我碰到下面的代码从Writing Large, Responsive .NET Framework Apps。StringBuilder with Caching,ThreadStatic
下面的代码使用StringBuilder
创建了一个字符串,如SomeType<T1, T2, T3>
,并演示缓存StringBuilder
以提高性能。
public void Test3()
{
Console.WriteLine(GenerateFullTypeName("SomeType", 3));
}
// Constructs a name like "SomeType<T1, T2, T3>"
public string GenerateFullTypeName(string name, int arity)
{
//StringBuilder sb = new StringBuilder();
StringBuilder sb = AcquireBuilder();
sb.Append(name);
if (arity != 0)
{
sb.Append("<");
for (int i = 1; i < arity; i++)
{
sb.Append("T"); sb.Append(i.ToString()); sb.Append(", ");
}
sb.Append("T"); sb.Append(arity.ToString()); sb.Append(">");
}
//return sb.ToString();
/* Use sb as before */
return GetStringAndReleaseBuilder(sb);
}
[ThreadStatic]
private static StringBuilder cachedStringBuilder;
private static StringBuilder AcquireBuilder()
{
StringBuilder result = cachedStringBuilder;
if (result == null)
{
return new StringBuilder();
}
result.Clear();
cachedStringBuilder = null;
return result;
}
private static string GetStringAndReleaseBuilder(StringBuilder sb)
{
string result = sb.ToString();
cachedStringBuilder = sb;
return result;
}
但是,下面的两个修改方法在缓存StringBuilder方面更好吗?只有AcquireBuilder需要知道如何缓存它。
private static StringBuilder AcquireBuilder()
{
StringBuilder result = cachedStringBuilder;
if (result == null)
{
//unlike the method above, assign it to the cache
cachedStringBuilder = result = new StringBuilder();
return result;
}
result.Clear();
//no need to null it
// cachedStringBuilder = null;
return result;
}
private static string GetStringAndReleaseBuilder(StringBuilder sb)
{
string result = sb.ToString();
//other method does not to assign it again.
//cachedStringBuilder = sb;
return result;
}
另一个问题是原始方法不是线程安全的,为什么ThreadStatic在演示中使用?
下面是'AcquireBuilder'的更好实现:['ObjectPool .Get'](https://docs.microsoft.com/aspnet/core/api/microsoft.extensions.objectpool.objectpool-1) 。这是ASP.NET自己使用的;我不确定为什么作者觉得有必要提出一些原创的东西。 –
这已经[内置于框架](https://stackoverflow.com/questions/20029868/understanding-of-net-internal-stringbuildercache-class-configuration)。看起来很相似。请确保您需要它,请记住,没有过期策略的缓存是内存泄漏。 –