.net通用垃圾收集优化技术

金士顿2023-11-01 22:26

Avoid unnecessary allocations in hot paths

For example, in a tight loop or frequently called method, try to avoid creating new objects.

Bad:

csharp 复制代码

for(int i = 0; i < 100; i++) {
  var obj = new MyObject();
  //...
}

Good:

csharp 复制代码

MyObject obj = null;
for(int i = 0; i < 100; i++) {
  if(obj == null) {
    obj = new MyObject(); 
  }
  // Reuse obj instead of reallocating
}

Reuse buffers instead of allocating new ones

Avoid unnecessary allocations in hot paths

Reuse buffers instead of allocating new ones

For byte arrays or other buffers, allocate once and reuse instead of reallocating.

Bad:

csharp 复制代码

byte[] buffer = new byte[1024];

void ProcessData() {
  buffer = new byte[data.Length]; // re-allocate each time
  //...
}

Good:

csharp 复制代码

byte[] buffer = new byte[1024];

void ProcessData() {
  if(buffer.Length < data.Length) {
    // Resize only if needed
    buffer = new byte[data.Length]; 
  }

  // Reuse buffer
  //...
}

Use structs instead of classes where possible

Use structs instead of classes where possible

Structs can avoid heap allocations.

Bad:

csharp 复制代码

class Data {
  public int x;
  public int y;
}

Data data = new Data(); // allocated on heap

Good:

csharp 复制代码

struct Data {
   public int x;
   public int y; 
}

Data data; // allocated on stack

Here are some examples to illustrate those general garbage collection optimization techniques: