Thread-Local Variables in Ruby
Now this is probably not amazing news to long-time Ruby developers, but the simplicity and ease with which it's possible to make thread-local variables in Ruby is simply shocking. The ruby developers just don't know how good they have it. This morning I was looking at a threading problem with the CouchRest CouchDB client, and realized that it's not thread-safe. This isn't really shocking as thread-safety is something I've come to realize is not standard in Ruby libraries.
Still… I was determined to make it work.
What seemed logical was to have multiple database connections - one per thread, and then just have thread-local database connections. As the threads are born, they need a connection, create it, and use it. When they die, the connections are cleaned up automatically. Sweet. Simple.
But I know that dealing with thread-local storage in pthreads is not horrible, but it's certainly not "easy". I dig into the Ruby support for thread-local storage, and it's trivial:
Thread.current[:foo] = {}
This creates the tagged thread-local variable foo. How simple! This is something that I never expected to see. Never! So why are these Ruby guys having so much trouble with thread-safety? I have no idea.
With the tools I've seen in Ruby, there's really no excuse for why there aren't more thread-safe libraries. All the tools are there - they're just unused. Lazy coders.