How to monitor golang gc

With the development of Go language, the garbage collection mechanism has become more and more mature. Go's garbage collection mechanism is accomplished by detecting memory reference counting. In some cases, garbage collection that is too frequent or too time-consuming can seriously affect application performance. Therefore, we need to monitor and optimize the garbage collection mechanism in the Go language. In this article, we will introduce how to use the Go language's own monitoring tools and third-party tools to monitor and optimize the garbage collection mechanism.

Monitoring tools that come with the Go language

The Go language provides developers with some very useful monitoring tools, which allow us to more easily monitor the running status of applications. Among these monitoring tools, the main ones related to garbage collection are as follows:

1. runtime/debug package

runtime/debug package provides some tools that can be used to check and runtime debugging information for debugging Go programs. Among them, the most commonly used function is FreeOSMemory(), which tells the garbage collector to try to reclaim the memory occupied by the operating system itself. This function is useful for applications that frequently use large amounts of memory. At the same time, the debug package also provides functions to obtain GC-related information:

• SetGCPercent(percent int) int: used to set the execution frequency of GC. The default value is $GOGC=100, which means garbage collection starts when the heap size increases by 100%. If you need more frequent garbage collection, you can set a smaller value, such as $GOGC=50.
• SetMaxStack(depth int) int: used to set the maximum stack depth.
• SetMaxThreads(num int) int: used to set the maximum number of threads in the Go program.
• ReadGCStats(stats *GCStats): used to obtain GC-related statistical information.

2. runtime/pprof package

The runtime/pprof package provides performance analysis tools for Go programs, which can help us identify bottlenecks and optimize them. Go language performance analysis tools can output files in different formats. Commonly used ones are:

• CPU Profiling: Displays CPU overhead;
• Heap Profiling: Displays heap space allocation status;
• Block Profiling: Shows the blocking situation;
• Goroutine Profiling: Shows the status of Goroutine (coroutine).

It is very convenient to use the pprof package to check GC-related indicators in Go programs, such as the following code:

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

func main() {
    // start web server to listen on localhost:8080
    go func() {
        http.ListenAndServe("localhost:8080", nil)
    }()

    // do something...

    // run heap profiling
    http.DefaultServeMux.HandleFunc("/debug/pprof/heap", func(w http.ResponseWriter, r *http.Request) {
        pprof.Lookup("heap").WriteTo(w, 2)
    })
}

3. log package

The log package is a package used for logging in the Go language standard library. When analyzing GC performance, we can use the log package to record the running history of the system. These logs can help us analyze the behavior of garbage collection, how to optimize the garbage collection mechanism, etc.

Third-party GC monitoring tools

In addition to the monitoring tools that come with the Go language, there are also some third-party tools that can help us better monitor, analyze and optimize GC-related situations. The following three tools are what we recommend:

1. Prometheus and Grafana

Prometheus is a tool for monitoring various applications, it can help collect various monitoring information and store it in a database, allowing for deeper analysis. Grafana provides data visualization tools to display various collected data more clearly. The following GC related metrics can be collected using Prometheus and Grafana:

##go_gc_duration_seconds
• go_gc_cpu_fraction
• go_gc_deltas_alloc_bytes
• go_gc_num_gc
• go_gc_pause_ns_avg
• go_gc_pause_ns_max
• go_gc_pause_ns_min
• go_gc_pause_ns_total

##net/http/pprof

2. Although in Go language This package has been mentioned in the built-in monitoring tool, but what we want to emphasize here is the summary information it provides, which can help us better understand the operation of GC, for example:

AllocSpace: memory allocation status;

• Heap: heap space allocation status;
• MSpan: off-heap memory allocation status;
• Scavenge: memory cleaning status;
• Sweep: Garbage collection information.

gopsutil

3. gopsutil is a Go language library used to collect system information. It can collect a large amount of system information, including CPU, memory, hard disk, network, etc. We can use the MemoryStat function in gopsutil to analyze system memory usage and see which programs or Goroutines are taking up too much memory.

Conclusion

During the development process, it is very important to monitor the garbage collection mechanism in the Go language. We can use the monitoring tools that come with the Go language, such as the debug package, pprof package, and log package. They provide some useful functions and interfaces to facilitate us to understand the behavior of the GC. In addition, we can also use some third-party tools, such as Prometheus, Grafana and gopsutil, which provide a more complete monitoring system and can provide us with more detailed data analysis and data visualization. In general, for the monitoring and optimization of garbage collection, it is necessary to start from multiple aspects and find the optimal GC strategy through continuous experiments and analysis to achieve the best application performance and stability.

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