[Twisted-Python] Problem with runInteraction and passing a dict variable
Hello, I am both a python and twisted beginner, but I think I have found a problem in twisted. See the code below. The handle_PeerStatus function receives a dict wich contains some info. Then it calls runInteraction with that variable. When the UpdatePeerStatus function is run, block is empty. I did some investigating, it seems that UpdatePeerStatus is run using a workerthread which takes it values from a Queue. When the dict is pushed onto the Queue, it is valid, when when it is popped by the worker thread, the var is empty. Can anybody give me tips to solve this? Am I absolutely missing something and on the wring track or should I enter a bug? Thanks, Ron class ..... def handle_PeerStatus(self, block): print block self.db.runInteraction(self.UpdatePeerStatus, block) def UpdatePeerStatus(self, txn, block): print block # prints {} status = block['PeerStatus'] # throws me an exception
On Sun, 29 Oct 2006 20:57:21 +0100, Ron Arts <ron.arts@netland.nl> wrote:
Simply going through the queue won't mutate the dictionary. Are you certain no other part of your code is manipulating it? One way you could check this is by passing a _copy_ of block to runInteraction so that modifications to the original won't affect it. If this results in things working as you expect, then you've found the problem. In general, you should _not_ be touching the same objects from more than one thread. Passing an object to another thread is fine, but when you do so, you give up all rights to further inspect or modify that object, until such time as the other thread chooses to give it back to you (whereafter it should likewise give up those privileges). Jean-Paul
On Sun, 29 Oct 2006 20:57:21 +0100, Ron Arts <ron.arts@netland.nl> wrote:
Simply going through the queue won't mutate the dictionary. Are you certain no other part of your code is manipulating it? One way you could check this is by passing a _copy_ of block to runInteraction so that modifications to the original won't affect it. If this results in things working as you expect, then you've found the problem. In general, you should _not_ be touching the same objects from more than one thread. Passing an object to another thread is fine, but when you do so, you give up all rights to further inspect or modify that object, until such time as the other thread chooses to give it back to you (whereafter it should likewise give up those privileges). Jean-Paul
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Jean-Paul Calderone -
Ron Arts