Detailed explanation of golang memory recycling strategy

Abstract: Go language uses mark-sweep algorithm for memory recycling. Strategies include generational GC, escape analysis, concurrent mark and Finalizer. In actual combat, you can use the runtime/debug package to monitor memory usage, such as SetGCPercent() to set the GC frequency, and ReadGCStats() to obtain GC statistics.

Detailed analysis of Go language memory recycling strategy

In the Go language, memory recycling (Garbage Collection, GC) is done through a method called "mark- "Clear" algorithm is implemented. The algorithm is executed in the following steps:

1. Marking phase

GC will traverse all live objects (objects accessible through references or pointers) and mark them To survive.

2. Cleanup phase

GC will clear all unmarked objects and release the memory space they occupy.

Go's memory recycling strategy

The Go language provides a variety of memory recycling strategies to optimize GC performance:

1. Generational GC

• Newly created objects will be allocated in the lower generation and have a shorter survival time.
• As objects survive longer, they will be promoted to higher generations.
• Lower generation GCs occur more frequently, while higher generation GCs occur less frequently.

2. Escape analysis

• Escape analysis can determine whether an object can escape outside its creation function.
• If the object cannot escape, it will be allocated on the stack instead of the heap, thus avoiding GC.

3. Concurrent marking

• Go version 1.8 introduces a concurrent marking phase, which can improve GC performance.
• Multiple Goroutines mark objects in parallel, thereby reducing marking time.

4. Finalizer

• Finalizer is the destructor, which is automatically called when the object is recycled by GC.
• Finalizer can be used to clean up external resources (such as closing files), but should be used with caution to avoid affecting GC performance.

Practical case: Using the runtime/debug package

runtime/debug package provides the following two functions to debug memory usage :

• SetGCPercent(percent int): Set the frequency of GC occurrence.
• ReadGCStats(stats *GCStats): Get a pointer about GC statistics.

The following is a practical case demonstrating how to use the runtime/debug package to monitor memory usage:

package main

import (
    "bytes"
    "fmt"
    "runtime"
    "runtime/debug"
)

func main() {
    var buff bytes.Buffer
    debug.SetGCPercent(20)

    for i := 0; i < 10000; i++ {
        // 创建一个很大的对象
        b := make([]byte, 1000000)

        // 记录 GC 统计信息
        stats := new(debug.GCStats)
        debug.ReadGCStats(stats)
        fmt.Fprintf(&buff, "GC 次数：%d\n", stats.NumGC)
        fmt.Fprintf(&buff, "上次 GC 后存活的对象数量：%d\n", stats.PauseTotal)
    }

    fmt.Println(buff.String())
}

By running this program, you can observe GC occurrences frequency and number of surviving objects. This will help you understand the GC behavior of the Go language and optimize your program's memory usage.

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