How to benchmark in Go?

The Go language is an efficient, strongly typed, concurrency-safe programming language that focuses on high performance and efficiency from the beginning of its design. Benchmark testing is one of the methods used in the Go language to test code performance and efficiency.

In this article, we will introduce the concepts and goals of benchmarking, and then explain how to use Go’s built-in testing package to conduct benchmarking.

What is a benchmark test?

Benchmark testing is a method used to test the performance of a program to determine the performance and speed of a code or algorithm. Usually, in order to write high-performance code, we need to optimize algorithms and data structures. However, if we don't have a way to evaluate performance, then we may not know which method is superior.

Benchmarking is a method of quantifying and evaluating code performance. By writing test codes and running them repeatedly, observe the speed and efficiency of code execution in the test results. This helps us optimize our code for better performance.

What is the goal?

The main goal of benchmarking is to determine the performance of a set of code. Often, this set of code will use different algorithms or data structures to achieve the same result. Benchmarks can help us determine which algorithm or data structure is the most efficient to achieve better performance.

Another goal is to identify defects and bottlenecks in the code. In testing, we can see how long and how fast the code executes to understand possible problems in the code. By identifying issues and bottlenecks, we can further optimize the code and algorithms for better performance.

Benchmarking using Go’s built-in testing package

Go’s built-in testing package provides functionality for writing benchmark tests. The testing package supports combining test code with benchmarks and performance tests. We can use testing.B to write and run benchmarks. testing.B is a subset of testing.T, which is a structure representing a benchmark test.

To write a benchmark test, follow these steps:

1. Create the test function in the _test.go file

Tests must be prefixed with Benchmark At the beginning, followed by the name of the test function, the Test prefix cannot be used. This function must accept a parameter of type *testing.B.

Strictly speaking, the routine format is: func BenchmarkXxx(*testing.B), where Xxx can be the function name, example: BenchmarkHello.

For example:

func BenchmarkMyFunction(b *testing.B) { for n := 0; n < b.N; n++ { // Call the function you want to benchmark myFunction() } }

In this example, we benchmark the myFunction() function and run it b.N times using a for loop.

2. Running the Benchmark

To run the benchmark, use the go test command with the -bench flag. The -bench flag is followed by a regular expression indicating which benchmarks to run.

For example:

go test -bench=.

This will run benchmarks that match all benchmark names in the current directory. You can also pass a package name as an argument to go test to run only the benchmarks in that package.

3. Analyze test results

go test will output the test results on the console. The output includes the name of each test, the number of executions, and the total time. The format of the output result is:

BenchmarkMyFunction 1000000 97.9 ns/op

where BenchmarkMyFunction is the name of the test, 1000000 is the number of test runs, and 97.9 ns/op is the average time (nanoseconds) of each operation.

The test results may change due to the influence of other running programs, so it is recommended to run the test multiple times to obtain more accurate results.

Summary

Go benchmarking is a method for quantifying and evaluating code performance. Writing and running benchmarks is easy using Go's built-in testing package. Benchmarking can help us determine which algorithm or data structure is the most efficient and identify possible problems and bottlenecks in the code. Ultimately, through benchmark optimization, we can achieve better code performance and efficiency.

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