Re: python program without stackless.run()

Hi,

I'm not so firm with the channel code, but I think it is fairly simple =

to explain. Have a look at the documentation of the tasklet life cycle: =

https://stackless.readthedocs.org/en/2.7-slp/library/stackless/tasklets.htm=
l#tasklet-life-cycle

As you can see, tasklet can become "current" without a running =

scheduler. At the end of this section there is a simplified =

documentation of the internal working of the stackless.run() function. =

It does not enter a tasklet into the scheduler queue and it is not the =

only way to switch tasklets.

Your example uses 2 tasklets:
1. the main tasklet
2. the tasklet "self.fun"

The line "stackless.tasklet(self.fun)()" creates and schedules tasklet =

fun().

Then the main tasklet sends a message to through the channel self.ch. =

This causes stackless to change the state of the main tasklet to =

"blocked on channel" (See =

https://stackless.readthedocs.org/en/2.7-slp/library/stackless/channels.htm=
l#channel.send =

"If no other tasklet is already receiving on the channel, the sender =

will be blocked."). At the same moment the next tasklet on the schedule =

queue, that is tasklet "self.fun" becomes "current". It receives the =

message from the channel self.ch. This changes the state of the main =

tasklet from "blocked on channel" to "scheduled". Then tasklet self.fun =

runs to the end of method self.fun and terminates. This again triggers =

the scheduler and now the main tasklet becomes current again.

To observe the details, you may want to study the tracing example at
https://bitbucket.org/stackless-dev/stackless/src/9f2a496e6ba2cf9680e357451=
a8d75821d0ebb72/Stackless/demo/tracing.py?at=3D2.7-slp

Regards
   Anselm


Am 22.06.2015 um 13:55 schrieb temp sha:
> hi,
>
> any help in understanding the program will be highly appreciated.
> as per the stackless documentation stackless.run() is must
> to start a scheduler. then how come the below program runs
> the tasklet "fun" without stackless.run() call?
>
>
> thanks in advance.
>
>
> On Fri, Jun 19, 2015 at 2:36 AM, temp sha <[email protected]> wrote:
>> Hi,
>>
>> I could not understand how the below program executes function "fun"
>> without calling stackless.run() in the program?  Here "fun" runs as a
>> tasklet and as per my knowledge for that stackless.run() is must.
>>
>>
>>
>> -----------------------------------------------------------------
>> import stackless
>>
>> class A:
>>      def __init__(self,name):
>>          self.name =3D name
>>          self.ch =3D stackless.channel()
>>          stackless.tasklet(self.fun)()
>>
>>      def __call__(self,val):
>>          self.ch.send(val)
>>
>>      def fun(self):
>>         while 1:
>>           v =3D self.ch.receive()
>>           print "hi" , v
>>
>>
>> if __name__ =3D=3D "__main__":
>>      obj =3D A("sh")
>>      obj(6)
>> -----------------------------------------------------------------
>>
>> output:
>> ----------
>> hi 6
>>
>>
>>
>>
>>
>> thanks,
>> ravi
>
> _______________________________________________
> Stackless mailing list
> [email protected]
> http://www.stackless.com/mailman/listinfo/stackless
>

-- =

  Dipl. Phys. Anselm Kruis                       science + computing ag
  Senior Solution Architect                      Ingolst=E4dter Str. 22
  email [email protected]             80807 M=FCnchen, Germany
  phone +49 89 356386 874  fax 737               www.science-computing.de

-- =

Vorstandsvorsitzender/Chairman of the board of management:
Gerd-Lothar Leonhart
Vorstand/Board of Management:
Dr. Bernd Finkbeiner, Dr. Arno Steitz
Vorsitzender des Aufsichtsrats/
Chairman of the Supervisory Board:
Philippe Miltin
Sitz/Registered Office: Tuebingen
Registergericht/Registration Court: Stuttgart
Registernummer/Commercial Register No.: HRB 382196