How to turn off gc in golang

When writing a program in the Go language, the automatic memory recycling mechanism is usually enabled, which is the garbage collection (Garbage Collection, GC) mechanism of the Go language. This mechanism allows us developers to write programs more conveniently, because there is no need to consider the issue of memory recycling and we can focus more on business implementation. However, sometimes we also face some special scenarios and need to manually turn off the GC to make the program run more efficiently.

Let’s take a look at why we need to turn off GC manually and how to turn it off?

1. Why do you need to turn off GC manually?

To address this problem, we need to start with the principle of the Go language’s automatic memory recycling mechanism. In the Go language, the essence of GC is to find inaccessible objects and recycle them to release memory. The triggering conditions of GC depend largely on the system's memory usage and GC parameter settings. For example, when the system memory usage exceeds a certain threshold, a GC operation can be triggered. If the GC operation reclaims more memory, the next GC trigger will be relatively delayed.

So, it is obvious that the frequency and execution efficiency of GC operations will directly affect the performance and response speed of the program. When a program needs to process a large amount of data and high concurrency scenarios, the frequency of GC will become more and more frequent, and at this time, the time taken by each GC operation will also become longer and longer.

In this case, if the automatic recycling mechanism of GC is still maintained, it will have a certain impact on the performance and response speed of the system. At the same time, it will also consume a certain amount of CPU computing resources and memory space, thereby reducing the actual efficiency of the program.

2. How to turn off GC?

Normally, we do not recommend turning off GC manually. Because the automatic memory recycling mechanism is still very important and necessary. However, in some scenarios, we do need to turn off the GC so that the program can execute more efficiently. The specific operations are as follows:

In Golang, you can use the GOGC environment variable in the runtime package to control the automatic recycling mechanism of GC. The default value of this variable is 100, which is the threshold value that triggers the memory recycling operation mentioned above. When we change the value of GOGC to 0, we can turn off the automatic memory recycling mechanism so that the program will no longer trigger GC operations.

There are two ways to modify GOGC:

The first is to write it directly in the source file of the Go code, as shown below:

package main

import "runtime"

func main() {
    runtime.SetGCPercent(-1)
    // 具体的业务逻辑
}

In the above code, we The SetGCPercent function provided by the runtime package is used to set the value of the GOGC environment variable. Since we want to turn off GC, we directly set the value of the setting to -1.

The second method is to set the value of the GOGC environment variable through command line parameters before the program is executed, as shown below:

$ env GOGC=-1 go run main.go

In the above code, we use the environment variable In this way, set the value of GOGC to -1 to turn off the GC mechanism.

It should be noted that after turning off the GC mechanism, the program will no longer have the ability to automatically reclaim memory, and all memory space will be managed by the program. Therefore, in actual use, it is necessary to consider accurately controlling memory usage to avoid memory leaks and memory overflows.

To sum up, turning off the GC mechanism is an extreme measure. Under normal circumstances, we do not need to manually turn off the GC. However, under special business scenarios and large data processing requirements, turning off the GC mechanism can significantly improve program performance.

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