Bugs item #1161031, was opened at 2005-03-10 16:34 Message generated for change (Comment added) made by josiahcarlson You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1161031&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Python Library Group: Python 2.4 Status: Open Resolution: None Priority: 5 Submitted By: Tony Meyer (anadelonbrin) Assigned to: Nobody/Anonymous (nobody) Summary: Neverending warnings from asyncore Initial Comment: Changes in asyncore from 2.3 to 2.4 mean that asyncore.poll() now passes all the sockets in the map to select.select() to be checked for errors, which is probably a good thing. If an error occurs, then handle_expt() is called, which by default logs the error. asyncore.dispatcher creates nonblocking sockets. When connect_ex() is called on a nonblocking socket, it will probably return EWOULDBLOCK (connecting takes time), which may mean the connection is successful, or may not (asyncore dispatcher keeps going assuming all is well). If the connection is not successful, and then asyncore.loop() is called, then select.select() will indicate that there is an error with the socket (can't connect) and the error will be logged. The trouble is that asyncore.loop then keeps going, and will log this error again. My not-that-fast system here gets about 10,000 logged messages per second with a single socket in the asyncore map. There are ways to avoid this: (1) if the socket is blocking when connect()ing (and then nonblocking afterwards) an error is raised if the connect fails. (2) Before calling asyncore.loop(), the caller can run through all the sockets, checking that they are ok. (3) handle_expt() can be overridden with a function that repairs or removes the socket from the map (etc) However, I'm not convinced that this is good behavior for asyncore to have, by default. On Windows, select.select() will only indicate an error when trying to connect (nonblocking) or if SO_OOBINLINE is disabled, but this may not be the case (i.e. errors can occur at other times) with other platforms, right? Unless the error is temporary, asyncore will by default start streaming (extremely fast) a lot of "warning: unhandled exception" (not very helpful an error message, either) messages. Even if the error only lasts a minute, that could easily result in 10,000 warnings being logged. Do any of the python developers agree that this is a flaw? I'm happy to work up a patch for whatever the desired solution is, if so. ---------------------------------------------------------------------- Comment By: Josiah Carlson (josiahcarlson) Date: 2005-05-31 00:31 Message: Logged In: YES user_id=341410 I hate to point out the obvious, but dispatcher is wholly unusable without subclassing. How would you get data to/from a connection without replacing handle_read, handle_write? How do you handle the case when you want to connect to someone else or accept connections from someone else without overloading handle_connect or handle_accept? ---------------------------------------------------------------------- Comment By: Tony Meyer (anadelonbrin) Date: 2005-05-31 00:15 Message: Logged In: YES user_id=552329 Yes this problem is easily solved by subclassing. However I firmly believe that it is a terrible default behaviour, and that it's likely to hit many asyncore users. A class shouldn't have to be subclassed to be usable (ignoring virtual classes and all that), and that really is the case here. The simplest solution would be to change the handler to not log the message. Or log the message once per socket or something. ---------------------------------------------------------------------- Comment By: Josiah Carlson (josiahcarlson) Date: 2005-05-31 00:03 Message: Logged In: YES user_id=341410 Option 1 is not really an option in any case where a large number of connections are opened (so I don't believe should be the default). >From what I understand, certain methods are supposed to be overridden in a subclass if someone using a class wants different behavior. In this case, I believe you can perform either option 2 or 3 in your own code to avoid the thousands of logged lines; either by creating your own loop() function, or by creating a subclass of dispatcher and implementing a handle_expt() method that does as you desire. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1161031&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
