Trac and Subversion

Trac has supported the ​Subversion VersioningSystemBackend since day one. Actually, Trac was even named svntrac back then!

This page is intended to collect all the specific tips and tricks about Subversion support in Trac. This is not the place for general Subversion help. You can get more support options elsewhere.

At the time of this writing, the preferred Subversion version for Trac is still 1.2.3. If you are willing to make a few changes to the stock 1.3.0, that version works also pretty well.

Getting Subversion

From subversion.tigris.org, in the ​download area:

• ​Source archives.
• Pre-built binaries for ​Windows. It's worth noting that starting with 1.4.0, there's now pre-built bindings for Python-2.4.

Building Subversion

The point is not to repeat the excellent build instructions found elsewhere, but rather to clarify the general approach: Trac actually needs the SWIG bindings for Subversion that are bundled with the Subversion distribution. In order to build them, you (obviously) need to build first Subversion, then the bindings.

• Read the INSTALL file that sits at toplevel of the Subversion source distribution
• Do ./configure ...; make; make install; if you intend to use Subversion together with Apache, be sure to configure Subversion so that it will use a compatible version of apr and apr-utils, ideally those of Apache. If not, you'll be able to build Subversion and the bindings, but you most certainly have issues later on, when using mod_python (e.g. #2920).
• Read ./subversion/bindings/swig/INSTALL in order to build the bindings. In particular, pay attention to the version of SWIG which can be required (1.3.0 comes with pregenerated wrappers, though). Do not install swig 1.3.28 or 1.3.29. Version 1.3.27 seems to works fine (Although not in all cases. The subversion users mailing lists suggest going back to 1.3.25, which may be necessary).
• In your subversion source root, do make swig-py; make install-swig-py (NOTE: there is a dash between 'install' and 'swig'!)
• Adapt your PYTHONPATH so that it contains the svn-python folder (the one containing the svn and libsvn packages). If you're using TracModPython, be sure that Apache will also see this environment variable, or alternatively use the PythonPath mod_python directive.

Trac and specific Subversion versions

Trac and Subversion 1.0

This is the oldest supported Subversion version.

Trac and Subversion 1.1

This release introduced the fsfs repository backend, which is to be preferred over the bdb one (see #571 for example). When creating a repository with this Subversion version, take care of using the --fs-type fsfs switch with the svnadmin create command. Version 1.1.4 is the last stable one for that maintenance branch.

Trac and Subversion 1.2

This release makes the fsfs storage the default. Version 1.2.3 is the last stable one for that maintenance branch.

If you switched from a previous version to this one, chances are that you had a Berkeley DB repository. It would be a good idea to switch that repository to the FSFS backend. ​google:svn+convert+bdb+to+fsfs.

Trac and Subversion 1.3

This is the newest major release for Subversion, and it is currently support by Trac 0.9.x and beyond, with a few caveats.

Trac and Subversion 1.3.0

There are a few known issues with the stock 1.3.0 version:

• Issue #2472 (spurious exception)
  which can be fixed by applying this patch to subversion/bindings/swig/python/svn/core.py
  Should be fixed in Subversion 1.3.1 (r17992).
• Issue #2620 (memory leak)
  which can be fixed by applying this patch to subversion/bindings/swig/python/libsvn_swig_py/swigutil_py.c.
  Should be fixed in Subversion 1.3.1 (r18230).

With those fixes, I've been able to use the Subversion backend flawlessly "in production", since end of January 2006.

However, some people are seeing yet another problem, which requires one more fix:

• Issue #2611 (intermittent fatal error, manifesting itself with "argument number 0: a 'apr_pool_t *' is expected" messages in the log and segfault of the apache server)
  was supposedly fixed by applying this patch​ to subversion/bindings/swig/include/proxy_apr.swg. Note that after applying this patch, the SWIG bindings would have to be regenerated, as explained here. It should be emphasized that a compatible version of SWIG must be used (1.3.24, 1.3.25).
  The issue was supposed to be fixed in Subversion 1.3.1, as the above patch was integrated as r18721, but actually the patch was not enough to solve the issue. See below.

Trac and Subversion 1.3.1

As mentioned above, the issues found with 1.3.0 should be fixed by 1.3.1. This is mostly true, except for #2611.

Issue #2611 was confirmed to still exists in Subversion 1.3.1 and also in the stock 1.3.2, when compiled using the pre-generated bindings that were produced using SWIG 1.3.25
So it seems the patch discussed above was not enough to solve the problem. Also, the issue is most certainly related to the use of multiple python sub-interpreters, either because those are created by default when different virtual hosts are used (#2965, #3455) or because different "PythonInterpreter" directives are used in different <Location> sections (#2713). A workaround consists to force the use of a single Python interpreter, using the "PythonInterpreter" directive with the same argument for all the virtual hosts, as explained here.

Trac and Subversion 1.3.2

This version adds support for SWIG 1.3.28.

See also: ​release notes for 1.3.2

Trac and Subversion 1.4

Trac works well with Subversion 1.4.

I've noticed that there has been some improvements to the ra layer … unfortunately not available yet for the Python bindings

Also, that version supports SWIG 1.3.29, but so far I used the 1.3.25 pre-generated wrappers that are bundled with the tarball.

Same remark as above concerning #2611, if I have some time, I'll try to reproduce the issue. Update: according to comment:ticket:2965:14, the problem is still there for 1.4.

See also: ​release notes for 1.4.0

Troubleshooting

RuntimeError: instance.__dict__ not accessible in restricted mode

This is becoming one of the most frequently reported issues for Trac and the Subversion backend, when the TracModPython web front-end is used. The problem happen when Trac is running outside of the "main_interpreter" Python interpreter and can be fixed as explained in #3371.

ImportError: /usr/local/lib/libsvn_ra_dav-1.so.0: undefined symbol: ...

This error manifests itself quite frequently with Subversion 1.4, the undefined symbol in question may differ (gss_delete_sec_context, SSL_shutdown, etc.) See the advices of Garrett McGrath in ​googlegroups:trac-users:1ec307bef7552e5e and also #3706.

SubversionException: ("Expected version '3' of repository; found version '5'", ...

The bindings used are older than the Subversion version used to create the repository (#3943).

SubversionException: ('No such revision XY', 160006)

This kind of error seems to happen frequently. Sometimes it seems to be related to the Trac cache being out-of-sync and needing a manual resync (#2739, #3301, #3728); this can happen if the repository was rebuilt and its UUID hasn't changed. Sometimes it seems to be because the repository is temporarily unavailable (#2346), and sometimes, we simply don't know yet (#3773, #3861, #3875).

Known Issues

#2611

Problem with SVN bindings (SVN 1.3.0, Trac r2771)

#3470

improve handling of scoped repositories with copy history

#4474

diffing two large trees results in a massive list with a lot of empty links

#6615

svn:externals not correctly displayed in browser

#7687

Add support for svn:externals "1.5" style

#7744

source:path@rev targeting a file below a copied dir may fail

#8813

next_rev is slow, particularly in the direct-svnfs case

#9208

Support for SVN repository on a UNC path on Windows

#10079

improper rendering of svn:externals when not configured

#10421

RuntimeError: instance.__dict__ not accessible in restricted mode

#10547

glitch with mergeinfo (recreation of merge source shown as eligible)

#11205

"repository sync" fails for Subversion repository with unicode path

#12121

Subversion copies could show peg revision in browser view

#13624

svn-browser generates wrong links directly after renaming/moving files

Asking for More Support About Subversion

• ReadTheFineBook: ​http://svnbook.red-bean.com and/or the ​FAQ
• There's also a #svn channel on the freenode IRC network
• If you think you've found a bug in Subversion, read these ​instructions