Can't use bzrlib inside a django app

[Ian Clatworthy]

Importing anything inside bzrlib ends up implicitly calling osutils.register_sigwinch() which breaks Django. Here's the end of the exception:

  2156. class BzrDirFormat4(BzrDirFormat):
File "/usr/lib/python2.6/dist-packages/bzrlib/bzrdir.py" in BzrDirFormat4
  2169. _lock_class = lockable_files.TransportLock
File "/usr/lib/python2.6/dist-packages/bzrlib/lazy_import.py" in __getattribute__
  106. obj = _replace()
File "/usr/lib/python2.6/dist-packages/bzrlib/lazy_import.py" in _replace
  89. obj = factory(self, scope, name)
File "/usr/lib/python2.6/dist-packages/bzrlib/lazy_import.py" in _import
  192. module = __import__(module_python_path, scope, scope, [member])
File "/usr/lib/python2.6/dist-packages/bzrlib/lockable_files.py" in <module>
  64. class LockableFiles(object):
File "/usr/lib/python2.6/dist-packages/bzrlib/lockable_files.py" in LockableFiles
  223. @only_raises(errors.LockNotHeld, errors.LockBroken)
File "/usr/lib/python2.6/dist-packages/bzrlib/lazy_import.py" in __getattribute__
  106. obj = _replace()
File "/usr/lib/python2.6/dist-packages/bzrlib/lazy_import.py" in _replace
  89. obj = factory(self, scope, name)
File "/usr/lib/python2.6/dist-packages/bzrlib/lazy_import.py" in _import
  192. module = __import__(module_python_path, scope, scope, [member])
File "/usr/lib/python2.6/dist-packages/bzrlib/errors.py" in <module>
  20. from bzrlib import (
File "/usr/lib/python2.6/dist-packages/bzrlib/osutils.py" in <module>
  1446. signal.signal(signal.SIGWINCH, _terminal_size_changed)

Exception Type: ValueError at /bzr-alldocs_/
Exception Value: signal only works in main thread

This is rather bad.

[Robert Collins (lifeless)]

On Mon, 2010-03-15 at 06:27 +0000, Ian Clatworthy wrote:
> Public bug reported:
>
> Importing anything inside bzrlib ends up implicitly calling
> osutils.register_sigwinch() which breaks Django. Here's the end of the
> exception:
> ...File "/usr/lib/python2.6/dist-packages/bzrlib/osutils.py" in <module>
> 1446. signal.signal(signal.SIGWINCH, _terminal_size_changed)
>
> Exception Type: ValueError at /bzr-alldocs_/
> Exception Value: signal only works in main thread
>
> This is rather bad.

They should be able to 'work around' this trivially by importing
bzrlib.osutils in their main thread. Its a bit of a python bug that you
can't use signal from any thread, really.

That said, I think this has changed in trunk anyway, so that you have to
create a CLI UI for it to hook now.

-Rob