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From Arpit Agarwal <aagar...@hortonworks.com>
Subject Re: Is FileSystem thread-safe?
Date Mon, 01 Apr 2013 22:17:39 GMT
Hi John,

DistributedFileSystem is intended to be thread-safe, true to its name.

Metadata operations are handled by the NameNode server which synchronizes
concurrent client requests via locks (you can look at the FSNameSystem
class).

Some discussion on the thread-safety aspects of HDFS:
http://storageconference.org/2010/Papers/MSST/Shvachko.pdf

-Arpit


On Sun, Mar 31, 2013 at 11:52 AM, Ted Yu <yuzhihong@gmail.com> wrote:

> If you look at DistributedFileSystem source code, you would see that it
> calls the DFSClient field member for most of the actions.
> Requests to Namenode are then made through ClientProtocol.
>
> An hdfs committer would be able to give you affirmative answer.
>
>
> On Sun, Mar 31, 2013 at 11:27 AM, John Lilley <john.lilley@redpoint.net>wrote:
>
>>  *From:* Ted Yu [mailto:yuzhihong@gmail.com]
>> *Subject:* Re: Is FileSystem thread-safe?****
>>
>> >>FileSystem is an abstract class, what concrete class are you using
>> (DistributedFileSystem, etc) ? ****
>>
>> Good point.  I am calling FileSystem.get(URI uri, Configuration conf)
>> with an URI like “hdfs://server:port/…” on a remote server, so I assume it
>> is creating a DistributedFileSystem.  However I am not finding any
>> documentation discussing its thread-safety (or lack thereof), perhaps you
>> can point me to it?****
>>
>> Thanks, john****
>>
>
>

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