ESM resolution and loading is now always synchronous from a
non-loader-hook thread. If no asynchrnous loader hooks are
registered, the resolution/loading is entirely synchronous.
If asynchronous loader hooks are registered, these would be
synchronous on the non-loader-hook thread, and asynchronous
on the loader hook thread.
This avoids several races caused by async/sync loading sharing
the same cache. In particular, asynchronous loader hooks
now works with `require(esm)` - previously it tends to break
due to races.
In addition, when an asynchronous loader hook
returns a promise that never settles, the main thread no longer
silently exits with exit code 13, leaving the code below
any module loading calls silently ignored without being executed.
Instead, it now throws ERR_ASYNC_LOADER_REQUEST_NEVER_SETTLED
which can be caught and handled by the main thread. If the module
request comes from `import()`, the never-settling promise is
now relayed to the result returned by `import()`.
Drive-by: when annotating the error about importing undetectable
named exports from CommonJS, it now no longer reload the source
code of the CommonJS module, and instead reuses format information
cached when the module was loaded for linking.
PR-URL: https://github.com/nodejs/node/pull/60380
Fixes: https://github.com/nodejs/node/issues/59666
Reviewed-By: Geoffrey Booth <webadmin@geoffreybooth.com>
Reviewed-By: Jacob Smith <jacob@frende.me>
The modules located in lib/internal directory are exclusively meant
for internal usage within the Node.js core. They are not intended to
be accessed via user modules require(). These modules may change at
any point in time. Relying on these internal modules outside the core
is not supported and can lead to unpredictable behavior.
In certain scenarios, accessing these internal modules for debugging or
experimental purposes might be necessary. Node.js provides the --expose-internals
flag to expose these modules to userland code. This flag only exists to
assist Node.js maintainers with debugging internals. It is not meant for
use outside the project.
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