Why are Ab and Wrk Benchmarks so Different for Go HTTP Servers?

Go HTTP Server Performance: Differences Between ab and wrk Benchmarks

Problem Statement:

When benchmarking a Go HTTP server using both ab and wrk, significant discrepancies in performance measurements were observed, leaving the user puzzled as to the reason behind the vast differences.

Analysis:

Factors Affecting Benchmark Accuracy:

• Artificiality of Benchmarks: Real-world applications introduce additional factors like database calls and session parsing, leading to lower performance compared to simple "Hello World" responses.
• Local Machine Limitations: Resource constraints, loopback adapters, and TCP stack tuning can impact benchmark results.

Specific Differences Between ab and wrk:

• HTTP Version: ab uses HTTP/1.0 and does not support keepalives, while wrk supports HTTP/1.1 and keepalives.
• Latency: The latency reported by ab was significantly higher than that reported by wrk.
• Duration: The ab test ran for 12 seconds, while the wrk test ran for 5 seconds.
• Load Generation: wrk is generally considered a more reliable benchmarking tool and has the ability to generate higher load than ab.

Recommendations:

• Use wrk for more accurate and representative benchmarks.
• Keep in mind the limitations and variances inherent in benchmarking tools.
• Focus on optimizing the server code and understanding resource utilization rather than chasing specific performance figures.
• Benchmarks should be conducted under realistic scenarios with actual workloads.

Scaling with More Cores:

The scaling capabilities of a Go HTTP server with additional cores depend on the specific workload. Single-threaded operations, such as responding with a simple "Hello World" message, show linear scaling. However, for more complex workloads, scaling may become nonlinear due to contention for shared resources or other factors.

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