How to optimize golang gc

As more and more applications use golang as the back-end programming language, the need for golang's GC performance has become increasingly important. The automatic garbage collection of Go language is one of its most distinctive features, but for some scenarios that require high performance and low latency, GC performance may become a bottleneck. This article will introduce how to optimize the performance of golang gc and optimize performance.

1. Understand the GC mechanism

Understanding the GC mechanism is the first step to optimize GC performance. The GO language uses a three-color marking method garbage collection algorithm. This algorithm uses concurrent marking and cleans up after the scanning is completed, which means that there may be some price to pay in terms of performance.

1) GC time-consuming

During the garbage collection cycle, all goroutines must stop running so that the garbage collector can clear as much memory as possible. GC will bring some significant delays, and most of the GC time is concentrated in the marking phase. The larger the heap space, the longer the GC time will be.

2) The impact of heap size on GC

The GC mechanism of Go language is a mark and clear algorithm, which runs when all goroutines (threads) cannot execute, while ensuring that the program runs smoothly. Leaks will occur, and a little carelessness can cause some significant performance issues.

Each program has a heap size, which is controlled through the two environment variables runtime.GOMAXPROCS and runtime.GOGC. runtime.GOGC defaults to 100, which means that when 100% of available memory is reached, the GC will start automatically performing garbage collection while the program is running. The runtime.GOMAXPROCS controls the maximum number of goroutines during program concurrency.

3) GC Algorithm

The main advantage of Go language using the three-color marking algorithm is that it can clean up the entire heap in a short time, avoiding unnecessary cleaning operations. The three-color marking algorithm has minimal pause time and the ability to clean the heap in real time, however, it requires very high memory scanning performance. This is due to the fact that the algorithm needs to perform read and write operations on the object. So we need to balance memory usage with minimum pause time.

2.GC optimization skills

After understanding the GC mechanism, we can optimize GC performance through some methods. There are several methods:

1) Concurrent GC

Concurrent GC means that the application can still continue to execute before the GC starts. The GC of Go language only runs when the program cannot continue execution. Also, because the program is not working during garbage collection, concurrent garbage collection can greatly reduce the time the program is down.

2) Non-aligned memory allocation

Non-aligned memory allocation refers to applying for non-aligned memory blocks on the heap. This is a way to reduce memory fragmentation. Memory fragmentation refers to the gaps between multiple memory blocks. Usually, when using a heap manager to manage memory, garbage collection requires moving and adjusting different memory blocks in the heap, which results in a large number of memory copies. If fragmentation can be reduced, GC will be more efficient.

3) Manually triggering GC

Manually triggering GC means explicitly calling the runtime.GC function during the running of the program. While this is not the most radical solution, it can effectively reduce GC latency.

4) Adjust GOGC

Running GC during the peak period of the program may have a serious impact on performance. The value of runtime.GOGC can be appropriately adjusted to reduce the frequency of GC. This variable should be adjusted appropriately according to the application's workload and memory usage pattern.

5) Avoid using GC

By avoiding unnecessary dynamic memory allocation and release in the program, the frequency and delay of GC can be reduced. Additionally, object pooling can be used to reuse objects that are no longer used so that the memory is not released immediately.

3. Conclusion

Optimizing golang gc performance is a complex process, but it is very necessary to understand its mechanism and use some techniques. When developing high-quality Go applications, we need to consider all issues caused by GC to ensure that the program can achieve optimal performance.

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