Python subprocess blocking and getting BadStatusLine exception

Question

I have a Django web application running on a server (apache), and I'm trying to compile a Java file from the Python code using this:

def comp(request):
   p = subprocess.Popen(['javac',filepath],stdout=subprocess.PIPE,stderr=subprocess.PIPE, bufsize=100)
      res, err =p.communicate()

   return HttpResponse (err)

When calling the comp method I get BadStatusLine exception. I googled about it and I found that the subprocess might be blocking when trying to reed the outputs... so I tried this code:

def comp(request):
   p = subprocess.Popen(['/usr/bin/javac',filepath],stdout=subprocess.PIPE,stderr=subprocess.PIPE, bufsize=100)
   while p.returncode == None:
      res, err =p.communicate()
   if p.returncode != 0:
      err = "whatever"
   return HttpResponse (err) 

it's still blocking

I've tried to write the first code directly to the python interpreter and it worked fine the results are caught successfully from the outputs I guess that the subprocess block have something to do with apache maybe... honestly i don't know what to do next I've tired many methods present in the python doc http://docs.python.org/2/library/subprocess.html but none worked

Thank you for your help.

Answer 1

I've successful installed Celery and I'm using Redis as messaging queue ,I'm able to run the tasks and get the output from any subprocess i launch except for javac the output is always an empty string here is the task code :

class JavaSubTask(Task):

   def run(self, filepath, **kwargs):
      p = subprocess.Popen(["/usr/bin/javac",filepath],stdout=subprocess.PIPE,stderr=subprocess.PIPE)
      p.wait()
      command_output, err = p.communicate()
 return(command_output + err)
tasks.register(JavaSubTask)

I'm running celery with

python manage.py celeryd worker -l INFO

I've tried pexpect module too but gave the same result (and also commands.getstatusoutput too) I've also tried to redirect the output with 2>&1 but also failed

Thanks