Rejection on createComputePipelineAsnyc causes timout in tests

[sagudev]

this happens because rejection is not handled. Example:

cts/src/webgpu/shader/execution/expression/expression.ts

Line 1179 in 85678b2

const pipeline = await t.device.createComputePipelineAsync({

(there are more such places).

You can see live example here: https://sagudev.github.io/cts/standalone/?runnow=1&q=webgpu:shader,execution,expression,binary,f32_subtraction:scalar_vector:inputSource=%22const%22;* which has rejection hard-coded sagudev@615b943 (reproducible on Edge).

This is problem in servo because some things are not supported yet (so promise does reject).

[sagudev]

related #3157

[kainino0x]

Thanks for the report, definitely something going wrong here.

Because the promise is created before it's awaited, this is causing an unhandledrejection (see #3159). I don't know why that results in a hang, though - the intent was that it would eventually reach the await Promise.all(pendingBatches) line and the test should fail.

[sagudev]

It looks like that we never reach await Promise.all(pendingBatches) on rejection, because if (batchesInFlight > maxBatchesInFlight) { happens. I think the main reason hang happens is because void t.queue.onSubmittedWorkDone().finally(batchFinishedCallback); is never called when const checkBatch = await submitBatch(t, shaderBuilder, shaderBuilderParams, pipelineCache); rejects.

[sagudev]

So the timeout was caused by never resolving

cts/src/webgpu/shader/execution/expression/expression.ts

Line 428 in f752c75

resolvePromiseBlockingBatch = resolve;

as batchFinishedCallback was never called, due to rejection on

cts/src/webgpu/shader/execution/expression/expression.ts

Line 414 in f752c75

const checkBatch = await submitBatch(t, shaderBuilder, shaderBuilderParams, pipelineCache);

the solution is to move the callback to

cts/src/webgpu/shader/execution/expression/expression.ts

Line 433 in f752c75

pendingBatches.push(processBatch(batchCases));

(and it also belongs there conceptually, as it only deals with decreasing batchesInFlight); see #3844.

[sagudev]

Fixed in #3844.