runtimeGOMAXPROCS4

runtimeGOMAXPROCS4 is a naming convention used in some Go projects to configure the Go runtime to allow at most four operating-system threads executing Go code concurrently. It is not a standard feature name in the Go language itself; rather, it is a project-specific label for a startup-time configuration that calls runtime.GOMAXPROCS(4).

The purpose is to bound the level of parallelism in the Go runtime. By setting GOMAXPROCS to 4, a program limits the number of OS threads that can execute Go code at the same time. This can improve predictability and resource usage on hardware with limited cores or in environments with strict CPU quotas, while still allowing the scheduler to multiplex goroutines across those threads.

Usage typically occurs during initialization, such as in main or an init function, by invoking the runtime.GOMAXPROCS function with the value 4. The effect applies to the entire process. Goroutines may still move between threads, and I/O-bound workloads may not require additional parallelism—CPU-bound workloads could see reduced throughput if more CPUs are available.

Considerations include the fact that modern Go defaults often align GOMAXPROCS with available CPU resources or container-imposed quotas. In multi-core environments, fixing the value to four may underutilize hardware. When using containers, it is important to align GOMAXPROCS with the container’s CPU limit and expected workload.

Alternatives include environment-based configuration or dynamic adjustments at runtime. The official API is runtime.GOMAXPROCS, which accepts an int and returns the previous limit.