我有以下代码:
info = new System.Diagnostics.ProcessStartInfo("TheProgram.exe", String.Join(" ", args));
info.CreateNoWindow = true;
info.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
info.RedirectStandardOutput = true;
info.UseShellExecute = false;
System.Diagnostics.Process p = System.Diagnostics.Process.Start(info);
p.WaitForExit();
Console.WriteLine(p.StandardOutput.ReadToEnd()); //need the StandardOutput contents
我知道我正在启动的进程的输出大约有7MB长。在Windows控制台中运行它可以正常工作。不幸的是，从编程的角度来看，它会无限期地挂在WaitForExit上。还要注意，对于较小的输出(比如3KB)，这段代码不会挂起。
ProcessStartInfo中的内部StandardOutput是否可能不能缓冲7MB?如果是，我该怎么办?如果不是，我做错了什么?
我试图通过考虑Mark Byers, Rob, stevejay的回答，创建一个类来解决你使用异步流读取的问题。这样做，我意识到有一个与异步流程输出流读取相关的错误。
我在微软报告了这个漏洞:https://connect.microsoft.com/VisualStudio/feedback/details/3119134
简介:
You can't do that:
process.BeginOutputReadLine(); process.Start();
You will receive System.InvalidOperationException : StandardOut has
not been redirected or the process hasn't started yet.
============================================================================================================================
Then you have to start asynchronous output read after the process is
started:
process.Start(); process.BeginOutputReadLine();
Doing so, make a race condition because the output stream can receive
data before you set it to asynchronous:
process.Start();
// Here the operating system could give the cpu to another thread.
// For example, the newly created thread (Process) and it could start writing to the output
// immediately before next line would execute.
// That create a race condition.
process.BeginOutputReadLine();
============================================================================================================================
Then some people could say that you just have to read the stream
before you set it to asynchronous. But the same problem occurs. There
will be a race condition between the synchronous read and set the
stream into asynchronous mode.
============================================================================================================================
There is no way to acheive safe asynchronous read of an output stream
of a process in the actual way "Process" and "ProcessStartInfo" has
been designed.
对于您的情况，您最好使用其他用户建议的异步读取。但是您应该意识到，由于竞态条件，您可能会错过一些信息。
简介
目前接受的答案不工作(抛出异常)，有太多的变通方法，但没有完整的代码。这显然是在浪费很多人的时间，因为这是一个很受欢迎的问题。
结合Mark Byers的回答和Karol Tyl的回答，我根据我想如何使用流程编写了完整的代码。Start方法。
使用
我用它来创建git命令的进度对话框。我是这样使用它的:
private bool Run(string fullCommand)
{
Error = "";
int timeout = 5000;
var result = ProcessNoBS.Start(
filename: @"C:\Program Files\Git\cmd\git.exe",
arguments: fullCommand,
timeoutInMs: timeout,
workingDir: @"C:\test");
if (result.hasTimedOut)
{
Error = String.Format("Timeout ({0} sec)", timeout/1000);
return false;
}
if (result.ExitCode != 0)
{
Error = (String.IsNullOrWhiteSpace(result.stderr))
? result.stdout : result.stderr;
return false;
}
return true;
}
理论上，您还可以结合stdout和stderr，但我还没有对此进行测试。
Code
public struct ProcessResult
{
public string stdout;
public string stderr;
public bool hasTimedOut;
private int? exitCode;
public ProcessResult(bool hasTimedOut = true)
{
this.hasTimedOut = hasTimedOut;
stdout = null;
stderr = null;
exitCode = null;
}
public int ExitCode
{
get
{
if (hasTimedOut)
throw new InvalidOperationException(
"There was no exit code - process has timed out.");
return (int)exitCode;
}
set
{
exitCode = value;
}
}
}
public class ProcessNoBS
{
public static ProcessResult Start(string filename, string arguments,
string workingDir = null, int timeoutInMs = 5000,
bool combineStdoutAndStderr = false)
{
using (AutoResetEvent outputWaitHandle = new AutoResetEvent(false))
using (AutoResetEvent errorWaitHandle = new AutoResetEvent(false))
{
using (var process = new Process())
{
var info = new ProcessStartInfo();
info.CreateNoWindow = true;
info.FileName = filename;
info.Arguments = arguments;
info.UseShellExecute = false;
info.RedirectStandardOutput = true;
info.RedirectStandardError = true;
if (workingDir != null)
info.WorkingDirectory = workingDir;
process.StartInfo = info;
StringBuilder stdout = new StringBuilder();
StringBuilder stderr = combineStdoutAndStderr
? stdout : new StringBuilder();
var result = new ProcessResult();
try
{
process.OutputDataReceived += (sender, e) =>
{
if (e.Data == null)
outputWaitHandle.Set();
else
stdout.AppendLine(e.Data);
};
process.ErrorDataReceived += (sender, e) =>
{
if (e.Data == null)
errorWaitHandle.Set();
else
stderr.AppendLine(e.Data);
};
process.Start();
process.BeginOutputReadLine();
process.BeginErrorReadLine();
if (process.WaitForExit(timeoutInMs))
result.ExitCode = process.ExitCode;
// else process has timed out
// but that's already default ProcessResult
result.stdout = stdout.ToString();
if (combineStdoutAndStderr)
result.stderr = null;
else
result.stderr = stderr.ToString();
return result;
}
finally
{
outputWaitHandle.WaitOne(timeoutInMs);
errorWaitHandle.WaitOne(timeoutInMs);
}
}
}
}
}
我知道这是晚餐，但是，在读完这一整页后，没有一个解决方案对我来说是有效的，尽管我没有尝试Muhammad Rehan，因为代码有点难理解，尽管我猜他是在正确的轨道上。当我说它不工作时，这并不完全正确，有时它会工作得很好，我猜这与EOF标记之前的输出长度有关。
不管怎样，对我来说有效的解决方案是使用不同的线程来读取StandardOutput和StandardError并写入消息。
StreamWriter sw = null;
var queue = new ConcurrentQueue<string>();
var flushTask = new System.Timers.Timer(50);
flushTask.Elapsed += (s, e) =>
{
while (!queue.IsEmpty)
{
string line = null;
if (queue.TryDequeue(out line))
sw.WriteLine(line);
}
sw.FlushAsync();
};
flushTask.Start();
using (var process = new Process())
{
try
{
process.StartInfo.FileName = @"...";
process.StartInfo.Arguments = $"...";
process.StartInfo.UseShellExecute = false;
process.StartInfo.RedirectStandardOutput = true;
process.StartInfo.RedirectStandardError = true;
process.Start();
var outputRead = Task.Run(() =>
{
while (!process.StandardOutput.EndOfStream)
{
queue.Enqueue(process.StandardOutput.ReadLine());
}
});
var errorRead = Task.Run(() =>
{
while (!process.StandardError.EndOfStream)
{
queue.Enqueue(process.StandardError.ReadLine());
}
});
var timeout = new TimeSpan(hours: 0, minutes: 10, seconds: 0);
if (Task.WaitAll(new[] { outputRead, errorRead }, timeout) &&
process.WaitForExit((int)timeout.TotalMilliseconds))
{
if (process.ExitCode != 0)
{
throw new Exception($"Failed run... blah blah");
}
}
else
{
throw new Exception($"process timed out after waiting {timeout}");
}
}
catch (Exception e)
{
throw new Exception($"Failed to succesfully run the process.....", e);
}
}
}
希望这能帮助那些认为这很难的人!
我也有同样的问题，但原因不同。但是在Windows 8下会发生，而在Windows 7下不会。下面这行似乎是导致这个问题的原因。
pProcess.StartInfo.UseShellExecute = False
解决方案是不禁用UseShellExecute。我现在收到一个Shell弹出窗口，这是不需要的，但比程序等待什么特别的事情发生要好得多。所以我添加了如下的解决方法:
pProcess.StartInfo.WindowStyle = ProcessWindowStyle.Hidden
现在唯一让我困扰的是为什么在Windows 8下会出现这种情况。
