Why Aren't My Go Goroutines Running in Parallel?

Why Doesn't the Go Runtime Execute Concurrent Statements in Parallel?

Question:

I am running a Go program that is not utilizing multiple CPU cores despite having access to them. I am using goroutines to perform concurrent tasks, but they are executing sequentially. What could be causing this behavior?

Answer:

There are two possible explanations for this issue:

• GOMAXPROCS environment variable: The GOMAXPROCS variable controls the number of CPUs that the Go runtime is allowed to use. By default, this variable is set to 1, which means that the runtime will use only a single CPU. To enable parallel processing, you need to set GOMAXPROCS to a value greater than 1. You can do this either by setting the environment variable or using the runtime.GOMAXPROCS function in your code.
• Channel communication: If your goroutines spend a significant amount of time communicating with each other through channels, using multiple CPU cores may actually hinder performance. This is because channel communication involves context switching, which can add overhead. In such cases, it is more efficient to use a single CPU core for all goroutines.

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