Fan out work to background processes and wait for them all.
Concurrent HTTP requests with asyncio.gather and aiohttp.
ThreadPoolExecutor fan-out for I/O-bound work.
Issue several HTTP requests in parallel with Promise.all.
Wait for a batch of goroutines using sync.WaitGroup.
Fan-in pattern: workers push results onto a channel.
Share a counter across threads with Arc>.
Run concurrent async tasks with tokio::spawn and join.
Use std::thread::spawn and join handles for parallel work.
Fan out HTTP calls across threads and join them.