.net秒表的正确性(Correctness of .net stopwatch)

.net秒表的正确性(Correctness of .net stopwatch)

我们正在调试一些性能问题，并注意到秒表的一些奇怪结果。

我们有一个调用Web服务的客户端 我们使用秒表在Web服务的服务层记录时间 我们使用datetime.now.ticks记录下层的时间

第2层只是一个通过层，有2行日志记录。

记录的时间是：

110毫秒 52125毫秒 125毫秒

我们原本预计2小于1，尽管没有api精确到1 ms。

我们在每个服务电话中创建一个新的秒表，所以这不是旧秒表重新启动的时间。

有谁知道为什么我们得到这些数字？

编辑

2和3位于同一台计算机和相同的应用程序域中

秒表代码是：

var sw = new Stopwatch(); sw.Start(); //code to call layer 3 sw.Stop(); orchestrationContext.LogOperationTime(functionName, sw.ElapsedMilliseconds);

在第3层记录时间

protected DateTime StartTime { get; set; } StartTime = DateTime.Now; // code new TimeSpan(DateTime.Now.Ticks - StartTime.Ticks).Milliseconds

1的日志记录位于单独的计算机上，使用Websphere进行日志记录。

We are debugging some performace problems and have notice some strange results from stopwatch.

We have a client that calls a web service We log the time at the service layer og the web service with stop watch We log the time at the lower layer with datetime.now.ticks

Layer 2 is just a pass through layer with 2 lines of logging.

The times recorded are:

110 ms 52125 ms 125 ms

We had expected 2 to be less than 1, although no api is accurate to 1 ms.

We create a new stopwatch in each service call so this is not the time of an old stopwatch thar has been restarted.

Anyone know why we are getting these figures?

Edit

2 and 3 are on the same machine and the same app domain

The stopwatch code is:

var sw = new Stopwatch(); sw.Start(); //code to call layer 3 sw.Stop(); orchestrationContext.LogOperationTime(functionName, sw.ElapsedMilliseconds);

logging of time in layer 3

protected DateTime StartTime { get; set; } StartTime = DateTime.Now; // code new TimeSpan(DateTime.Now.Ticks - StartTime.Ticks).Milliseconds

The logging of 1 is on a seperate machine, logging using Websphere.

最满意答案

好的，你的第二个代码示例应该返回TimeSpan.TotalMilliseconds ，使用Milliseconds你将得到第二个子部分。

为什么不在第3层代码中使用StopWatch ，与第2层代码的样式相同，它更准确？

你的问题标题是“StopWatch的正确性”，但似乎你正在比较香蕉与桃子和苹果。 如果您的硬件或操作系统支持， StopWatch将使用HighResolution计时器，否则它将回HighResolution System.Timer ，它提供大约15ms的粒度。

我无法评论如何或是否使用WebSphere，但它不会提供比StopWatch更准确的时序，除非它使用API​​来处理其他一些高精度时间源。

Okay, your second code sample should be returning TimeSpan.TotalMilliseconds, using just Milliseconds you will get the sub second part.

Why aren't you using a StopWatch in the layer 3 code, in the same style as your layer 2 code, it is more accurate?

Your question title is "Correctness of StopWatch" but it seems you are comparing bananas with peaches and apples. StopWatch will use a HighResolution timer if supported by your hardware or operating system otherwise it will fallback to a System.Timer which offers a granularity of around 15ms.

I can't comment on how or whether to use WebSphere but it will not offer more accurate timing than StopWatch unless it uses an API to some other high accuracy time source.