Golang query takes up memory

Golang is an excellent programming language that is widely used in server application development and cloud computing. Memory usage is an issue that every application must consider. This article will introduce how to query the memory usage of a program in Golang.

1. Golang memory management

In Golang, memory management is implemented by the garbage collection mechanism. Programmers do not need to manually allocate and release memory. The compiler and runtime system will automatically manage memory, which greatly reduces the burden on developers.

Golang’s garbage collection algorithm uses a combination of mark-sweep algorithm and copy algorithm. When the runtime system detects the presence of an unreferenced object, it automatically marks it as a garbage object and clears it during subsequent garbage collection. In addition, Golang also puts small objects on the stack and uses a simple copy algorithm for recycling.

Sometimes, we need to query the memory usage of the program in order to better understand the performance and optimization needs of the program. Next, we will introduce how to use Golang to query the memory footprint of a program.

2. Golang memory query tool

1. pprof

pprof is a performance analysis tool provided by Golang. It can analyze the CPU usage and memory of the program. Occupancy is analyzed.

First, import the pprof package in the code:

import (
    "net/http"
    _ "net/http/pprof"
)

Then in the main function of the program, add the following code:

go func() {
    http.ListenAndServe("localhost:8080", nil)
}()

In this way, after the program starts, we The pprof tool can be used by accessing "http://localhost:8080/debug/pprof/".

We can enter "http://localhost:8080/debug/pprof/heap" in the browser to check the heap memory usage of the program, as shown in the following figure:

Finally, we can use the command line tool of go tool pprof to analyze the recorded data. For example, we can use the following command to view the functions that use the most memory in the program:

go tool pprof http://localhost:8080/debug/pprof/heap

2. runtime.MemStats

In addition to pprof, Golang also provides runtime. The MemStats type can be used to obtain the memory statistics of the program.

We can obtain the memory statistics information through the following code:

import (
    "runtime"
    "unsafe"
)

func getMemStats() runtime.MemStats {
    var mem runtime.MemStats
    runtime.ReadMemStats(&mem)
    return mem
}

By calling the getMemStats function, we can obtain the following memory statistics information:

• Alloc: Already The total amount of object memory allocated but not yet released, in bytes;
• TotalAlloc: the total amount of memory allocated by the system during runtime, in bytes;
• Sys: the program to The total amount of memory requested by the operating system, in bytes;
• NumGC: the number of garbage collections performed by the system during runtime;

We can use the following code to print the memory statistics of the program ：

mem := getMemStats()
fmt.Printf("Alloc: %v bytes
", mem.Alloc)
fmt.Printf("TotalAlloc: %v bytes
", mem.TotalAlloc)
fmt.Printf("Sys: %v bytes
", mem.Sys)
fmt.Printf("NumGC: %v
", mem.NumGC)

3. Memory usage optimization

Although Golang’s memory management is automated, programmers still need to consider the issue of memory usage. Here are some common memory usage optimization techniques:

1. Reduce memory fragmentation

Frequent memory allocation and release will lead to memory fragmentation and occupy too much memory. We can use sync.Pool to reuse some objects and reduce the generation of memory fragmentation.

2. Avoid using global variables

Global variables will always exist throughout the life cycle of the program and occupy a certain amount of memory. In order to reduce the memory footprint of the program, we should try to avoid using global variables and instead use local variables or share data through parameter passing.

3. Reduce memory copy

Memory copy is a major factor in occupying memory. We should try to avoid unnecessary memory copies, but avoid memory copies through pointers or slices.

4. Use streaming computing when processing large amounts of data

When processing large amounts of data, we should use streaming computing to avoid memory overflow. Streaming computing can calculate data in batches and output results, which is relatively more friendly in terms of memory usage.

5. Use of standard library

Golang’s standard library has provided some commonly used data structures and algorithm implementations. We can use the tools in the standard library to avoid duplication. Reinvent the wheel to reduce the amount of code and memory usage.

Summary:

This article introduces how to query the memory usage of a program in Golang. We can use the pprof tool for analysis, or we can obtain memory statistics through runtime.MemStats. In addition, this article also introduces some commonly used memory usage optimization techniques, which I hope will be helpful to everyone.

The above is the detailed content of Golang query takes up memory. For more information, please follow other related articles on the PHP Chinese website!