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cym13 opened this issue Mar 22, 2015 · 3 comments
Open

os.waitpid that never ends with "sh" library #512

cym13 opened this issue Mar 22, 2015 · 3 comments
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@cym13
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cym13 commented Mar 22, 2015

Hi,

Here is the stackstrace:

$ /usr/bin/bpython

bpython version 0.14.1 on top of Python 3.4.3 /usr/bin/python
>>> from sh import ls, cat
>>> ls()
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "/usr/lib/python3.4/site-packages/sh.py", line 769, in __call__
    return RunningCommand(cmd, call_args, stdin, stdout, stderr)
  File "/usr/lib/python3.4/site-packages/sh.py", line 330, in __init__
    self.wait()
  File "/usr/lib/python3.4/site-packages/sh.py", line 334, in wait
    self._handle_exit_code(self.process.wait())
  File "/usr/lib/python3.4/site-packages/sh.py", line 1152, in wait
    pid, exit_code = os.waitpid(self.pid, 0)
InterruptedError: [Errno 4] Interrupted system call
>>> cat("./test.py")
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "/usr/lib/python3.4/site-packages/sh.py", line 769, in __call__
    return RunningCommand(cmd, call_args, stdin, stdout, stderr)
  File "/usr/lib/python3.4/site-packages/sh.py", line 330, in __init__
    self.wait()
  File "/usr/lib/python3.4/site-packages/sh.py", line 334, in wait
    self._handle_exit_code(self.process.wait())
  File "/usr/lib/python3.4/site-packages/sh.py", line 1152, in wait
    pid, exit_code = os.waitpid(self.pid, 0)
InterruptedError: [Errno 4] Interrupted system call

Each call to a function imported through sh never ends, the previous
exceptions were thrown only when I forced it to flush by resizing the window.
The same lines were tested with python3 and ipython3 without problem.

It may be of importance to know my system:

$ uname -a
Linux Eather 3.19.2-1-ARCH #1 SMP PREEMPT Wed Mar 18 16:21:02 CET 2015 x86_64 GNU/Linux
@sebastinas sebastinas added the bug label Mar 22, 2015
@sebastinas
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This might be a consequence of using greenlets. The old curses interface does not show this behavior.

@jquast
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jquast commented Feb 1, 2016

The same lines were tested with python3 and ipython3 without problem.

All python functions using system calls now gracefully retry when interrupted in python3.5, pep-475: https://www.python.org/dev/peps/pep-0475/

The only fix would be upstream sh.py module, to wrap os.waitpid with while True loop, continuing on InterruptedError, breaking otherwise.

@jquast
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jquast commented Feb 1, 2016

Also window resizes cause a signal (SIGWINCH), this is why os.waitpid is interrupted.

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@sebastinas @jquast @cym13