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https://issues.apache.org/jira/browse/HADOOP-13726?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15970374#comment-15970374
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Manjunath Anand commented on HADOOP-13726:
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Thanks [~cnauroth] for your inputs. I uploaded the patch for trunk as per the
discussion in earlier comments. Although no explicit synchronization is done in
the Callable while creating the FileSystem, there is no
ConcurrentModificationException possibility due to the guava LocalCache
implementing java ConcurrentMap.
> Enforce that FileSystem initializes only a single instance of the requested
> FileSystem.
> ---------------------------------------------------------------------------------------
>
> Key: HADOOP-13726
> URL: https://issues.apache.org/jira/browse/HADOOP-13726
> Project: Hadoop Common
> Issue Type: Improvement
> Components: fs
> Reporter: Chris Nauroth
> Assignee: Manjunath Anand
> Attachments: HADOOP-13726.001.patch
>
>
> The {{FileSystem}} cache is intended to guarantee reuse of instances by
> multiple call sites or multiple threads. The current implementation does
> provide this guarantee, but there is a brief race condition window during
> which multiple threads could perform redundant initialization. If the file
> system implementation has expensive initialization logic, then this is
> wasteful. This issue proposes to eliminate that race condition and guarantee
> initialization of only a single instance.
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