
>>
>>>Just to be clear, is the network activity that you are concerned about
>>>only the name->address resolution done by SocketPermission.implies
>>>during PreferredClassProvider.createClassLoader?  Or is it also the
>>>resolution potentially done by URL.equals during the table lookup and
>>>the "boomerang" search (PreferredClassProvider.findOriginLoader)?
>>
>>I am interested in acceptable behavior in both cases.  The
>>.implies() is one thing that causes all URLs to be queried (one
>>optimization I added was to check for an HttpURLConnection instance
>>and request a "HEAD" instead of "GET").  A non operating codebase
>>host, will hang all threads for at least the TCP timeout period
>>foreach URL.openConnection() at least.  So, I am really concerned
>>overall about minimizing the impact any particular failure has on
>>unrelated threads.
>
> Wait, are you suggesting that an actual HTTP request is attempted
> during the process of getting the permission for each codebase URL?

Yes, my vhttp handler serves streams from multiple possible locations (cache or
net) and its returns from openConnection() either a file: URL openConnection()
value or a deferred http: URL openConnection() value.

This is a detail associated with my implementation of that handler.

Gregg Wonderly

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