Here is how I did it:
#in controller action
import subprocess
subprocess.Popen(r"python applications/{0}/modules/
run.py".format(request.application), shell=True)
On May 19, 6:41 pm, amoygard <[email protected]> wrote:
> Thanks for the answer - I was aware that I don't have to do this to
> handle ajax requests in general. The application I'm building needs to
> send and receive a sequence of messages from the client in a specific
> order, so I thought it would be easier to handle it in one thread/
> process. It is however probably better to do it statelessly as you
> say, so I'll probably have to rewrite the code somewhat.
>
> Out of curiosity though, what is the right way to start a subprocess
> in web2py?
>
> On 19 Mai, 22:00, Yarko Tymciurak <[email protected]> wrote:
>
>
>
> > On May 19, 2:14 pm, amoygard <[email protected]> wrote:
>
> > > Hi,
>
> > > I'm pretty new to web2py and web application frameworks. I'm trying to
> > > create a new background process in controller to handle incoming ajax
> > > data from a user.
>
> > You are trying to do too much: remember: the web is "stateless" ---
> > when _anything_ comes in from a client that gets directed to your URL,
> > (this is just an example flow, so you can get the general idea):
>
> > - somewhere, a DNS server replaces the URI name with a destination
> > address;
> > - the destination server (let's say apache) tries to sort out, and
> > direct to the correct app (in this case, web2py);
> > - web2py's main() parses the path part of the URI to decide how to
> > route internally
> > - if it finds a matching app/controller, main() will set up the
> > execution environment to prepare the call:
> > - i.e., your models are "executed" so that the table definitions,
> > etc. are all in the environment, and then your controller file
> > - the function in your controller is called with this execution
> > environment (this is the thread that you are trying to make, and
> > should not bother)
>
> > The controller function does it's stuff with the request, and returns
> > (to main()) the response - sometimes nothing, sometimes a dict. of
> > stuff;
> > Main takes the return values from the controller, and processes
> > appropriately, most often getting the view, parsing the template,
> > creating the resulting view, and sending it back to the client.
>
> > When an ajax call is made, you can see an example
> > athttp://www.web2py.com/book/default/section/10/3, and explanation of
> > what this does.
>
> > The general point: you call a controller with a request (even in the
> > case of an ajax call);
> > The response goes back to the caller.
>
> > Lots of stuff happens for you - you don't need to write the entire web
> > server underpinnings; just worry about the logic you want to
> > implement so server and client can converse / exchange information.
>
> > Hope this helps.
>
> > Regards,
> > - Yarko
>
> > > I'm using the module multiprocessing for this.
> > > However, when I start the new process, a new instance of web2py server
> > > is started? I'm assuming this has something to do with forking (which
> > > I don't know much about). Is there an easy workaround? Or should I
> > > preferrably do this some other way, for instance with threads?
>
> > > Code is as follows (controller calls function 'someinit' in a module
> > > in module-folder):
>
> > > def tekstpr(mstring,conn):
> > > print mstring
> > > conn.send("hello")
>
> > > def someinit(userid):
> > > from multiprocessing import Pipe, Process
> > > parent_conn, child_conn = Pipe()
> > > p = Process(target=tekstpr,args=("I'm alive!",child_conn))
> > > session.procpipe = parent_conn
> > > p.start()
> > > session.procpipe.poll(300)
> > > return session.procpipe.recv()
