What's the correct way to wait "forever"

[vitaly]

A gevent Greenlet in my app starts several objects, then needs to wait "forever" (until the main greenlet kills it), then stops those objects in the finally block. Is there a built-in gevent function that blocks forever, or should I create a gevent.event.Event instance (that will never get set) and wait on it instead?

Thank you,

Vitaly

[AM]

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greenlet = gevent.spawn(...) # or anything else to spawn it
greenlet.join()

will wait for the greenlet to exit.

HTH
AM

[Matt Billenstein]

Take a look at serve_forever() in baseserver.py

m

On Mon, May 20, 2013 at 05:01:28PM -0700, vitaly wrote:
> A gevent Greenlet in my app starts several objects, then needs to wait
> "forever" (until the main greenlet kills it), then stops those objects in
> the finally block. Is there a built-in gevent function that blocks
> forever, or should I create a gevent.event.Event instance (that will never
> get set) and wait on it instead?
> Thank you,
> Vitaly
>
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http://www.vazor.com/

[vitaly]

Thanks everyone for the initial attempts, but those don't work in my scenario because my app does not have access to the underlying greenlets. Let me provide an example to clarify:

def mainGreenthread(self):

  try:

    self.objX.start()

    self.objY.start()

    

    # NEEDED SOMETHING THAT ACCOMPLISHES gevent-friendly "wait forever":

    gevent_wait_forever()

  finally:

    self.objY.stop()

    self.objX.stop()

def start(self):

  self.mainGreenlet = gevent.spawn(self.mainGreenthread)

def stop(self):

  self.mainGreenlet.kill()

So, I was trying to find out whether there is a single function in gevent to accomplish "gevent_wait_forever". I know I can do this via gevent.event.Event().wait(), but it doesn't look terribly elegant, and I was hoping there might be some more elegant alternative.

[Liam Slusser]

You could always do something like...

while True:

    gevent.sleep(60)

liam

On Mon, May 20, 2013 at 5:15 PM, Harry Waye <hw...@arachnys.com> wrote:

It seems by definition you're not blocking forever, instead you're waiting on the main thread sending a kill "event" so yes, an event would be applicable.  Then you'll want to join() that thread to give it time to "stop" its objects.

[Matthias Urlichs]

Hi,

vitaly:

> # NEEDED SOMETHING THAT ACCOMPLISHES gevent-friendly "wait forever":

Create a queue and get() from it

> def stop(self):
> self.mainGreenlet.kill()

that_queue.put(None)

--
-- Matthias Urlichs

[vitaly]

Thank you

[Denis Bilenko]

There's gevent.wait(): it puts main greenlet to sleep while there's
something to do (started servers, open connections, spawned
greenlets).

[vitaly]

On Tuesday, May 21, 2013 6:36:42 AM UTC-7, Denis Bilenko wrote:

There's gevent.wait(): it puts main greenlet to sleep while there's
something to do (started servers, open connections, spawned
greenlets).

gevent.wait() looks like exactly what I needed. I'm still on 1.0b2, so I will be looking forward to gevent.wait() after upgrading.

Thank you,

Vtaly

[Ian Epperson]

gevent.wait() is in every version of gevent - you just need to tell it how long to wait - Liam suggested a while True: gevent.wait(60) which would work for you.  However, it's not really as clean (in my opinion) as just using an event for shutdown.  For instance:

from gevent.event import Event

self.shutdown = Event()

def mainGreenthread(self):

  try:

    self.objX.start()

    self.objY.start()

    

    # NEEDED SOMETHING THAT ACCOMPLISHES gevent-friendly "wait forever":

    self.shutdown.wait()

  finally:

    self.objY.stop()

    self.objX.stop()

def start(self):

  self.mainGreenlet = gevent.spawn(self.mainGreenthread)

def stop(self):

  self.shutdown.set()

Ian.

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[Lars Hansson]

This works pretty well for me:

def signal_shutdown():
    raise KeyboardInterrupt

def main():
    <do stuff>
    gevent.signal(signal.SIGTERM, signal_shutdown)
    forever = gevent.event.Event()
    try:
        forever.wait()
    except KeyboardInterrupt:
        <do stuff>

---
Lars