Accessing a thread's module instance in an -sMODULARIZE -pthread setting?

[Stephan Bergmann]

When I use -sMODULARIZE and -pthread, code gets generated into the *.js
file so that the pthread workers do

> isPthread && Module();

(where the Module() invocation returns a promise that resolves to a
module instance). But that module instance is effectively "lost", or is
there some way for me to obtain it? (Other than using sed on the
generated *.js to make that line instead read

> isPthread && createOnlineModule().then(module => ...);

and capture the instance.)

[Sam Clegg]

Yes, the "module" object in this case is internal to the thread only.    No code other than emscripten-generted code ever runs in a pthread worker so hopefully there is no external code that might need it.

All internal code such as EM_ASM and js-library functions all run in the module scope so have access to all the module instance internals already.  Anything you would access have `MyModule.foo` can be accessed simply via `foo` in internal code (this goes for single threaded code too).

cheers,

sam

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[Stephan Bergmann]

On 7/22/25 20:48, 'Sam Clegg' via emscripten-discuss wrote:
> Yes, the "module" object in this case is internal to the thread only.
> No code other than emscripten-generted code ever runs in a pthread
> worker so hopefully there is no external code that might need it.

unless code gets loaded via WorkerGlobalScope.importScripts (as is e.g.
done at
<https://git.libreoffice.org/core/+/5dbc995f73da45ad99b95bc3119c75451b2c415d/desktop/source/app/appinit.cxx#78>)

> All internal code such as EM_ASM and js-library functions all run in the
> module scope so have access to all the module instance internals
> already.  Anything you would access have `MyModule.foo` can be accessed
> simply via `foo` in internal code (this goes for single threaded code too).
>
> cheers,
> sam
>
> On Thu, Jul 17, 2025 at 7:37 AM Stephan Bergmann <sber...@gmail.com
> <mailto:sber...@gmail.com>> wrote:
>
> When I use -sMODULARIZE and -pthread, code gets generated into the *.js
> file so that the pthread workers do
>
> > isPthread && Module();
>
> (where the Module() invocation returns a promise that resolves to a
> module instance).  But that module instance is effectively "lost",
> or is
> there some way for me to obtain it?  (Other than using sed on the
> generated *.js to make that line instead read
>
> > isPthread && createOnlineModule().then(module => ...);
>
> and capture the instance.)
>
> --
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> To view this discussion visit https://groups.google.com/d/msgid/
> emscripten-discuss/c7ce1e8e-2f14-4739-a1f2-5598133ad270%40gmail.com

> <https://groups.google.com/d/msgid/emscripten-discuss/
> c7ce1e8e-2f14-4739-a1f2-5598133ad270%40gmail.com>.

[Sam Clegg]

On Wed, Jul 23, 2025 at 2:43 AM Stephan Bergmann <sber...@gmail.com> wrote:

On 7/22/25 20:48, 'Sam Clegg' via emscripten-discuss wrote:
> Yes, the "module" object in this case is internal to the thread only.   
> No code other than emscripten-generted code ever runs in a pthread
> worker so hopefully there is no external code that might need it.

unless code gets loaded via WorkerGlobalScope.importScripts (as is e.g.
done at
<https://git.libreoffice.org/core/+/5dbc995f73da45ad99b95bc3119c75451b2c415d/desktop/source/app/appinit.cxx#78>)

I think you could try something like this your JS code right before the call to `importScripts`:  `globaThis.Module ||= Module`.

Then the imported code would have access to the `Module` object. 

cheers,

sam
 

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[Stephan Bergmann]

On 7/24/25 01:14, 'Sam Clegg' via emscripten-discuss wrote:
> I think you could try something like this your JS code right before the
> call to `importScripts`:  `globaThis.Module ||= Module`.

oh yes, sure, thanks! :)