ofThread consumes 100% CPU usage

beginners
1

Hi, I’m trying to use ofThread but it is really expensive just for using the empty while loop in the threaded function.

Here’s my code.

Everything in ofApp.h and nothing in ofApp.cpp

#pragma once

#include "ofMain.h"

class myThread : public ofThread {
    
public:
    
    myThread(){
        
        startThread();
    }
    ~myThread(){
        
        stopThread();
    }
    
private:
    
    void threadedFunction()
    {
        while (isThreadRunning()) {
            
        }
    }
};

class ofApp : public ofBaseApp{
	public:
		void setup();
		void update();
		void draw();
		
		void keyPressed(int key);
		void keyReleased(int key);
		void mouseMoved(int x, int y);
		void mouseDragged(int x, int y, int button);
		void mousePressed(int x, int y, int button);
		void mouseReleased(int x, int y, int button);
		void mouseEntered(int x, int y);
		void mouseExited(int x, int y);
		void windowResized(int w, int h);
		void dragEvent(ofDragInfo dragInfo);
		void gotMessage(ofMessage msg);

    myThread thread;
};

When I run this code, the CPU is over 100%.
Is it normal? I’m using OF v0.9.8 on Mac OS X 10.11.6.
Any advise or guidance would be greatly appreciated!

2

Hi! Just guessing here, but could it be that the empty while loop is like an infinite loop? Maybe sleeping a bit helps? :slight_smile: See http://openframeworks.cc/documentation/utils/ofThread/#show_sleep

Update: from that document:

If the user does not give the thread a chance to sleep, the thread may take 100% of the CPU core while it’s looping as it waits for something to do. This may lead to poor application performance.

1 Like
3

hey yes if you just have a while loop it’ll run as fast as possible and even if it’s only checking isThreadRunning it’s checking it as much as it can using a full cpu. as @hamoid says you usually sleep a bit between loop cycles or even better use a thread channel so the thread only wakes up when there’s data to process

1 Like
4

That makes sense. I decided to use a thread channel. Thank you so much guys!