Advanced · Module 8 · Lesson 6 of 11
TCP State Machine and Socket Options: setsockopt, SO_REUSEADDR, and TIME_WAIT
Navigate the 11 states of the TCP lifecycle, eliminate bind failures using SO_REUSEADDR and SO_REUSEPORT, tune transmission latency with TCP_NODELAY, and manage TIME_WAIT drain states.
By the end you can
- Trace TCP state transitions across active close (FIN_WAIT, TIME_WAIT) and passive close (CLOSE_WAIT, LAST_ACK)
- Eliminate EADDRINUSE errors upon server restart using SO_REUSEADDR
- Distribute incoming connection queues across worker threads using kernel SO_REUSEPORT load balancing
- Disable Nagle's algorithm using TCP_NODELAY to minimize latency in request-response protocols
Builds on Connectionless Datagrams: UDP Sockets, Framing, and Packet Loss.
01 · A question first
Why does restarting a crashed web server immediately fail with "bind: Address already in use" even though no process is running, and why does sending small 10-byte packets over TCP incur unexpected 40-millisecond latency penalties?
Make a guess before you read on.
02 · The idea
Members only
Unlock the full lesson
This lesson is part of the membership. Join to read it in full, along with every other premium deep dive.
What's inside
- Start with the problem
- How the idea works
- Production Implementation: High-Throughput Server Setup
- Why it is correct
- What it costs
- Pitfalls and variations
- Where it is used
03 · Practice
Asked in interviews
Something wrong with this lesson? Report a problem