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RE: svnadmin load errors on Windows (and .svn/tmp errors on svn cleanup)

From: Bob Kerns <Bob.Kerns_at_positscience.com>
Date: 2007-06-27 23:10:37 CEST

Well, the Compiler I have (the OrcaBeta1 of Visual Studio 9) doesn't
seem to be compatible.

But I have a different, but related problem, and what I *think* is a
solution. Unfortunately, since I can't build, I can't test....

Every time I try to do 'svn cleanup' on a working copy of our full tree
under Vista, it destroys my working copy. First it gets an "access
denied" trying to create .svn/tmp, and then it gets an error that the
.svn/tmp directory isn't there (since it couldn't create it).

The directory where it fails is non-deterministic -- a different one
every time. But over the size of my full tree, the odds of success for
all directories approach zero.

I have four observations, the fourth of which I believe is the cause of
this difficulty.

First obvservation: Revision 23370 claims to fix the error on missing
.svn/tmp, but doesn't seem to handle this case.
Revision 23370 - (view) (download) (annotate) - [select for diffs]
Modified Thu Feb 8 09:13:39 2007 UTC (4 months, 2 weeks ago) by lundblad
File length: 103631 byte(s)
Diff to previous 23341

Make 'svn cleanup' not fail on a missing .svn/tmp directory. It is
removed and rebuilt anyway so failing if it does not exist is

Patch by: Henner Zeller <h.zeller@acm.org>

* subversion/include/svn_io.h
  (svn_io_remove_dir2): New function. Add ignore_enoent flag.
  (svn_io_remove_dir): Deprecate. All callers updated to use

* subversion/libsvn_subr/io.c
  (svn_io_remove_dir2): Copy from svn_io_remove_dir, adding
  (svn_io_remove_dir): Wrap svn_io_remove_dir2.

* subversion/libsvn_wc/adm_files.c (svn_wc__adm_cleanup_tmp_area): Don't
  fail if the tmp directory doesn't exist.

* subversion/tests/cmdline/basic_tests.py
  (basic_cleanup): Add regression: missing tmp-dir in cleanup.

* subversion/tests/cmdline/svntest/actions.py
  (remove_admin_tmp_dir): New function.

Second obvservation:

The comment on WIN32_RETRY_LOOP doesn't really explain the situation
  Windows is 'aided' by a number of types of applications that
  follow other applications around and open up files they have
  changed for various reasons (the most intrusive are virus
  scanners). So, if one of these other apps has glommed onto
  our file we may get an 'access denied' error.

  This retry loop does not completely solve the problem (who
  knows how long the other app is going to hold onto it for), but
  goes a long way towards minimizing it. It is not an infinite
  loop because there might really be an error.

This is only one of the scenarios that can cause it to fail. The main
problem is that deleting is asynchronous. No virus scanners or other
applications are necessary to provoke the problem.

Third observation:

I think the number of iterations in WIN32_RETRY_LOOP should be
substantially increased, probably by a factor of 10. (That shouldn't be
necessary for handling the asynchronous deletes, but if it's virus
scanner, etc, it should really give it more time before concluding it's
not going to work).

Final, MAIN observation:

In this case, the problem (I believe) is in dir_make, which needs to use
  status = apr_dir_make(path_apr, perm, pool);
  WIN32_RETRY_LOOP(status, apr_dir_make(path_apr, perm, pool);

Probably also svn_io_make_dir_recursive:
  apr_err = apr_dir_make_recursive(path_apr, APR_OS_DEFAULT, pool);
  WIN32_RETRY_LOOP(apr_err, apr_dir_make_recursive(path_apr,

What I believe is happening here, is that the delete of the tmp
directory returns before the directory tmp has been removed, and the
attempt to recreate it is failing when it happens before the actual

Sorry I can't actually make this change and verify it. If someone could
make the change and ship me a svn.exe, I'd be happy to verify the fix.
(And if you include the .pdb file, I can try to debug if it doesn't

I don't think this is the same problem as I was seeing on svnadmin load,
as the transaction directory names are incremented, so there shouldn't
be a problem creating them. (Though perhaps the problem there is just
not enough time for retry under heavy load?). I had to do another
transfer, but since this was Windows to Windows (Server 2003) I just
ROBOCOPY'd the repository instead of doing a dump/reload.

-----Original Message-----
From: Bob Kerns
Sent: Saturday, June 02, 2007 06:59
To: 'D.J. Heap'
Cc: dev@subversion.tigris.org
Subject: RE: svnadmin load errors on Windows

Oh, great! It makes me very happy to hear that you understand the
issue. Given that Windows Explorer, even on Vista, often leaves empty
folders behind when deleting large trees, you get credits for being way
ahead of the pack!

It usually just gets blamed on antivirus software...

Unfortunately, due to health, family, and work, I can't make any
promises, though I'd love to help. The place to look would be where it's
cleaning up completed transactions in the repository.

I've flagged this to follow up in 3 weeks; we'll see if I have more time
(and a C compiler!) by then.

My next migration (in a couple weeks) will be back from Windows to a new
Linux box, so I don't expect to do any more mass series of commits on
Windows, personally... but I've gotten enough value out of Subversion
I'd be pleased to pay some back.

-----Original Message-----
From: D.J. Heap [mailto:djheap@gmail.com]
Sent: Saturday, June 02, 2007 06:06
To: Bob Kerns
Cc: dev@subversion.tigris.org
Subject: Re: svnadmin load errors on Windows

On 5/28/07, Bob Kerns <Bob.Kerns@positscience.com> wrote:
> On Windows, DeleteFile is NOT SYNCHRONOUS; it marks the file for
> after all IO ceases and all handles are closed. This means that if you
> delete all the files in a directory, and then delete the directory, it

Yes, Subversion attempts to deal with this already. See references to
the WIN32_RETRY_LOOP macro in subversion\libsvn_subr\io.c.

It is, of course, possible that code has crept in that does not use
the subversion wrappers for removing files or dirs and so could
exhibit the problem. Do you mind scanning the source for that and
creating a patch if you find any? If you could even scan the source
and file an issue with the details if you find somewhere the
subversion wrappers aren't being used, that would be great too.



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Received on Wed Jun 27 23:10:51 2007

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