Mailman 3 February 2005 - Twisted

[Twisted-Python] Need help installing Twisted 1.3 on MacOSX 10.3 with apple installed python
by Jarrod Roberson 18 Feb '05

18 Feb '05

can't find any straight foward instructions on how to do this I am a born-again Mac user ( last mac was a 7200 ) just got a Powerbook and need to get Twisted working ASAP thanks in advance

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[Twisted-Python] socket is not closed when connection failed
by Yun Mao 18 Feb '05

18 Feb '05

Hi everyone, I found that if a TCP connection is failed, e.g. UserTimeout or No route to host, connection refused, etc, i.e. when factory.ConnectionFailed is called, the socket is not properly cleaned up. i.e. socket.close() wasn't called. In this case, when I try to connect to many unreachable hosts, my file descriptor will finally be gone. Could someone confirm me on this? Thanks. I'm using twisted 1.3.0rc1 Yun

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[Twisted-Python] You are made active
by Stephen 17 Feb '05

17 Feb '05

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[Twisted-Python] Persistence in browsers?
by Tibi Dondera 17 Feb '05

17 Feb '05

Hello, I'm not sure if this is the right list, or maybe twisted-web is more appropriate. Also, I might ask a question which has already been answered many times, but I was unable to find references. Short version: I have 10.000 - 100.000 web browsers that are connected to my site, and I need to inform them __real-time__ (a max of 3-5 seconds delay) of an event that happened on the server. Is twisted the right way to go, given the fact that it promises asynchronous event handling ? Long version: I have an information flux on a web page, that must change, as stated before, on some specific event that happens on a server. I have thought of two ways of doing this: 1. The "ask every 5 seconds approach" Pretty obvious, the browser connects every 5 seconds and requests the page again. However, for 10.000 clients, the server soon dies, and the 5 seconds limit is still not respected (because times of response get incredibly long when apache is submerged in requests). 2. The "ask and wait for answer approach" The basic idea is the following: - the browser connects to the web page - there is a javascript snippet in the page that reconnects in the background (using the javascript HTTPRequest object) to a special script on the server. - the server keeps the connection open (by sending spaces, literally, once every 10-15 seconds - and sleeping in between, not to put too much stress on the server either). When an event happens, the server sends all the needed data to the client, that redisplays it (through javascript). Of course, there is the problem with apache and it's 5 minutes script running limit (I have implemented this in PHP), but the javascript code is pretty smart to handle this, and when a connection fails, it reconnects and all goes well. This was a little better than the first approach, at least in the response times, that are now consistent with the requirements. However, a new problem arrises: apache cannot handle a very large number of open connections at the same time (every web browser has at least an open connection, in this case). After my calculations (it's pretty hard to compute exactly, as I know of no javascript-enabled crawler that I can programmatically use), the server will be completely trashed at around 300 connections. The problem gets even more complicated with today's browsers: they have a limitation of 2 concurent connections to the same site (don't know if you noticed, but you cannot download 3 files concurently from the same site). And the HTTPRequest connections count toward this limit. So if a client uses two of my information fluxes, he will be unable to visit the site at the same time. Don't know if twisted solves this last problem. If not, I'll try to find a work around (messing around with the DNS seems like a good idea at this point in time). The question is if twisted can solve my problem of informing all my clients of the event (the event will not happen concurently for all the clients, so there is no problem with server load; however, all the clients will be listening concurently for their specific event) Thanks for any answer, or for any direction/pointers you can give me. I might be totally wrong in my approach, so I'm really open to all suggestions (except buying lots of servers to make this work, of course). Tiberiu DONDERA

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[Twisted-Python] Registration is accepted
by Stephen 17 Feb '05

17 Feb '05

1 0

[Twisted-Python] Both pb.Copyable and pb.RemoteCopy: How to use?
by Steve Freitas 17 Feb '05

17 Feb '05

Hi all! I'm plugging through the pb docs, and a note says that if you want to send an object over the wire in either direction, just make the desired class inherit from both pb.Copyable and pb.RemoteCopy. That's cool. But, what to do after that? Meaning, only the sender can grab a root object (pb.Root), and so only the sender can send jellyable objects out. I realize one answer to this would be to run a server on both sides, but I'm in the situation where my client can contact my server, but not the other way around. So, is it possible for the sender to contact the receiver, and then for them to start swapping objects willy nilly? (Note that the next place I'm going to take this is pb.Cacheable, so beware. :-) ) Thanks! Steve Freitas

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[Twisted-Python] Delivery service mail
by Stephen 16 Feb '05

16 Feb '05

1 0

[Twisted-Python] Is delivered mail
by Stephen 16 Feb '05

16 Feb '05

1 0

[Twisted-Python] using spread/perspective broker
by snacktime 15 Feb '05

15 Feb '05

First off, the main reason I'm looking at this is more for perception than real need. My application is geared for medium/larger sized companies and those people want to know that the software is going to take advantage of their multiple cpu servers. In reality it's an IO bound application and cpu usage would just not be an issue from what I can tell. In any case I'm looking at ways to make it possible for it to run on multiple cpu's by being able to start up several processes and have them share the load. It looks like perspective broker is the right tool for the interprocess communication. My thought was that in a pool of processes, you would designate one of them to handle incoming connections and distribute them to other processes, which process the request, hand it back to the master, which sends the data back to the client. In addition, there should be some way to have the slave processes upgrade themselves to a master if the master process dies. This is all way more complicated than I would like though, and I'm hoping there is possibly a simpler solution. Any ideas?

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[Twisted-Python] twisted.enterprise.adbapi and connection pool problem
by Michal Chruszcz 15 Feb '05

15 Feb '05

Hello, I've noticed a bug(?) or at least misbehaviour in adapi connection pool. I've got a daemon program which keeps a few connections to PostgreSQL database and when a client connects and sends some commands it queries the database and sends back results. Everything works fine, until I restart PostgreSQL. All commands fail and the only trace I've got is the response from the database: #v+ FATAL: terminating connection due to administrator command server closed the connection unexpectedly This probably means the server terminated abnormally before or while processing the request. #v- Restart was clean, while nobody was connected to the daemon. IMHO it shouldn't go this way. Is there any solution to this problem? Or maybe I must take care of myself and try to detect such occurence and recreate dbpool? -- Michal Chruszcz -=- Seen at http://1lo.sanok.pl/~troll/gallery.php

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