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Date: Wed, 23 Aug 2017 17:40:00 +0000 (UTC)
From: "Bernd Eckenfels (JIRA)" <jira@apache.org>
To: issues@commons.apache.org
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Subject: [jira] [Commented] (VFS-640) Synchronized
 AbstractOriginatingFileProvider.getFileSystem is too broad
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archived-at: Wed, 23 Aug 2017 17:40:06 -0000


    [ https://issues.apache.org/jira/browse/VFS-640?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16138728#comment-16138728 ] 

Bernd Eckenfels commented on VFS-640:
-------------------------------------

One option would be to avoid slow server connections in the createFilesystem. A more general solution could be having a lock keyed by serverendpoint.

> Synchronized AbstractOriginatingFileProvider.getFileSystem is too broad
> -----------------------------------------------------------------------
>
>                 Key: VFS-640
>                 URL: https://issues.apache.org/jira/browse/VFS-640
>             Project: Commons VFS
>          Issue Type: Bug
>    Affects Versions: 2.0, 2.1
>            Reporter: L
>
> Currently (rev. 1802455) this method looks like this:
> {code:java}
>     protected synchronized FileSystem getFileSystem(final FileName rootName, final FileSystemOptions fileSystemOptions)
>         throws FileSystemException
>     {
>         FileSystem fs = findFileSystem(rootName, fileSystemOptions);
>         if (fs == null)
>         {
>             // Need to create the file system, and cache it
>             fs = doCreateFileSystem(rootName, fileSystemOptions);
>             addFileSystem(rootName, fs);
>         }
>         return fs;
>     }
> {code}
> Given that there is a single instance of a provider per scheme, a very slow server that is being accessed first time will block *all* other threads trying to access some other resources via the same provider.
> We have a server that takes sometimes 20-30 seconds in doCreateFileSystem. We do not mind the thread trying to access this method taking that long, but because of that "synchronized" we end up having multiple threads accessing unrelated servers for the same scheme blocked.
> PS. Actually, it is not only AbstractOriginatingFileProvider. The same "provider-scoped" lock is present in AbstractLayeredFileProvider, TemporaryFileProvider, and UrlFileProvider


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