Attachment 704161 Details for Bug 916562 – Better example of why mixing select and readline is bad

Better example of why mixing select and readline is bad

tmp.py (text/plain), 2.53 KB, created by Anders Blomdell on 2013-03-01 13:50:42 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: Anders Blomdell

Created: 2013-03-01 13:50:42 UTC

Size: 2.53 KB

patch

obsolete

>#! /usr/bin/python
>    
>import select
>import threading
>import os
>import time
>
>def start_producer():
>    def producer(f1, f2):
>        print>>f1,'Lock consumer on read 1',
>        f1.flush()
>        time.sleep(1)
>        for n in range(4):
>            print>>f2,n
>            f2.flush()
>            pass
>        print>>f1,', let it loose, line 1 from fd2 will be read'   
>        f1.flush()
>        time.sleep(5)
>        print>>f1,'now all lines will be read'   
>        f1.close()
>        f2.close()
>        pass
>    
>    r1,w1 = os.pipe()
>    r2,w2 = os.pipe()
>    r1 = os.fdopen(r1)
>    r2 = os.fdopen(r2)
>    t1 = threading.Thread(target=producer, 
>                          args=((os.fdopen(w1, 'w'), os.fdopen(w2, 'w'))))
>    t1.daemon =True
>    t1.start()
>    return r1,r2
>
>def mixing_high_and_low_level_is_bad():
>    print 'mixing_high_and_low_level_is_bad'
>    r1,r2 = start_producer()
>    gimmebreak = 0
>    while gimmebreak != 2:
>        gimmebreak = 0
>        readable,_,_ = select.select([r1, r2],[],[], 1)
>        time.sleep(0.1)
>        if r1 in readable:
>            line = r1.readline()
>            if len(line) == 0:
>                gimmebreak += 1
>                pass
>            else:
>                print 'r1:',line.strip()
>                pass
>        if r2 in readable:
>            line = r2.readline()
>            if len(line) == 0:
>                gimmebreak += 1
>                pass
>            else:
>                print 'r2:',line.strip()
>                pass
>            pass
>        pass
>    print
>    pass
>
>def all_low_level_is_better():
>    print 'all_low_level_is_better'
>    r1,r2 = start_producer()
>    gimmebreak = 0
>    buffer = {}
>    buffer[r1] = ''
>    buffer[r2] = ''
>    while gimmebreak != 2:
>        gimmebreak = 0
>        readable,_,_ = select.select([r1, r2],[],[], 1)
>        for r in readable:
>            line = os.read(r.fileno(), 4096)
>            if len(line) == 0:
>                gimmebreak += 1
>                pass
>            else:
>                buffer[r] += line
>                pass
>            pass
>        if '\n' in buffer[r1]:
>            line,buffer[r1] = buffer[r1].split('\n', 1)
>            if len(line) != 0:
>                print 'r1:',line.strip()
>                pass
>            pass
>        if '\n' in buffer[r2]:
>            line,buffer[r2] = buffer[r2].split('\n', 1)
>            if len(line) != 0:
>                print 'r2:',line.strip()
>                pass
>            pass
>        pass
>    print
>    pass
>  
>if __name__ == '__main__':
>    mixing_high_and_low_level_is_bad()
>    all_low_level_is_better()

Actions: View

Attachments on bug 916562: 703876 | 703907 | 703910 | 703925 | 704161 | 704222