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From Todd Lipcon <t...@cloudera.com>
Subject Re: VOTE: HDFS-347 merge
Date Wed, 20 Feb 2013 23:13:50 GMT
On Wed, Feb 20, 2013 at 3:08 PM, Tsz Wo Sze <szetszwo@yahoo.com> wrote:
> The reason to keep it around is that the HDFS-347 only support Unix but not
> other OS.

Given that this is an optimization, and we have a ton of optimizations
which don't yet run on Windows, I don't think that should be
considered. Additionally, the Windows support has not yet been merged,
nor is it in any release, so this isn't a regression.

I would be happy to review an addition to the HDFS-347 branch which
addresses this issue. But I don't think we should be maintaining two
codepaths for the sake of an optimization on a platform which is not
yet officially supported on trunk, especially when the old code path
is _insecure_ and thus unusable in most environments.

Todd

>
> ________________________________
> From: Todd Lipcon <todd@cloudera.com>
> To: hdfs-dev@hadoop.apache.org; Tsz Wo Sze <szetszwo@yahoo.com>
> Sent: Wednesday, February 20, 2013 3:06 PM
>
> Subject: Re: VOTE: HDFS-347 merge
>
> On Wed, Feb 20, 2013 at 3:01 PM, Tsz Wo Sze <szetszwo@yahoo.com> wrote:
>> Also, the patch seems to have removed the existing short-circuit read
>> feature (HDFS-2246).  It is an incompatible change.  I think the patch is
>> farther away from being ready and I would keep my -1.
>
> The existing short circuit feature is insecure and was always
> considered a stop-gap solution. If you read the history of that
> feature, you can find comments like
> https://issues.apache.org/jira/browse/HDFS-4476 where I pointed out
> that it's only a stop-gap solution and the only reason I didn't veto
> is that folks agreed to later replace it with the proper solution
> (HDFS-347).
>
> Given that the API is the same, and this is an implementation detail,
> it is not incompatible. There is no reason to keep the old
> implementation around: it is both slower and unusable in the vast
> majority of clusters, where the data directories are owned by an HDFS
> user, and users of the cluster run under other unix credentials.
>
> -Todd
> --
> Todd Lipcon
> Software Engineer, Cloudera
>
>



-- 
Todd Lipcon
Software Engineer, Cloudera

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