C# - Process - Async - Read all output

Question

Trying to use Process class and it's async features. Couldn't figure out how to read all output from Process before the program exits. Please help!!

Here's my code,

void RunProcess()
{
  Process process = new Process
  {
      StartInfo = new ProcessStartInfo
      {
          FileName = CmdName,
          Arguments = CmdArgs,
          CreateNoWindow = true,
          WindowStyle = ProcessWindowStyle.Hidden,
          RedirectStandardOutput = true,
          RedirectStandardError = true,
          UseShellExecute = false
      }
  };

  using(process)
  {
      process.OutputDataReceived += Process_OutputDataReceived;

      process.Start();
      process.BeginOutputReadLine();

      process.WaitForExit(); // Even waiting for exit here.

      _logger.Debug("End of process");
  }
} // void RunProcess()

void Process_OutputDataReceived(object sender, DataReceivedEventArgs e)
{
  if (!String.IsNullOrEmpty(e.Data))
      _logger.Debug($"\t{e.Data}");
}

I have a other code that runs for at least another 30 - 45 secs after RunProcess() method is called and done, but don't see the output from my process anywhere in the logs.

If I run the program synchronously, I get all the output. But see no output when run async. Does anyone know what I am doing wrong, please?

(Updating question to make it more clear!)

The code I posted above works, and is minimal ( stripped out validations, classes, etc). I am looking for suggestions on how to make my program stop until full output is captured in log files. Does anyone know if there is a way to make it happen with the combination of WaitForExit and event call like I have in code above, please? It seems the process is completing first and terminating the event handler before it could print the log lines.

Many Thanks in advance!!

How is it that you started a new process synchronously? A new process is a separate process from the current one. I see that you setup a `WaitForExit` block. Is that what you are referring to when you say synch/async? — P.Brian.Mackey, Apr 30 '18 at 17:25
@P.Brian.Mackey yes. I meant async from the `Process_OutputDataReceived` event. I am under the impression that the event should print all data because of `WaitForExit`, before moving onto next line. Apparently, I am missing something; will look into `async/await` below. — scorpion35, Apr 30 '18 at 17:36

score 0 · Answer 1 · answered Apr 30 '18 at 17:14

0

You can organize your code a little better. Make some class to contain your process. Take a look at how to do async/await.

Remove the line below and read the output from the process its self instead of delegating it.

  process.OutputDataReceived += Process_OutputDataReceived;

How and When to use `async` and `await`

answered Apr 30 '18 at 17:14

Zakk Diaz

1,063
10
15

Additionally this post has information on how to use the delegate https://stackoverflow.com/questions/50105158/c-sharp-process-async-read-all-output/50105201#50105201 – Zakk Diaz Apr 30 '18 at 17:19
Thank you! I will look into `async/await` now. – scorpion35 Apr 30 '18 at 17:32

C# - Process - Async - Read all output

1 Answers1