Re: Webware/Apache Threading Problem?

John Dickinson wrote:
> Maybe I'm a little dense here, but I'm not seeing why os.chdir is such a 
> bad thing in a threaded environment. I did a little google-ing, but I 
> did not find anything the was talking about problems in a threaded 
> environment.

The following program shows the problem quite clearly:

----------------------------

from os import mkdir, chdir
from time import sleep
from threading import Thread

try:
     # make test dirs
     mkdir('dir1')
     mkdir('dir1/dir2')
     open('dir1/test', 'w').write('inside dir1')
     open('dir1/dir2/test', 'w').write('inside dir2')
except:
     pass

def thread1():
     chdir('dir1')
     sleep(0.2)
     print "test file in dir1:", open('test').read()

def thread2():
     sleep(0.1)
     chdir('dir2')

Thread(target=thread1).start()
Thread(target=thread2).start()

----------------------------

 From looking at the thread1 function, you would expect "inside dir1" as 
output, but because thread2 is interfering, it prints "inside dir2".

I have added the sleep calls to make the behavior predictable. In a real 
threaded environment, the output would be unpredictable.

-- Chris

-------------------------------------------------------------------------
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642