On 12:13 pm, a.libran@gmail.com wrote:

Regarding

...

The process ''starting'' is different from `ProcessProtocol` methods being called. `ProcessProtocol.processEnded` is ''not'' called until the reactor is running.

On my own VMs, the processEnded gets called

[root@master1 play]# cat fun.py from twisted.internet import reactor

from twisted.internet import reactor, protocol

class OneRun(protocol.ProcessProtocol): def processEnded(self, reason): print "Process ended\n"

reactor.spawnProcess(OneRun(), executable="echo", args=["echo", "hello"], childFDs={0:0, 1:1, 2:2}) [root@master1 play]# python fun.py hello Process ended

[root@master1 play]#

But once again, on a different VM, I only see "hello" and processEnded isn't called.

Both VMs run Python 2.7.1 and Twisted 11.0.0

What is going on?

Thanks for this follow-up. I noticed that in this snippet, there's no `reactor.run()� call at all. This is a better example, since it shows `processEnded� being called even though there's no chance of the reactor ever being running. Investigating this, I see that there is an early- exit case in process support (in `twisted/internet/process.py�, line 65) which may call `processEnded� even when the reactor is not running. Inserting a sleep(1) before the `os.waitpid� call in that function makes it much more likely to trigger this case, since it gives the child plenty of time to exit.

This strikes me as a bug. Can you file a new ticket for this?

Thanks again, Jean-Paul

David Kao

On Mon, Sep 26, 2011 at 8:03 PM, Twisted trac@twistedmatrix.com wrote:

...

#5272: In the core doc, do not call reactor.stop directly in processEnded ------------------------+--------------------------------------------------- � � Reporter: �dkdog � | � � � � � Owner: � � � � Type: �defect �| � � � � �Status: �closed � � Priority: �normal �| � � � Milestone: � �Component: �core � �| � � �Resolution: �worksforme � � Keywords: � � � � �| � � � � �Branch: Branch_author: � � � � �| � Launchpad_bug: ------------------------+--------------------------------------------------- Changes (by exarkun):

�* status: �reopened => closed �* resolution: �=> worksforme

Comment:

�> I just found out that reactor.spawnProcess could spawn the subprocess �right away **before** reactor.run is executed.

�This doesn't seem related to this ticket.

�> I get the impression that most stuff don't get run until the reactor �event loop is up and running with reactor.run()

�That's true. �Most stuff.

�> In this case, who's answering all the ProcessProtocol's methods like �processEnded then, without an event loop?

�The process ''starting'' is different from `ProcessProtocol` methods being �called. �`ProcessProtocol.processEnded` is ''not'' called until the �reactor is running.

�Further discussion should be moved to the mailing list. �Thanks.

-- Ticket URL: http://twistedmatrix.com/trac/ticket/5272#comment:8 Twisted http://twistedmatrix.com/trac/ Engine of your Internet

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