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Re: Problems with transaction file "next-ids" on Windows

From: Daniel Shahaf <d.s_at_daniel.shahaf.name>
Date: Wed, 20 Jul 2011 18:58:25 +0300

Philip Martin wrote on Wed, Jul 20, 2011 at 15:12:51 +0100:
> Daniel Shahaf <d.s_at_daniel.shahaf.name> writes:
>
> > Mathias Weinert wrote on Wed, Jul 20, 2011 at 14:59:23 +0200:
> >>
> >> each time when I am loading a certain dump file on Windows which
> >> contains one revision with over 100K changed paths I get the error
> >> "Can't open file
> >> 'c:\Repositories\test\db\transactions\5445-479.txn\next-ids': The
> >> requested operation cannot be performed on a file with a user-mapped
> >> section open.". After looking at the mailing list archives and other
> >> mailing lists I found out that I am not the only one to encounter
> >> this problem and that in most cases a virus scanner was the cause of
> >> the problem. And indeed, adding next-ids to the exclusion list
> >> solved the problem.
> >>
> >> But now I wonder if svnadmin couldn't handle this case a bit more
> >> elegantly. IMHO it would make sense not to quit the load immediately
> >> but to try it again maybe after waiting half a second or so if this
> >> specific error occurs (some other users reported that they got the
> >> error "The process cannot access the file because it is being used
> >> by another process."). If we can't access next-ids after trying it
> >> let's say 5 times with a little pause after each try we still can
> >> quit the load process.
> >
> > It would be good to solve this now as that is one of the concerns with
> > the (partially implemented) design for revprop packing, due for release
> > in 1.8.
>
> The current implementation writes the file inplace:
>
> static svn_error_t *
> write_next_ids(svn_fs_t *fs,
> const char *txn_id,
> const char *node_id,
> const char *copy_id,
> apr_pool_t *pool)
> {
> apr_file_t *file;
> svn_stream_t *out_stream;
>
> SVN_ERR(svn_io_file_open(&file, path_txn_next_ids(fs, txn_id, pool),
> APR_WRITE | APR_TRUNCATE,
> APR_OS_DEFAULT, pool));
>
> out_stream = svn_stream_from_aprfile2(file, TRUE, pool);
>
> SVN_ERR(svn_stream_printf(out_stream, pool, "%s %s\n", node_id, copy_id));
>
> SVN_ERR(svn_stream_close(out_stream));
> return svn_io_file_close(file, pool);
> }
>
> Is there any reason we don't switch to our standard pattern: write to a
> temp file and rename? That would give us Subversion's standard retry
> loop -- would that fix "requested operation cannot be performed"?

fs_fs.c:move_into_file() already does the rename loop, so no objection.
(assuming we document that the use of move_into_file() is for
performance and virus scanners rather than for concurrent reader
correctness)

>
> --
> uberSVN: Apache Subversion Made Easy
> http://www.uberSVN.com
Received on 2011-07-20 17:59:11 CEST

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