Don't Remember Panicking

A TC39 proposal for both

• A HostFaultHandler hook for optionally immediately terminating the enclosing unit of computation.
• A builtin panic method for explicitly invoking HostFaultHandler

Status

Achieved Stage 1 as OOM Must Fail-Fast

Co-Champions

• Mark S. Miller, Agoric (@erights)
• Peter Hoddie, Moddable (@phoddie)

Presentations

for stage 1 - October 2019 plenary - "OOM Must Fail-Fast" (video, pdf slides)

stage 1 update - April 2025 plenary - "Don't Remember Panicking" (keynote slides, pdf slides)

What

• A new Host Hook

HostFaultHandler(faultType, arg = undefined)

to be invoked for various from various internal fault conditions, so the host can react according to the host's policy. Including sudden termination of "Minimal Abortable Unit of Computation", such as an Agent cluster.

• A new built-in

Reflect.panic(arg = undefined)

so JavaScript code can directly fault to HostFaultHandler.

Why

See OOM Must Fail-Fast for the original motivation and rationale, most of which is still interesting and valid.

See "Don't Remember Panicking" Stage 1 Update (keynote slides, pdf slides) for the expanded motivation and rationale

Acknowledgements

Thanks to Felipe Natal for bring our attention to a problem that

• revived our interest in this old "OOM Must Fail Fast" proposal.
• needed the addition of a user panic operation to solve.