async/await improvements

C. Scott Ananian ecmascript at cscott.net
Wed Nov 12 07:13:46 PST 2014


I think you're missing the point: you need to solve the halting problem if
you expect to get prompt notification of asynchronous exceptions.  This
can't be solved at a language level. The only solution is to expose the
pending unhandled exceptions to programmers so that they can use their
human judgment to determine when the exception has been pending "long
enough" that it's actually an error. (And this isn't a new issue, or
specific to promises or await/async.)

GC of an promise tells you that some async exceptions can no longer be
handled, but that's only part of the iceberg.  Promises can also be kept
live indefinitely with unhandled exceptions.  That's not necessarily an
error -- perhaps a handler will eventually be added.  Like I said, you need
to solve the halting problem if you want to definitely identified unhandled
asynchronous exceptions. The best solution is to expose the pending
exceptions to the human, and let them decide.

Please go back and reread the extensive discussions we've had on this topic
previously on this mailing list.  I'm writing from my phone, but perhaps
someone better connected can give you a few URLs.
  --scott
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