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Re: FSFS corrupted revfiles && APR minimal version?

From: John Szakmeister <john_at_szakmeister.net>
Date: 2007-11-07 10:27:04 CET

Erik Huelsmann wrote:
> I just checked the APR site and the latest versions are 1.2.11 and
> 0.9.16. While checking their CHANGES files (respectively at
> http://www.apache.org/dist/apr/CHANGES-APR-1.2 and
> http://www.apache.org/dist/apr/CHANGES-APR-0.9), I noticed that there
> are some fixes which are at least interesting for us. My question is:
> Could these be related to the FSFS revfile corruptions we have seen
> and if so, should we up our requirements?
>
> 1) "Fix file pointer position calculation in apr_file_writev()." (apr
> 0.9.14 and 1.2.9)
> 2) "Fix thread safety of assorted file_io functions" (apr 0.9.14 and 1.2.9)
>
>
> Does anybody have an answer to these questions?

I'm not sure I can really answer these questions, but I'll try.

1) apr_file_writev doesn't appear to be used by SVN (a least that's what
a quick grep has revealed).

2) I'm not sure these matter either.

The root of the problem seems to stem around the fact that a network
session can end (from some sort of error), but the associated pools
aren't cleared before the client retries. The end result is that the
client is able to start writing new data to the file (with a new file
object), and when the pool is finally cleaned up from the old session we
end up with a corrupted rev (because data is flushed into the file).

So the problem seems to be ours and not APR's.

-John

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Received on Wed Nov 7 10:27:39 2007

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