Package com.sun.enterprise.universal.process

Class ProcessStreamDrainer

java.lang.Object
com.sun.enterprise.universal.process.ProcessStreamDrainer
public class ProcessStreamDrainer extends Object
If you don't drain a process' stdout and stderr it will cause a deadlock after a few hundred bytes of output. At that point the Process is blocked because its stdout and/or stderr buffer is full and it is waiting for the Java caller to drain it. Meanwhile the Java program is blocked waiting on the external process. This class makes this common, but messy and tricky, procedure easier. It creates 2 threads that drain output on stdout and stderr of the external process.

Sample Code: 

 ProcessBuilder pb = new ProcessBuilder("ls",  "-R", "c:/as");
 try
 {
      Process p = pb.start();
      ProcessStreamDrainer psd = ProcessStreamDrainer.drain("MyProcess", p);
      // or
      ProcessStreamDrainer psd = ProcessStreamDrainer.redirect("MyProcess", p);
      psd.waitFor(); // this is optional.
 }
 catch (Exception ex)
 {
      ex.printStackTrace();
 }
Author:
bnevins

  • Method Details

    • drain

      public static ProcessStreamDrainer drain(String processName, Process process)
      Create an instance and drain the process' stderr and stdout
      Parameters:
      process - The Process to drain
      processName - The name will be used to name the drainer threads

    • save

      public static ProcessStreamDrainer save(String processName, Process process)
      Create an instance and drain the process' stderr and stdout and save it to strings.
      Parameters:
      process - The Process to drain
      processName - The name will be used to name the drainer threads

    • redirect

      public static ProcessStreamDrainer redirect(String processName, Process process)
      Create an instance, drain and redirect the process' stderr and stdout to System.err and System.out respectively.
      Parameters:
      process - The Process to drain
      processName - The name will be used to name the drainer threads

    • dispose

      public static ProcessStreamDrainer dispose(String processName, Process process)
      Create an instance, drain and throw away the process' stderr and stdout output.
      Parameters:
      process - The Process to drain
      processName - The name will be used to name the drainer threads

    • waitFor

      public final void waitFor() throws InterruptedException
      Wait for the drain threads to die. This is guaranteed to occur after the external process dies. Note that this may, of course, block indefinitely.
      Throws:
      InterruptedException

    • getOutString

      public final String getOutString()

    • getErrString

      public final String getErrString()

    • getOutErrString

      public final String getOutErrString()