Cython interface to pselect() system call

[Jeroen Demeyer]

Useful for the new doctesting framework.

[Jeroen Demeyer]

I'm intentionally not setting it to needs_review yet, because I want to first have a use case (that will be #12415). But that being said, the code here is supposed to be finished.

[David Roe]

Testing on 5.6 I get a doctest framework error (since you use the new ....: continuation). But testing on 5.7.beta1 with #12415 I get a timeout on line 308 (r, w, x, t = PSelecter().pselect([f,g,f,f,g])).

[Jeroen Demeyer]

Replying to roed:

with #12415 I get a timeout on line 308 (r, w, x, t = PSelecter().pselect([f,g,f,f,g])).

On which kind of system is that?

[David Roe]

Replying to jdemeyer:

Replying to roed:

with #12415 I get a timeout on line 308 (r, w, x, t = PSelecter().pselect([f,g,f,f,g])).

On which kind of system is that?

OS X 10.6.8, Core 2 Duo.

[Jeroen Demeyer]

Updated patch (I haven't looked at the OS X specific issue).

[David Roe]

See ​http://stackoverflow.com/questions/14045801/different-pselect-behaviour-on-osx-vs-linux for a possible explanation of what's going on on OS X.

[Jeroen Demeyer]

Thanks for the pointer, but that doesn't seem to be the problem: no signals are involved in the failing tests you mention.

[Jeroen Demeyer]

New version, works for me on OS X 10.6 with the latest version of #12415. Note that parallel testing on OS X is broken, but normal testing (with -p 1) works.

[David Roe]

Apply failed....

[David Roe]

What was the problem on OS X?

[Jeroen Demeyer]

The problem on OS X is:

sage: import select
sage: f = open(os.devnull)
sage: select.select([],[],[f])
([], [], [<open file '/dev/null', mode 'r' at 0x113ac7420>])

For some reason, most files have an "exceptional condition" by default on OS X. I have no idea why or what this means.

[David Roe]

So is this causing the problems for parallel testing on OS X? Do you know how to get around it?

[Jeroen Demeyer]

Replying to roed:

So is this causing the problems for parallel testing on OS X?

No, this has nothing to do with parallel. The parallel testing should be fixed now.

The parallel testing problem with #12415 on OS X was due to Pdb() importing readline. Importing readline hangs (probably because more than one process tries to take control over the terminal somehow). The solution is simply not starting Pdb if not needed.

[Volker Braun]

Looks good to me. Doesn't actually depend on #12415

[Volker Braun]

I get the following:

Traceback (most recent call last):
  File "/home/vbraun/.sage//tmp/pselect_21760.py", line 458, in <module>
    runner=runner)
  File "/home/vbraun/opt/sage-5.8.beta1/local/bin/sagedoctest.py", line 54, in testmod_returning_runner
    runner=runner)
  File "/home/vbraun/opt/sage-5.8.beta1/local/bin/ncadoctest.py", line 1819, in testmod_returning_runner
    for test in finder.find(m, name, globs=globs, extraglobs=extraglobs):
  File "/home/vbraun/opt/sage-5.8.beta1/local/bin/ncadoctest.py", line 839, in find
    self._find(tests, obj, name, module, source_lines, globs, {})
  File "/home/vbraun/opt/sage-5.8.beta1/local/bin/ncadoctest.py", line 893, in _find
    globs, seen)
  File "/home/vbraun/opt/sage-5.8.beta1/local/bin/ncadoctest.py", line 881, in _find
    test = self._get_test(obj, name, module, globs, source_lines)
  File "/home/vbraun/opt/sage-5.8.beta1/local/bin/ncadoctest.py", line 965, in _get_test
    filename, lineno)
  File "/home/vbraun/opt/sage-5.8.beta1/local/bin/ncadoctest.py", line 594, in get_doctest
    return DocTest(self.get_examples(string, name), globs,
  File "/home/vbraun/opt/sage-5.8.beta1/local/bin/ncadoctest.py", line 608, in get_examples
    return [x for x in self.parse(string, name)
  File "/home/vbraun/opt/sage-5.8.beta1/local/bin/ncadoctest.py", line 570, in parse
    self._parse_example(m, name, lineno)
  File "/home/vbraun/opt/sage-5.8.beta1/local/bin/ncadoctest.py", line 628, in _parse_example
    self._check_prompt_blank(source_lines, indent, name, lineno)
  File "/home/vbraun/opt/sage-5.8.beta1/local/bin/ncadoctest.py", line 715, in _check_prompt_blank
    line[indent:indent+3], line))
ValueError: line 14 of the docstring for __main__.example_6 lacks blank after ...: '            ....:     global got_child'
Exception raised by doctesting framework. Use -verbose for details.

[Jeroen Demeyer]

Replying to vbraun:

I get the following:

Exception raised by doctesting framework. Use -verbose for details.

That's exactly why there was a dependency on #12415, I'm using new doctest syntax.

[David Roe]

I just talked to Volker. Looks good to us.