Question

I wish to run a long-running script in the background upon receiving a request. I read about subprocess but I require that the call is nonblocking so that the request can complete in time.

def controlCrawlers(request):

    if request.method == 'POST' and 'type' in request.POST and 'cc' in request.POST:

        if request.POST['type'] == '3':
            if request.POST['cc'] == '1':
                    try: #temp solution checking socket is occupied by trying to connect
                        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
                        s.connect(('localhost',DISCOVERY_SOCKET))
                        s.close()

                        return HttpResponse(simplejson.dumps({'success':0,'message': 'Socket is occupied. Possible crawler is already running'}), \
                                        mimetype='application/json')
                    except:
                        pid = os.fork()

                        if pid == 0:
                            #f = open('/home/foo/django','a')
                            #f.write('abc')
                           # f.close()
                            path = os.path.join(os.path.dirname(__file__), 'blogcontentReader/blogpost_crawler.py')
                            os.system("python %s" %path)
                            os._exit(0)

                        return HttpResponse(simplejson.dumps({'success':1,'message': 'Running...'}), \
                                    mimetype='application/json')

I used os.fork as suggested from another post but apparently control does not flow into my if pid == 0 portion. Is this the correct method to do this?

Answer 1

Yeah, don’t do this, use celery instead. It makes running asynchronous tasks a lot easier, more reliable.