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. Does anyone else agree that this should be changed? If so, what should be the correct behavior? (I'm happy to work up a patch and submit it). =Tony.Meyer -- http://mail.python.org/mailman/listinfo/python-list
