Async version is not async

[addaleax]

This is not an asynchronous call (and does throw an exception in the current node.js master):

setTimeout(__calculate(), 0);

You could use setTimeout(__calculate, 0);, but recursive setTimeout calls are slowed down (to avoid tasks hogging the CPU, I assume), which leads to timeouts in the test cases. Maybe just go for setImmediate or similar here?

[addaleax]

(The exception in node.js is due to nodejs/node#4362, with the very purpose of catching bugs like this)

[hiddentao]

Thanks, I'm surprised I didn't notice that before - that was totally wrong. That's now fixed. I've also set it so that it will use process.nextTick() instead if available.