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Fix async futex wait in WASM worker dose not keep runtime alive #20306

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Fix async futex wait in WASM worker dose not keep runtime alive #20306

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8 changes: 7 additions & 1 deletion src/library_wasm_worker.js
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Original file line number Diff line number Diff line change
Expand Up @@ -292,18 +292,24 @@ Atomics.waitAsync = (i32a, index, value, maxWaitMilliseconds) => {
$liveAtomicWaitAsyncs: '{}',
$liveAtomicWaitAsyncCounter: '0',

emscripten_atomic_wait_async__deps: ['$atomicWaitStates', '$liveAtomicWaitAsyncs', '$liveAtomicWaitAsyncCounter', '$jstoi_q'],
emscripten_atomic_wait_async__deps: ['$atomicWaitStates', '$liveAtomicWaitAsyncs', '$liveAtomicWaitAsyncCounter', '$jstoi_q',
#if !MINIMAL_RUNTIME
'$runtimeKeepalivePush', '$runtimeKeepalivePop',
#endif
Comment on lines +296 to +298
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I believe this is not needed. The compiler adds the runtime-keepalive stuff automatically.

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Unfortunately, after testing, the compiler does not automatically add runtime-keepalive stuff, because library_wasm_worker.js is not in the core system libraries of modules.js, so need to add a reference here manually.

emscripten/src/modules.js

Line 37 in f9ce05b

// Core system libraries (always linked against)

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Hmm, it's not in the core system libraries always linked against, but when you enable wasm workers then it is added to the list. And then it should be processed like any other library. That is, there should be no difference between a core library and a non-core library if both are linked in. Is that not so?

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Hmm, it's not in the core system libraries always linked against, but when you enable wasm workers then it is added to the list. And then it should be processed like any other library. That is, there should be no difference between a core library and a non-core library if both are linked in. Is that not so?

According to the modules.js, when enable WASM worker support, it doesn't seem to be automatically added to the core library.
As a result, dependencies must be added manually.

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Where do you see that? (I see no mention of wasm workers in modules.js)

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I think @kripken is right, we hopefully don't need these __deps here.. if you remove the __deps here what error do you see?

],
emscripten_atomic_wait_async: (addr, val, asyncWaitFinished, userData, maxWaitMilliseconds) => {
let wait = Atomics.waitAsync(HEAP32, {{{ getHeapOffset('addr', 'i32') }}}, val, maxWaitMilliseconds);
if (!wait.async) return atomicWaitStates.indexOf(wait.value);
// Increment waitAsync generation counter, account for wraparound in case
// application does huge amounts of waitAsyncs per second (not sure if
// possible?)
// Valid counterrange: 0...2^31-1
{{{ runtimeKeepalivePush() }}}
let counter = liveAtomicWaitAsyncCounter;
liveAtomicWaitAsyncCounter = Math.max(0, (liveAtomicWaitAsyncCounter+1)|0);
liveAtomicWaitAsyncs[counter] = addr;
wait.value.then((value) => {
{{{ runtimeKeepalivePop() }}}
if (liveAtomicWaitAsyncs[counter]) {
delete liveAtomicWaitAsyncs[counter];
{{{ makeDynCall('vpiip', 'asyncWaitFinished') }}}(addr, val, atomicWaitStates.indexOf(value), userData);
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