Why you should understand (a little) about TCP - Julia Evans

Why you should understand (a little) about TCP - Julia Evans

Nov 21st, 2015 This isn't about understanding everything about TCP or reading through TCP/IP Illustrated . It's about how a little bit of TCP knowledge is essential. Here's why. A year later, at work, someone mentioned on Slack "hey I'm publishing messages to NSQ and it's taking 40ms each time". I'd already been thinking about this problem on and off for a week, and hadn't gotten anywhere. A little background: NSQ is a queue that you send to messages to. The way you publish a message is to make an HTTP request on localhost. It really should not take 40 milliseconds to send a HTTP request to localhost. Something was terribly wrong. The NSQ daemon wasn't under high CPU load, it wasn't using a lot of memory, it didn't seem to be a garbage collection pause. Help. Then I remembered an article I'd read a week before called In search of performance - how we shaved 200ms off every POST request . In that article,

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