Bugs item #1469557, was opened at 2006-04-12 17:13
Message generated for change (Comment added) made by brucepeterson
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Category: Python Library
Group: Python 2.4
Status: Closed
Resolution: Invalid
Priority: 5
Submitted By: brucepeterson (brucepeterson)
Assigned to: Nobody/Anonymous (nobody)
Summary: FTP modue functions are not re-entrant,give odd exceptions
Initial Comment:
If I define a class using the Thread and FTP moudles,
start a process which gathers FTP responses,
additional calls to the class may have the responses
of the thread instead of the main loop (or vice versa)
This causes weird and unexpected exceptions from the
ftplib.
For instance I get the following error when the
thread process does a pwd() function
error_reply: 213 34603008
The "213" reply is a response from the main process
size() function
---------
Code
---------
from time import sleep
from threading import Thread
class ftpMachine(Thread, ftplib.FTP):
def __init__(self, svr, user, passwd):
Thread.__init__(self)
ftplib.FTP.__init__(self, svr, user, passwd)
def run(self):
for x in xrange(20):
output="Thread -"+str(self.nlst())[:30]
print output
sleep (0.0100)
def main():
aCon = ftpMachine("LocalFTP", "user", "")
aCon.start()
for x in xrange(20):
output = "Main -- " + str(aCon.size("File"))
print output
sleep (0.010)
Workround:
Rewrite code to create a third worker thread for
response isolation? Don't know that this would solve
the problem.
---------------
Exception example
---------------
Exception in thread Thread-1:
Traceback (most recent call last):
File "C:\Python24\lib\threading.py", line 442, in
__bootstrap
self.run()
File "dualFTPIssue.py", line 17, in run
output = "Thread output " + str(self.nlst())[:30]
+" ..."
File "C:\Python24\lib\ftplib.py", line 448, in nlst
self.retrlines(cmd, files.append)
File "C:\Python24\lib\ftplib.py", line 396, in
retrlines
conn = self.transfercmd(cmd)
File "C:\Python24\lib\ftplib.py", line 345, in
transfercmd
return self.ntransfercmd(cmd, rest)[0]
File "C:\Python24\lib\ftplib.py", line 321, in
ntransfercmd
host, port = self.makepasv()
File "C:\Python24\lib\ftplib.py", line 299, in
makepasv
host, port = parse227(self.sendcmd('PASV'))
File "C:\Python24\lib\ftplib.py", line 566, in
parse227
raise error_reply, resp
error_reply: 213 34603008
----------------------------------------------------------------------
>Comment By: brucepeterson (brucepeterson)
Date: 2006-07-27 14:39
Message:
Logged In: YES
user_id=1500983
Unfortunately I can't start two instances of the FTP client
as the separate instances use two conneciton resources. I
was hoping for a non-exception when a unexpsected response
happens. That would require re-working the module.
For my workaround I set a time to determine when the
transfer should complete instead of a querry.
Thanks for your attention in this matter.
Closing this bug as my case is an unusual one.
----------------------------------------------------------------------
Comment By: Ronald Oussoren (ronaldoussoren)
Date: 2006-07-13 04:54
Message:
Logged In: YES
user_id=580910
IMHO this isn't a bug, your accessing a shared resource (the FTP connection)
from two threads without locking. Most of python's libraries aren't safe for
this
kind of use.
BTW. The fact that you subclass form thread and ftplib.FTP is immaterial, you
will get the same effect if you create an ftplib.FTP and then use it in two
threads.
----------------------------------------------------------------------
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