[SOLVED] Correct way to handle standard error and output from a program when spawned via Process class from C#?

Correct way to handle standard error and output from a program when spawned via Process class from C#?

I read the documentation for Process.StandardOutput, which has this quote:

A deadlock condition can result if the parent process calls p.WaitForExit before p.StandardOutput.ReadToEnd and the child process writes enough text to fill the redirected stream.

So I'm wondering. What is the correct way to do this if I'm also afraid that StandardError could be filled in some scenarios?

Do I have to use a loop to alternate reading from standard output and error, to avoid either filling up, or is this simple code enough:

string error = proc.StandardError.ReadToEnd();
string output = proc.StandardOutput.ReadToEnd();
bool didFinish = proc.WaitForExit(60000);

Edited after some answers have been posted

So this is the right approach?

var output = new StringBuilder();
proc.OutputDataReceived += (s, e) => output.Append(e.Data);
proc.BeginOutputReadLine();
string error = proc.StandardError.ReadToEnd();
bool didFinish = proc.WaitForExit(60000);

And then I use the stringbuilder content only if the process actually finished.

Is that the right approach then?

Solution

Your example code could cause a deadlock situtation where there was something written to the StandardOutput and not to StandardError. The very next example from the documentation you linked states as much.

Essentially, what I would recommend, is using the async reads on both streams to fill a buffer as the Streams are written to, and then call WaitForExit.