Blog · page 4
Notes on engineering, design, and everything in between.
Graceful shutdown: the exit sequence decides between 502s and clean responses
Exiting immediately on a termination signal cuts in-flight requests. The order is stop accepting, drain what is running, release resources, then exit.
HTTP caching: Cache-Control and ETag each own half
Cache-Control decides whether a request happens; ETag decides whether the response body can be skipped. Mixing them is why cache bugs persist: changing one never fixes the other half.
Idempotency keys: the one write that makes retries safe
A network timeout does not mean the server did nothing. An idempotency key identifies the same request so the server replays the first result instead of executing again.
JSON canonicalization: why the same object hashes two ways
Key order, number formatting and escape style all change the bytes. A stable hash has to pin those rules at serialization, not hope JSON.stringify is deterministic.
Memory layout: the same algorithm, ten times slower, is usually cache
A trip to main memory costs hundreds of cycles; a cache line fetch costs one. Sequential versus random access often outweighs the algorithmic order itself.
Deadlock: break any one of four conditions
Mutual exclusion, hold and wait, no preemption, circular wait. All four must hold at once. The practical one to break is circular wait: give every lock a global order.