c# – 罗斯林启动时间慢

我注意到Roslyn解析/编译的启动时间是一个相当重要的一次性成本.编辑：我正在使用Roslyn CTP MSI(程序集在GAC中).这是预期的吗？有没有解决方法？

运行下面的代码与1次迭代(约3秒)和300次迭代(约3秒)的时间几乎相同.

[Test]
public void Test()
{
    var iters = 300;
    foreach (var i in Enumerable.Range(0,iters))
    {
        // Parse the source file using Roslyn
        SyntaxTree SyntaxTree = SyntaxTree.ParseText(@"public class Foo" + i + @" { public void Exec() { } }");

        // Add all the references we need for the compilation
        var references = new List<MetadataReference>();
        references.Add(new MetadataFileReference(typeof(int).Assembly.Location));

        var compilationOptions = new CompilationOptions(outputKind: OutputKind.DynamicallyLinkedLibrary);

        // Note: using a fixed assembly name,which doesn't matter as long as we don't expect cross references of generated assemblies
        var compilation = Compilation.Create("SomeAssemblyName",compilationOptions,new[] {SyntaxTree},references);

        // Generate the assembly into a memory stream
        var memStream = new MemoryStream();

        // if we comment out from this line and down,the runtime drops to ~.5 seconds
        EmitResult emitResult = compilation.Emit(memStream);

        var asm = Assembly.Load(memStream.GetBuffer());
        var type = asm.GetTypes().Single(t => t.Name == "Foo" + i);
    }
}

解决方法

我认为一个问题是使用内存流,而应该尝试使用动态模块和ModuleBuilder.总体而言,代码执行速度更快,但仍然有较重的首次加载方案.我自己对罗斯林很陌生,所以我不确定为什么这会更快,但这里是改变的代码.

var iters = 300;
        foreach (var i in Enumerable.Range(0,iters))
        {
            // Parse the source file using Roslyn
            SyntaxTree SyntaxTree = SyntaxTree.ParseText(@"public class Foo" + i + @" { public void Exec() { } }");

            // Add all the references we need for the compilation
            var references = new List<MetadataReference>();
            references.Add(new MetadataFileReference(typeof(int).Assembly.Location));

            var compilationOptions = new CompilationOptions(outputKind: OutputKind.DynamicallyLinkedLibrary);

            // Note: using a fixed assembly name,which doesn't matter as long as we don't expect cross references of generated assemblies
            var compilation = Compilation.Create("SomeAssemblyName",new[] { SyntaxTree },references);

            var assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(new System.Reflection.AssemblyName("CustomerA"),System.Reflection.Emit.AssemblyBuilderAccess.RunAndCollect);

            var moduleBuilder = assemblyBuilder.DefineDynamicModule("MyModule");

            System.Diagnostics.Stopwatch watch = new System.Diagnostics.Stopwatch();
            watch.Start();

            // if we comment out from this line and down,the runtime drops to ~.5 seconds
            var emitResult = compilation.Emit(moduleBuilder);

            watch.Stop();

            System.Diagnostics.Debug.WriteLine(watch.ElapsedMilliseconds);

            if (emitResult.Diagnostics.LongCount() == 0)
            {
                var type = moduleBuilder.GetTypes().Single(t => t.Name == "Foo" + i);

                System.Diagnostics.Debug.Write(type != null);
            }
        }

通过使用这种技术,编译只需96毫秒,在后续迭代中需要大约3到15毫秒.所以我认为你可能在第一个负载场景方面增加一些开销.

对不起,我无法解释为什么它更快！我自己就是在研究Roslyn,今晚晚些时候会做更多的挖掘,看看我是否能找到更多关于ModuleBuilder在内存流上提供的证据.

c# – 罗斯林启动时间慢

解决方法

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