Writing Correct Shut-Down Code is Hard

Graceful shutdown can be hard to get correct.

Examples

Imagine a system where a parent spawns child threads

• The parent waits for all to finish before it shuts down.

• What if one of the spawned threads is deadlocked?

• The parent will likely wait forever.

A similar system is instructed to shut down.

• The parent thread tells spawned child threads to abandon their tasks and finish.

• What if two children were operating as a producer/consumer pair?

• Producer receives the signal and shuts down.

• The consumer might be blocked waiting for the producer and is in a blocked state.

Recommendation:

Think about shut-down early and get it working early.

It's going to take longer than you expect.

Review existing algorithms because this is probably harder than you think.