how to make a web crawler in python

Here is a very simple web crawler in python

import sys, thread, Queue, re, urllib, urlparse, time, os, sys
dupcheck = set()  
q = Queue.Queue(100) 
q.put("http://www.varunpant.com") 
def queueURLs(html, origLink): 
    for url in re.findall(''']+href=["'](.[^"']+)["']''', html, re.I): 
        link = url.split("#", 1)[0] if url.startswith("http") else '{uri.scheme}://{uri.netloc}'.format(uri=urlparse.urlparse(origLink)) + url.split("#", 1)[0] 
        if link in dupcheck:
            continue
        dupcheck.add(link)
        if len(dupcheck) > 99999: 
            dupcheck.clear()
        q.put(link) 
def getHTML(link): 
    try:
        html = urllib.urlopen(link).read() 
        print link
        # open(str(time.time()) + ".html", "w").write("" % link  + "\n" + html) 
        queueURLs(html, link) 
    except (KeyboardInterrupt, SystemExit): 
        raise
    except Exception:
        pass
while True:
    thread.start_new_thread( getHTML, (q.get(),)) 
    time.sleep(0.5)

Varun Pant

how to make a web crawler in python  by  Varun Pant