Crash in PyStackless_kill_tasks_with_stacks

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Originally reported by: Masamitsu Murase (Bitbucket: masamitsu_murase, GitHub: masamitsu-murase)

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2.7.9-slp causes a crash with the following script in PyStackless_kill_tasks_with_stacks:

#!python

import stackless

def func(ch):
    def comp(a, b):
        print("comp: (%d, %d)" % (a, b))
        ch.receive()
        return a - b

    list = [ 1, 4, 2, 3 ]
    sorted(list, cmp=comp)

channel = stackless.channel()
task = stackless.tasklet(func)(channel)
stackless.run()
channel.send(None)

This crash occurs after Issue #60 was fixed by the pull request #14.

The following is the temporary patch for this issue.
The beginning of slp_cstack_new function in stacklesseval.c should be:

#!c

    ts = NULL;
    if (task && task->cstate)
        ts = task->cstate->tstate;
    if (ts == NULL)
        ts = PyThreadState_GET();

instead of:

#!c

    if (task && task->cstate) {
        ts = task->cstate->tstate;
        assert(ts);
    } else
        ts = PyThreadState_GET();

I replicated this issue with the binary built with Visual C++ 2008 Express Edition on Windows10.

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• Bitbucket: https://bitbucket.org/stackless-dev/stackless/issue/80

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Original comment by Anselm Kruis (Bitbucket: akruis, GitHub: akruis):

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I'm able to reproduce the crash.

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Original comment by Anselm Kruis (Bitbucket: akruis, GitHub: akruis):

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I was able to simplify the test case

#!python
from __future__ import print_function
import stackless

def func():
    global channel
    assert stackless.current.nesting_level == 0
    assert apply(lambda : stackless.current.nesting_level) == 1, "apply does not recurse"
    # apply(channel.receive)  # crash at nesting level 1
    apply(channel.send, (None,))  # crash at nesting level 1
    print("OK")

channel = stackless.channel()
task = stackless.tasklet().bind(func, ())  # simplest tasklet
task.run()

Adding a sys.exitfunc avoids the crash.

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Original comment by Anselm Kruis (Bitbucket: akruis, GitHub: akruis):

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I just committed a test case and the fix proposed by Masamitsu Murase to 2.7-slp. See 655f2a2292a2.

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Original comment by Masamitsu Murase (Bitbucket: masamitsu_murase, GitHub: masamitsu-murase):

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Thank you so much!
Now I can enjoy Stackless Python on EFI Shell ;-)

Regards,
Murase

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Original comment by Anselm Kruis (Bitbucket: akruis, GitHub: akruis):

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Fixed:

• 3.3-slp: 2c9cfd572e63
• 3.4-slp: c8fc6568196e
• default-slp: 0143b05144b3