Start background process/daemon from CGI script

Question

I\'m trying to launch a background process from a CGI scripts. Basically, when a form is submitted the CGI script will indicate to the user that his or her request is being

Answer 1

My head still hurting on that one. I tried all possible ways to use your code with fork and stdout closing, nulling or anything but nothing worked. The uncompleted process output display depends on webserver (Apache or other) config, and in my case it wasn't an option to change it, so tries with "Transfer-Encoding: chunked;chunk=CRLF" and "sys.stdout.flush()" didn't worked either. Here is the solution that finally worked.

In short, use something like:

if len(sys.argv) == 1:  # I'm in the parent process
   childProcess = subprocess.Popen('./myScript.py X', bufsize=0, stdin=open("/dev/null", "r"), stdout=open("/dev/null", "w"), stderr=open("/dev/null", "w"), shell=True)
   print "My HTML message that says to wait a long time"
else: # Here comes the child and his long process
   # From here I cannot print to Webserver, but I can write in files that will be refreshed in my web page.
   time.sleep(15)  # To verify the parent completes rapidly.

I use the "X" parameter to make the distinction between parent and child because I call the same script for both, but you could do it simpler by calling another script. If a complete example would be useful, please ask.