`onRuntimeInitialized` no longer being called

[jeswr]

As of v4 it appears that onRuntimeInitialized is no longer invoked after initialising a module.

Is this expected behavior?

Observed in SWI-Prolog/swipl-devel#1343 (comment)

[sbc100]

No that is not intended. We do have quite a few test for onRuntimeInitialized (spelt with a z BTW) so something odd must be going on.

Can you confirm that version in which this stopped working for you? Was it 4.0.0 exactly? Did it work in the previous version (3.1.74)?

[jeswr]

Yes, 4.0.0 exactly. You can see:

• CI passing on our main branch with 3.1.74 https://github.com/SWI-Prolog/npm-swipl-wasm/blob/8fb115d24e77188df30cd28f3cd566bf49d04b45/package.json#L83-L87
• CI failing on this automated PR bumping to 4.0.0 BREAKING CHANGE: update to emsdk v4.0.0 SWI-Prolog/npm-swipl-wasm#837 and the same error occuring when trying to bump to 4.0.3 BREAKING CHANGE: update to emsdk v4.0.3 SWI-Prolog/npm-swipl-wasm#861
• The error is fixed when manually calling Module.onRuntimeInitialized(); after initialising the module in https://github.com/SWI-Prolog/npm-swipl-wasm/pull/863/files

The implementation of onRuntimeInitialized is upstream at https://github.com/SWI-Prolog/swipl-devel/blob/5f00677154dfcde00381fdaf501d72d2b985008d/src/wasm/prolog.js#L1919-L1921 (and uses z)

[sbc100]

Can you share the full list of linker flags that you use? Are you using -sSTRICT by any chance?

[jeswr]

I don't believe so this is the CMAKE file used @JanWielemaker would be the one who can confirm this.

[jeswr]

Specifically these are the linker flags used

[sbc100]

Can you show me how/where you inject your onRuntimeInitialized call? If you are adding it in a --post-js file that might explain the issue. We switch to using async/await during initialization in #23157. See the changelog entry from that change:

emscripten/ChangeLog.md

Lines 109 to 114 in 242af00

	- The factory function exposed in `-sMODULARIZE` mode is now marked as `async`
	when `WASM_ASYNC_COMPILATION` is enabled (the default). This allows us to use
	`await` during module creation. One side effect of this is that code in
	`--post-js` files will now be delayed until after module creation and after
	`main` runs. This matches the existing behaviour when using sync instantation
	(`-sWASM_ASYNC_COMPILATION=0`) but is an observable difference. (#23157)

I don't see any --post-js flag, but I suspect this is somehow the reason. Somebody else also reported a similar issue: #23420.

One thing I was think of doing is adding an assertion if these things are added to the Module too late..

[jeswr]

Aha thankyou! Looks like @JanWielemaker very recently converted --pre-js to --post-js in SWI-Prolog/swipl-devel@abec205; more recently than the release of v4.0.3.

Updating to include those changes indeed fixes things.

One thing I was think of doing is adding an assertion if these things are added to the Module too late..

Yes, I think this would be useful

[JanWielemaker]

converted --pre-js to --post-js in SWI-Prolog/swipl-devel@abec205; more recently than the release of v4.0.3.

Nope. It is the other way around. There used to be --pre-js and --post-js code. These two files have been merged and are used as--pre-js. So far that seems fine.

I think you should be able to update to 9.3.20. If you want to replicate my build

• create ~/wasm
• Install Emscripten in ~/wasm/emsdk
• Build the zlib and pcre2 libs such that they are installed with prefix ~/wasm
• create a build dir in SWI-Prolog called build.wasm
• In this dir, run ../scripts/configure. This creates, based on the build dir name, a script configure that sets the necessary environment and runs cmake.

[jeswr]

I think you should be able to update to 9.3.20

Have done - new version of swipl-wasm now released https://github.com/swI-Prolog/npm-swipl-wasm. Thanks for making the fix 🥳