Hi, does anyone know why launching many concurrent...

# javascript

[Luca]

Hi, does anyone know why launching many concurrent operations/api calls with coroutines would be 3x-4x slower in firefox vs chrome?

something along the lines of this:

coroutineScope {
    storeListItems.forEachIndexed { i, item ->
        launch(Dispatchers.Default) {
            val price = api.getPurchasePrice(item.id)
            storeListItems[i] = StoreListItem(item, price)
            stateManager.updateScreen(StoreListState::class) {
                it.copy(
                    storeListItems = storeListItems,
                )
            }
        }
    }
}

where I have to fetch the prices of many store items with a separate api call for each store item by their id.

Additionally, chrome will update the screen as I expect (the order in which the prices get updated happens progressively) while firefox doesn’t seem to be handling the concurrency correctly and it updates the screen all at once)

[Sergei Grishchenko]

As far I see it you are sending your requests subsequently (not concurrently). It seems you need something like api.getPurchasePriceAsync(item.id) that returns Async<T> or Promise<T> and you need to .await() them all after forEachIndexed or mapIndexed at once.

[Sergei Grishchenko]

There is also awaitAll helper for such tasks.

[Luca]

That’s not the issue. It is being launched concurrently. launch does not block @Sergei Grishchenko