Unverified Commit 92d7e81b authored by Trevor Norris's avatar Trevor Norris
Browse files

src: clear async id stack if bootstrap throws

If bootstrap throws and if ids are added to the async id stack and if
the exception wasn't handled by the fatal exception handler then the
AsyncCallbackScope destructor will cause the AsyncHooks::pop_ids() stack
check to fail. Causing the application to crash. So clear the async id
stack manually.

This is only possible if the user: 1) manually calls MakeCallback() or
2) uses async await in the top level. Which will cause _tickCallback()
to fire before bootstrap finishes executing.

The following example shows how the application can fail due to
exceeding the maximum call stack while using async await:

    async function fn() {
      fn();
      throw new Error();
    }
    (async function() { await fn(); })();

If this occurs during bootstrap then the application will pring the
following warning a number of times then exit with a status of 0:

    (node:*) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: *): Error

Here's the same recursive call done after enabling a new AsyncHook() the
following will print instead of the above warning and exit with a
non-zero code (currently it's 7 because of how node::FatalException
assigns error codes based on where the failure happened):

    script.js:25
    async function fn() {
                     ^
    RangeError: Maximum call stack size exceeded
        at <anonymous>
        at fn (script.js:25:18)
        at fn (script.js:26:3)
        ....

This has to do with how Promises lazily enable PromiseHook if an
AsyncHook() is enabled. Whether these need to be made uniform is outside
the scope of this commit

Fixes: https://github.com/nodejs/node/issues/15448
PR-URL: https://github.com/nodejs/node/pull/15553


Reviewed-By: default avatarAnna Henningsen <anna@addaleax.net>
Reviewed-By: default avatarJames M Snell <jasnell@gmail.com>
Reviewed-By: default avatarRefael Ackermann <refack@gmail.com>
parent 8a6f376e
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