Simon Willison’s Weblog

Comet (long polling) for all browsers using ScriptCommunicator. More Comet from the Plurk team: 80 lines of dependency free JavaScript implementing long polling using script tags (hence working cross-domain) across IE6+, Firefox, WebKit and Opera. The clever bit is the code to detect loading errors. It doesn’t try to fix the infinite loading indicator problem—is that still a cromulent usability concern? 3rd February 2010, 12:37 am

Distributed lock on top of memcached. A simple Python context manager (taking advantage of the with statement) that implements a distributed lock using memcached to store lock state: “memcached_lock can be used to ensure that some global data is only updated by one server”. Redis would work well for this kind of thing as well. 1st February 2010, 10:15 am

Plurk: Instant conversations using Comet (via) Plurk’s comet implementation sounds pretty amazing. They’re using a single quad-core server with 32GB of RAM running 8 Node.js instances to serve long-polled comet to 100,000+ simultaneous users. They switched to Node from Java JBoss/Netty and found the new solution used 10 times less memory. 1st February 2010, 10:13 am