Process spawn hangs forever (MacOS)

[schlamar]

If I execute this simple script:

import pyuv

loop = pyuv.Loop.default_loop()
proc = pyuv.Process(loop)
proc.spawn('ls', lambda *a: None)
loop.run()

The loop.run hangs forever, it even can't be stopped with SIGINT (Ctrl+C). Happens on Python 2.7 and Python 3.3.

[schlamar]

With

for i in xrange(10):
    print (i)
    loop.run(pyuv.UV_RUN_ONCE)

it hangs at the second call to loop.run

[saghul]

This is not a bug, the loop will keep looping until no active handles are left, and process handles are always active until you call close() on them.

This one works:

import pyuv

loop = pyuv.Loop.default_loop()
proc = pyuv.Process(loop)
proc.spawn('ls', lambda *a: proc.close())
loop.run()

[schlamar]

@saghul
Well, in this case there is a behavior issue on Windows, because this terminates:

import pyuv

loop = pyuv.Loop.default_loop()
proc = pyuv.Process(loop)
proc.spawn('dir', lambda *a: None)
loop.run()

[saghul]

I checked the code and indeed it's clear that this is handled differently. I'll report this to the libuv guys. Nevertheless, and as a rule of thumb when using pyuv, always close() handles where you are done with them. They are automatically closed if the Python object is garbage collected, but you never know when that will happen. Moreover, if you don't call close() you need to know the event loop internals to actually know when a handle is active or not, because an active handle will prevent loop.run() from returning (unless it's unref'd, but that was not this case).

[saghul]

I reported this and it has already been fixed in libuv! joyent/libuv#718 I'll bump the libuv revision shortly and it will work the same on Windows and Unix.