Scheduler Fairness and Real-Time Performance: Golang vs Erlang

Overview

This codebase contains a comparative analysis of scheduling fairness and real-time performance between Golang and Erlang. Tests indicate that the performance of Golang’s goroutine scheduler is subpar — it is coarse, unfair, and lacks good real-time capabilities. In contrast, Erlang’s scheduler excels in both fairness and real-time performance!

Experimental Conclusions

Based on our rigorous testing:

Golang’s scheduler is implemented in a coarse manner, is clearly unfair, and has poor real-time performance
Erlang’s scheduler outperforms Golang significantly, demonstrating excellent fairness and real-time performance

Testing Methodology

Core Principles

The essence of scheduler evaluation lies in testing whether concurrent processes/goroutines are treated fairly, even when some routines are consuming significant CPU resources. Other routines should have equal execution opportunities, rather than being forced to delay or block.

Implementation Method

We designed two identical functions in both languages (work1 and work2), and then launched multiple resource-intensive routines (work_busy) to compete for system resources.

Explaining Performance Differences

While Golang (as a static language) naturally offers higher performance, we appropriately adjusted the number of routines for each language, work_busy to ensure:

Both implementations maintained a similar execution rate (approximately 60-80 executions per second)
work1 and work2 achieved roughly the same number of executions within the same time frame
The comparison primarily focused on scheduler behavior rather than raw language performance

Testing Environment and Versions

The tests were conducted using the following runtime versions:

Erlang/OTP: Version 27 [erts-15.0.1] [64-bit] [smp:16:16]
Golang: Version go1.25.0 windows/amd64

Platform Hardware and Operating System Environment:

Device: LAPTOP-H670TST5
Processor: 13th Gen Intel® Core™ i5-1340P (1.90 GHz)
Memory: 16.0 GB RAM
Operating System: Windows 11 Home Chinese Version (24H2)
OS Version: 26100.4946
Architecture: 64-bit operating system, x64-based processor

Starting Golang: Scheduler Fairness and Real-Time Performance: Golang vs Erlang Starting Erlang:

Results Analysis

After running approximately 10,000 iterations:

Golang Results:work1 executed work2 with a difference of over 100 executions
Erlang Results: only differing by 1 execution of – an astonishing result!work2

Golang results:

Scheduler Fairness and Real-Time Performance: Golang vs Erlang Erlang results:

Key Insights

Erlang’s scheduler demonstrates true soft real-time capabilities and achieves genuinely fair preemptive scheduling — aspects where Golang clearly falls short. The longer Golang runs in CPU-intensive environments, work1 and work2 diverge even more.

Conclusion

This comparison reveals fundamental differences in scheduler design philosophies. Erlang’s proven process scheduler is designed for telecom-grade reliability, showcasing superior fairness and real-time performance compared to Golang’s newer goroutine scheduler, especially under sustained CPU pressure.