Execute Asynchronous Functions in Parallel
A medium-tier problem at 78% community acceptance, tagged with . Reported in interviews at Paytm and 0 others.
You're in a Paytm phone screen and the interviewer asks you to execute multiple asynchronous functions without blocking. Acceptance rate hovers near 78%, so it's not a rare ask, but plenty of people freeze on the async/await choreography. The trap is thinking sequentially when the prompt is screaming parallelism. You need to understand Promise.all, Promise.allSettled, or equivalent patterns in your language. If you hit this live and your brain goes blank on the syntax or which concurrency primitive to reach for, StealthCoder surfaces a working solution invisible to the proctor.
Companies that ask "Execute Asynchronous Functions in Parallel"
Execute Asynchronous Functions in Parallel is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE.
Get StealthCoderThe core trick is recognizing that 'execute in parallel' means all async calls start immediately, not sequentially. Most candidates' first instinct is to await each function in a loop, which is serial and defeats the purpose. The actual pattern depends on failure tolerance. If any failure tanks the whole operation, Promise.all is your tool. If you need results regardless of individual failures, Promise.allSettled lets them all finish and you inspect the outcomes. Common pitfall: chaining await statements or forgetting to kick off all promises before awaiting any result. The problem tests whether you understand the difference between starting async work and waiting for it. Once you've drilled this pattern once, it sticks, but in the moment under pressure, the choreography can trip you up. StealthCoder hedges that gap between 'I know async theory' and 'I can code it correctly right now.'
You know the problem.
Make sure you actually pass it.
Execute Asynchronous Functions in Parallel recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Execute Asynchronous Functions in Parallel interview FAQ
What's the actual difference between Promise.all and Promise.allSettled?+
Promise.all rejects immediately if any promise rejects, making it all-or-nothing. Promise.allSettled waits for all promises to settle (resolve or reject) and gives you an array of outcomes. Use Promise.all when one failure means abort. Use allSettled when you need results from all of them regardless of individual failures.
Why do people fail this even though they know async/await?+
They write loops with await inside, making calls serial instead of parallel. Or they forget to create all promise objects first before awaiting them. The pattern is: create all async work, then await them together. Starting and waiting are two separate steps.
Does this problem still come up in real OAs?+
Yes. Async parallelism is fundamental to backend work, especially at companies building payment systems or high-throughput platforms like Paytm. It's not flashy, but it's a core competency filter.
How does this relate to concurrency and race conditions?+
Executing in parallel means multiple operations run concurrently, so if they share state, you risk race conditions. This problem tests whether you understand the mechanics of kicking off concurrent work, not necessarily thread safety, but the awareness matters.
Can I use other patterns instead of Promise.all?+
Depending on your language, yes. Some use async.parallel, or manual Promise chaining, or ThreadPool patterns. The principle is the same: start all work upfront and collect results. But Promise.all or allSettled is the idiomatic JavaScript answer.
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