CommonOptions.childProcess property

If true, create a child process to isolate user code from faast scaffolding. Default: true.

Signature:

childProcess?: boolean;

Remarks

If a child process is not created, faast runs in the same node instance as the user code and may not execute in a timely fashion because user code may block the event loop. Creating a child process for user code allows faast.js to continue executing even if user code never yields. This provides better reliability and functionality:

Detect timeout errors more reliably, even if the function doesn't relinquish the CPU. Not applicable to AWS, which sends separate failure messages in case of timeout. See CommonOptions.timeout.
CPU metrics used for detecting invocations with high latency, which can be used for automatically retrying calls to reduce tail latency.

The cost of creating a child process is mainly in the memory overhead of creating another node process.