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jofo
Posted on: 2012/1/21 8:59
Quite a regular
Joined: 2007/1/8
From: Stockholm
Posts: 38
Python threads
I'm trying to spawn a thread from a python script (initiated from x3d file), but it runs terrible slow. My goal is to launch a simple web server to feed data to/from the nodes...
Even if I run a simple thread printing hello world every second it seems stocastic if it will print anything at all. It works find stand-alone python. Any suggestions? H3D 2.1, Linux 32bit.

from H3D import *
from H3DInterface import *
import threading, time

class MyWebserver(threading.Thread):
    def run (self):
        print "gnu"
        while True:
           print "hejsansvejsan"
           time.sleep(1.0)

def initialize():
  MyWebserver().start()


Markus
Posted on: 2012/1/23 16:36
Webmaster
Joined: 2006/3/27
From: SenseGraphics
Posts: 1903
Re: Python threads
Daniel updated something with threads and python during the summer so try with trunk and maybe it will go faster.
karlu
Posted on: 2012/1/23 20:57
Guru
Joined: 2004/12/2
From: Sweden
Posts: 758
Re: Python threads
My experience is that the Python thread is only running when the H3D program is running the Python script. I had to add an auto update with a pause to make it run smoothly:
class App(threading.Thread):
  
  def run(self):
    self.do_stuff()
    
app = App()
app.start()

import time as T
class Ctrl( AutoUpdate( SFTime ) ):
  def update(self, event):
    try:
      T.sleep(.001)
    except:
      pass
    return 0

ctrl = Ctrl()
time.route(ctrl)


----------------
KJ Lundin Palmerius
C Research
Linköping University, Sweden
daniel
Posted on: 2012/1/26 21:18
Webmaster
Joined: 2004/11/28
From:
Posts: 536
Re: Python threads
The underlying problem is that Python threads do not actually run concurrently. Instead only one Python thread runs at any time and Python will determine which thread that runs. Normally a certain number of instructions must be executed in one thread before the next thread is allowed to run the same number of instructions and so on. Because of this the behaviour that karlu mentions(that one has to run Python code from H3D in order for other threads to run as well). In the current development version this is not needed since H3D will explicitly release a global Python lock when not executing in order for other threads to run. If you still have problems with the dev version, please post a bug report.
jofo
Posted on: 2012/2/1 20:19
Quite a regular
Joined: 2007/1/8
From: Stockholm
Posts: 38
Re: Python threads
Hi, thanks, it works well with trunk. Even with the webserver :)

Just a note on compiling it as of yesterday:
include/H3D/CoordinateDeformer.h need
#include <H3D/SFString.h>
then H3DSingleTextureNode.h is not installed to /usr/local/include/H3D automatically.

unfortunately my full application gives segfault w trunk, but thats a separate issue.
Markus
Posted on: 2012/2/2 8:25
Webmaster
Joined: 2006/3/27
From: SenseGraphics
Posts: 1903
Re: Python threads
Issues fixed (one of them I had already fixed but not checked in).

If you ever build on Windows again, consider using the cmake option GENERATE_UNITY_BUILD, makes things go a bit faster (but will be the cause of some include files missing in some headers sometimes).
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