Python2.5 _zmq.so undefined symbol PyObject_GetBuffer about pyzmq

[minrk]

This error does not happen with my system Python 2.5 on OSX 10.6. Can you give more system details? Cython version if you have it, etc.

[robinp]

Versions: Debian Lenny, Python 2.5.2 (from package), ZeroMQ 2.0.9 from tarball, pyzmq head.

I attached a process to reproduce the thing (assuming Cython is not installed, thus the inserted raise). http://gist.github.com/604388

Also when using the easy_installed Cython-0.13, the unneeded symbols still get generated. The zmq/_zmq.c generated is identical to the bundled one, except the comments about directory location. See: http://gist.github.com/604394

[minrk]

Thanks, I'll look into this.

Writing buffer-protocol code that runs on everything from 2.5-3.x is difficult :)

[ellisonbg]

Yes, looking at mpi4py might help. I think mpi4py runs on everything from 2.3 to 3.x (quite impressive).

[minrk]

I have been looking at mpi4py, but so far I can't find any difference. Those symbols are definitely there in MPI.c in exactly the same contexts, and so far I can't figure out why that wouldn't cause a problem in their code, but does in ours. I'll keep digging.

[minrk]

Well, I still don't know why it works for mpi4py and not us, but I changed buffers (and some multiprocessing imports) which fixes the bug on my py-2.5, and hopefully on yours as well.

Updated code is here:
http://github.com/minrk/pyzmq/tree/py25

Can you test that?

We are about to merge a refactor of the code; as soon as that's done, I will put these fixes in master.

[robinp]

Checked mpi4py and found the solution, see the added file atimport.h and the modified buffers.pxd at the head of git://github.com/robinp/pyzmq.git

With that addition the build zmq imports fine on my Python2.5.

[minrk]

ahhh, thanks for tracking this down - I should have spent some more time ack-ing mpi4py. We'll definitely use one of the two fixes in master after the refactor, probably today.

Can you check that my py25 branch works for you as well?

[robinp]

I checked the py25 branch now, it imports fine and the tests ran :)

What was the method of fix there?

[minrk]

There are actually several symbols that are not in Python < 2.6 in there; the only ones they handle in that header are ones that you can encounter at the top level, everything else is inside an if-statement. I just added a version test, so that the symbols can never be requested on versions < 2.6. See here:
http://github.com/minrk/pyzmq/commit/2f0999c3d5d9803b9f275085937dbf1ddb89683f

I also added some checks around some imports so that the devices submodule works under 2.5.

[minrk]

A variation on these fixes has been merged into trunk, and the code works fine on 2.5