git-svn intermittent issues with absent_file

git-svn intermittent issues with absent_file

[Matthias Andree]

Greetings,

we seem to have issues with checking out files from an SVN server via  
https://. The problem is hard to reproduce, and shows as "absent_file"  
warnings, i. e. files that are in the SVN checkout don't make it to the  
Git checkin.

Perhaps this rings a bell with someone or there are similar reports that  
relate to our issues...


## ISSUE ## Once in a while, a git-svn clone or rebase fails with files  
missing from commits, as mentioned above. We haven't been able to figure  
out under what circumstances this happens. If we try to reproduce this (i.  
e. kill the directory completely and re-run the git svn clone), another  
revision (for instance 170) might show this, or the clone may succeed.
   This was observed with Git 1.6.0.4 under Ubuntu Linux Jaunty Jackalope  
(9.04) and on a different computer with Git 1.6.4.1.196.g31f0b (from the  
master branch) under a fully updated Cygwin 1.5.


Example log of failed data (sorry, we are not allowed to let you access  
the repository, so we must debug by proxy).
I'm replacing substrings in the log below to maintain corporate  
confidentiality levels:

$ git svn clone --no-checkout https://svnserver.example.edu/project/
Initialized empty Git repository in /tmp/compnet/.git/
W: +empty_dir: branches
W: +empty_dir: tags
W: +empty_dir: trunk
r1 = a1b0e99e3986da4d8d461944b623b6abb2460de4 (refs/remotes/git-svn)
...
r135 = 294077e62ee5f463b8ab97d961d9742ef89ae662 (refs/remotes/git-svn)
         A       ... (~100 PDF files)
       ...
         A       d1/u1/2009_06/f1.pdf
W: +empty_dir: d1/u2/slides/2009_06
W: absent_file: d1/u1/2009_06/d1/u1/2009_06/f2.pdf Insufficient  
permissions?
W: absent_file: d1/u3/06_2009/f1/u3/2009_06/f3.pdf Insufficient  
permissions?
W: absent_file: d1/u2/slides/2009_06/d1/u2/slides/2009_06/f4.pdf  
Insufficient permissions?
r136 = 58523cf1fa867d33a74080dabdcbc85ae0ba99ec (refs/remotes/git-svn)
...
r139 = 2fb1647bc40d3815a5eefb32d43a375e03d2e871 (refs/remotes/git-svn)
Incomplete data: Delta source ended unexpectedly at  
/usr/local/libexec/git-core/git-svn line 4605


Just re-running "git svn fetch" reproduces the "Incomplete data:" error  
and aborts, but re-fetching an older version succeeds. No fiddling with  
permissions needed.


## WORKAROUND ##

If this happens, I can force a checkout with, say, "git checkout -t -b  
master remotes/git-svn", revert to the last good revision with "git svn  
reset -r135" (this doesn't work without prior checkout) and then re-run  
git svn fetch, which will usually succeed then.


The three absent_file lines are also recorded in  
.git/svn/refs/remotes/git-svn/unhandled.log for r136.


Questions:

1. What causes these absent_file issues? How can we assist with debugging  
this?

2. What does "Delta source ended unexpectedly" mean? (the line number is  
bogus, it's just the finish_report call)

3. Is this or a similar issue known? Is this an issue with the SVN server,  
the SVN bindings, or the git svn adaptor?

4. How can we avoid or fix this?

We're happy to test patches.


Thanks a lot in advance.

Cheers,

-- 
Matthias Andree

Re: git-svn intermittent issues with absent_file

[Eric Wong]

Matthias Andree <matthias.andree@uni-paderborn.de> wrote:
> Greetings,
>
> we seem to have issues with checking out files from an SVN server via  
> https://. The problem is hard to reproduce, and shows as "absent_file"  
> warnings, i. e. files that are in the SVN checkout don't make it to the  
> Git checkin.
>
> Perhaps this rings a bell with someone or there are similar reports that  
> relate to our issues...

Hi Matthias,

I don't recall any issues with the "absent_file" callback ever being
reported to me.  I don't think I've ever touched a repo that triggered
it, either...

> ## ISSUE ## Once in a while, a git-svn clone or rebase fails with files  
> missing from commits, as mentioned above. We haven't been able to figure  
> out under what circumstances this happens. If we try to reproduce this 
> (i. e. kill the directory completely and re-run the git svn clone), 
> another revision (for instance 170) might show this, or the clone may 
> succeed.
>   This was observed with Git 1.6.0.4 under Ubuntu Linux Jaunty Jackalope  
> (9.04) and on a different computer with Git 1.6.4.1.196.g31f0b (from the  
> master branch) under a fully updated Cygwin 1.5.

I assume this happens with the latest git under Ubuntu Linux, too; but
can you give that a try just in case?

There have been a few odd bugs fixed since 1.6.0.4, but nothing rings a
bell here.  This doesn't seem to be a Cygwin/Win32-related issue, but
I'd like to minimize the number of variables since I can't support
Cygwin/Win32 directly.

> Example log of failed data (sorry, we are not allowed to let you access  
> the repository, so we must debug by proxy).
> I'm replacing substrings in the log below to maintain corporate  
> confidentiality levels:
>
> $ git svn clone --no-checkout https://svnserver.example.edu/project/
> Initialized empty Git repository in /tmp/compnet/.git/
> W: +empty_dir: branches
> W: +empty_dir: tags
> W: +empty_dir: trunk
> r1 = a1b0e99e3986da4d8d461944b623b6abb2460de4 (refs/remotes/git-svn)
> ...
> r135 = 294077e62ee5f463b8ab97d961d9742ef89ae662 (refs/remotes/git-svn)
>         A       ... (~100 PDF files)
>       ...
>         A       d1/u1/2009_06/f1.pdf
> W: +empty_dir: d1/u2/slides/2009_06
> W: absent_file: d1/u1/2009_06/d1/u1/2009_06/f2.pdf Insufficient  
> permissions?
> W: absent_file: d1/u3/06_2009/f1/u3/2009_06/f3.pdf Insufficient  
> permissions?
> W: absent_file: d1/u2/slides/2009_06/d1/u2/slides/2009_06/f4.pdf  
> Insufficient permissions?
> r136 = 58523cf1fa867d33a74080dabdcbc85ae0ba99ec (refs/remotes/git-svn)
> ...
> r139 = 2fb1647bc40d3815a5eefb32d43a375e03d2e871 (refs/remotes/git-svn)
> Incomplete data: Delta source ended unexpectedly at  
> /usr/local/libexec/git-core/git-svn line 4605
>
>
> Just re-running "git svn fetch" reproduces the "Incomplete data:" error  
> and aborts, but re-fetching an older version succeeds. No fiddling with  
> permissions needed.
>
>
> ## WORKAROUND ##
>
> If this happens, I can force a checkout with, say, "git checkout -t -b  
> master remotes/git-svn", revert to the last good revision with "git svn  
> reset -r135" (this doesn't work without prior checkout) and then re-run  
> git svn fetch, which will usually succeed then.
>
>
> The three absent_file lines are also recorded in  
> .git/svn/refs/remotes/git-svn/unhandled.log for r136.
>
>
> Questions:
>
> 1. What causes these absent_file issues? How can we assist with debugging 
> this?

Permissions would be my first (and only) guess as I have no experience
with this condition...

Are you using anything weird in ~/.subversion/config by any chance?
And you're sure you're using the same user/account in all cases?

Are the files you're hitting absent_file on unusually large and
hitting some limit on the server side?

> 2. What does "Delta source ended unexpectedly" mean? (the line number is  
> bogus, it's just the finish_report call)

Sometimes the server can just shut down/drop connections.  Do you have
access to the server logs?  How many simultaneous connections can
it accept?  Which version of the Subversion server is running?
How reliable is your network connection to the server?

Anything weird with the network configuration?  Mismatched MTU, odd
firewall rules, non-standard TCP stack configuration, VPN, proxies...

> 3. Is this or a similar issue known? Is this an issue with the SVN 
> server, the SVN bindings, or the git svn adaptor?

The "Incomplete data: Delta source ended unexpectedly" happens
from time to time on a few odd servers, but I've never found it
reproducible and retrying "git svn fetch" always fixes it.
This is more than likely the fault of the network or server.

The "absent_file" issue I've never seen...

> 4. How can we avoid or fix this?

Other than your workaround, I don't know...

> We're happy to test patches.

Cool.  I don't have any ideas for patches right now, but does this
problem happen with other SVN clients?  Even svk/svm could be
worth a shot for testing...

-- 
Eric Won

Re: git-svn intermittent issues with absent_file

[Matthias Andree]

Am 27.08.2009, 21:19 Uhr, schrieb Eric Wong <normalperson@yhbt.net>:

> Matthias Andree <matthias.andree@uni-paderborn.de> wrote:
>> Greetings,
>>
>> we seem to have issues with checking out files from an SVN server via
>> https://. The problem is hard to reproduce, and shows as "absent_file"
>> warnings, i. e. files that are in the SVN checkout don't make it to the
>> Git checkin.
>>
>> Perhaps this rings a bell with someone or there are similar reports that
>> relate to our issues...
>
> Hi Matthias,
>
> I don't recall any issues with the "absent_file" callback ever being
> reported to me.  I don't think I've ever touched a repo that triggered
> it, either...

Hi Eric,

thank you for the prompt reply.

>> ## ISSUE ## Once in a while, a git-svn clone or rebase fails with files
>> missing from commits, as mentioned above. We haven't been able to figure
>> out under what circumstances this happens. If we try to reproduce this
>> (i. e. kill the directory completely and re-run the git svn clone),
>> another revision (for instance 170) might show this, or the clone may
>> succeed.
>>   This was observed with Git 1.6.0.4 under Ubuntu Linux Jaunty Jackalope
>> (9.04) and on a different computer with Git 1.6.4.1.196.g31f0b (from the
>> master branch) under a fully updated Cygwin 1.5.
>
> I assume this happens with the latest git under Ubuntu Linux, too; but
> can you give that a try just in case?

The latest git was on Cygwin, but we'll see to trying it on Linux.

> There have been a few odd bugs fixed since 1.6.0.4, but nothing rings a
> bell here.  This doesn't seem to be a Cygwin/Win32-related issue, but
> I'd like to minimize the number of variables since I can't support
> Cygwin/Win32 directly.

The other question is how many arcane APR or Subversion binding issues we
hit here. Subversion 1.6 + bindings surely is rather picky on Cygwin 1.5,
as discussed earlier on this list.

>> Questions:
>>
>> 1. What causes these absent_file issues? How can we assist with  
>> debugging
>> this?
>
> Permissions would be my first (and only) guess as I have no experience
> with this condition...

Hm. In that case: who writes the file that goes missing, and why isn't the
error logged then? Is there a way to have the SVN bindings or the
interfacing code in Git-SVN log file creation/write errors with decoded
errno? That might help a big deal already.

> Are you using anything weird in ~/.subversion/config by any chance?

Not to my knowledge.

> And you're sure you're using the same user/account in all cases?

Yes indeed. All under the same account.

> Are the files you're hitting absent_file on unusually large and
> hitting some limit on the server side?

The files aren't, the whole changeset might. We haven't yet observed this
on small (as in one .tex file) commits.

>> 2. What does "Delta source ended unexpectedly" mean? (the line number is
>> bogus, it's just the finish_report call)
>
> Sometimes the server can just shut down/drop connections.  Do you have
> access to the server logs?  How many simultaneous connections can
> it accept?  Which version of the Subversion server is running?

The server doesn't permit user logins, so we need to ask the support
staff. Answer times are unpredictable.

> How reliable is your network connection to the server?
> Anything weird with the network configuration?  Mismatched MTU, odd
> firewall rules, non-standard TCP stack configuration, VPN, proxies...

Uncritical. Company network, "direct connection" (through switches).

>> 3. Is this or a similar issue known? Is this an issue with the SVN
>> server, the SVN bindings, or the git svn adaptor?
>
> The "Incomplete data: Delta source ended unexpectedly" happens
> from time to time on a few odd servers, but I've never found it
> reproducible and retrying "git svn fetch" always fixes it.
> This is more than likely the fault of the network or server.

Seems plausible, but...

> The "absent_file" issue I've never seen...

...in such a case, some part of the overall system (I'm not saying it's  
git-svn though) must ignore an error and continue.

>> We're happy to test patches.
>
> Cool.  I don't have any ideas for patches right now, but does this
> problem happen with other SVN clients?  Even svk/svm could be
> worth a shot for testing...

I can try svk, but what's svm?

-- 
Matthias Andree

Re: git-svn intermittent issues with absent_file

[Matthias Andree]

Am 28.08.2009, 08:58 Uhr, schrieb Matthias Andree  
<matthias.andree@uni-paderborn.de>:

> The other question is how many arcane APR or Subversion binding issues we
> hit here. Subversion 1.6 + bindings surely is rather picky on Cygwin 1.5,
> as discussed earlier on this list.

As an update, Git-SVN 1.6.4.0 and 1.6.4.1 haven't seen such problems last  
night when run on Ubuntu Linux.

So, the common idea set is apparently down to (a) intermittent server  
issues (I've asked for the relevant log excerpts) and (b) Cygwin issues,  
and we should keep in mind (c) git-svn, or svn bindings/libraries, losing  
the causes error conditions from (a) or (b) and git-svn just reporting  
later symptoms (absent files). More on the other experiments once I get  
around to them.

Thanks
Matthias

Re: git-svn intermittent issues with absent_file

[Ealdwulf Wuffinga]

On Fri, Aug 28, 2009 at 9:14 AM, Matthias
Andree<matthias.andree@uni-paderborn.de> wrote:

> So, the common idea set is apparently down to (a) intermittent server issues
> (I've asked for the relevant log excerpts) and (b) Cygwin issues, and we
> should keep in mind (c) git-svn, or svn bindings/libraries, losing the
> causes error conditions from (a) or (b) and git-svn just reporting later
> symptoms (absent files). More on the other experiments once I get around to
> them.

Won't help if it's a server issue, but if your suspicion towards
git-svn (or anything else you have the source for) increases, it may
be worth trying bbchop:
http://github.com/Ealdwulf/bbchop
That is like git-bisect, except it can cope with intermittent bugs.

Ealdwulf