[Migrated] Multiple keep warm

[jneves]

Originally from: Miserlou/Zappa#861 by mcrowson

Description

The keep_warm setting now takes an integer for the number of concurrent containers to keep warm. This is done by the keep_warm_callback in the handler.py file using a thred pool to call zappa async tasks that each initialize the application.

Those initialized applications then wait 30 seconds before returning to allow for other other lambdas to cold start rather than reuse the newly warmed container.

Somewhat arbitrary values were set for the ThreadPool size and the sleep size. If the user has specified a timeout_seconds < 30, it will exit sooner.

The time to run the keep_warm_callback with 200 as the value was 15 seconds. If the time.sleep is too low, then it is possible for some percentage of the keep_warm_lambda_initializers to use warm containers.

GitHub Issues

#851