Tell about concurrent processing — how did you limit parallelism, how did you select parameters based on measurements?

In Go, semaphores or buffered channels are often used to limit parallelism, which restrict the number of goroutines running simultaneously. For example, a channel with a buffer equal to the maximum number of parallel tasks is created, and before starting a goroutine, a value is sent into it, and upon completion, it is received from, thereby controlling the number of active goroutines.

Parameter selection (such as pool size or number of parallel tasks) is usually based on performance and load measurements. Response time, CPU usage, memory, and throughput are measured. If parallelism is too low, the system idles; if too high, resource contention occurs, leading to increased delays and possible errors.

An example of limiting parallelism using a channel:

sem := make(chan struct{}, maxParallelism)

for _, task := range tasks {
    sem <- struct{}{} // blocks if limit is reached
    go func(t Task) {
        defer func() { <-sem }() // release slot
        process(t)
    }(task)
}

// wait for all goroutines to finish
for i := 0; i < maxParallelism; i++ {
    sem <- struct{}{}
}

Thus, you can flexibly manage parallelism and select optimal parameters based on load testing results.