Runtime.exec() fails sometime to execute a command

Question

Hello,
I have a program thats using Runtime.exec to execute some external programs sequence with some redirection operators.
For e.g, I have some command as follows;
1 - C:\bin\IBRSD.exe IBRSD -s
2 - C:\bin\mcstat -n @punduk444:5000#mc -l c:\ | grep -i running | grep -v grep |wc -l
3 - ping punduk444 | grep "100%" | wc -l
...etc.
These command in sequence for a single run. The test program makes multiple such runs. So my problem is sometimes the runtime.exec() fails to execute some of the commands above (typically the 2nd one). The waitFor() returns error code (-1). That is if I loop these commands for say 30 runs then in some 1~4 runs the 2nd command fails to execute and return -1 error code.
Can some one help me out to as why this is happening? Any help is appreciated
Thanks,
~jaideep
Herer is the code snippet;
Runtime runtime = Runtime.getRuntime();
//create process object to handle result
Process process = null;
commandToRun = "cmd /c " + command;
process = runtime.exec( commandToRun );
CommandOutputReader cmdError = new CommandOutputReader(process.getErrorStream());
CommandOutputReader cmdOutput = new CommandOutputReader(process.getInputStream());
cmdError.start();
cmdOutput.start();
CheckProcess chkProcess = new CheckProcess(process);
chkProcess.start();
int retValue = process.waitFor();
if(retValue != 0)
return -1;
output = cmdOutput.getOutputData();
cmdError = null;
cmdOutput = null;
chkProcess = null;
/*******************************supporting CommandOutputReader class *********************************/
public class CommandOutputReader extends Thread
private transient InputStream inputStream; //to get output of any command
private transient String output; //output will store command output
protected boolean isDone;
public CommandOutputReader()
super();
output = "";
this.inputStream = null;
public CommandOutputReader(InputStream stream)
super();
output = "";
this.inputStream = stream;
public void setStream(InputStream stream)
this.inputStream = stream;
public String getOutputData()
return output;
public void run()
if(inputStream != null)
final BufferedReader bufferReader = new BufferedReader(new InputStreamReader(inputStream), 1024 * 128);
String line = null;
try
while ( (line = bufferReader.readLine()) != null)
if (ResourceString.getLocale() != null)
Utility.log(Level.DEBUG,line);
//output += line + System.getProperty(Constants.ALL_NEWLINE_GETPROPERTY_PARAM);
output += line + "\r\n";
System.out.println("<< "+ this.getId() + " >>" + output );
System.out.println("<< "+ this.getId() + " >>" + "closed the i/p stream...");
inputStream.close();
bufferReader.close();
catch (IOException objIOException)
if (ResourceString.getLocale() != null)
Utility.log(Level.ERROR, ResourceString.getString("io_exeception_reading_cmd_output")+
objIOException.getMessage());
output = ResourceString.getString("io_exeception_reading_cmd_output");
else
output = "io exeception reading cmd output";
finally {
isDone = true;
public boolean isDone() {
return isDone;
/*******************************supporting CommandOutputReader class *********************************/
/*******************************supporting process controller class *********************************/
public class CheckProcess extends Thread
private transient Process monitoredProcess;
private transient boolean continueLoop ;
private transient long maxWait = Constants.WAIT_PERIOD;
public CheckProcess(Process monitoredProcess)
super();
this.monitoredProcess = monitoredProcess;
continueLoop =true;
public void setMaxWait(final long max)
this.maxWait = max;
public void stopProcess()
continueLoop=false;
public void run()
//long start1 = java.util.Calendar.getInstance().getTimeInMillis();
final long start1 = System.currentTimeMillis();
while (true && continueLoop)
// after maxWait millis, stops monitoredProcess and return
if (System.currentTimeMillis() - start1 > maxWait)
if(monitoredProcess != null)
monitoredProcess.destroy();
//available for garbage collection
// @PMD:REVIEWED:NullAssignment: by jbarde on 9/28/06 7:29 PM
monitoredProcess = null;
return;
try
sleep(1000);
catch (InterruptedException e)
if (ResourceString.getLocale() != null)
Utility.log(Level.ERROR, ResourceString.getString("exception_in_sleep") + e.getLocalizedMessage());
System.out.println(ResourceString.getString("exception_in_sleep") + e.getLocalizedMessage());
else
System.out.println("Exception in sleep" + e.getLocalizedMessage());
if(monitoredProcess != null)
monitoredProcess.destroy();
//available for garbage collection
// @PMD:REVIEWED:NullAssignment: by jbarde on 9/28/06 7:29 PM
monitoredProcess = null;
/*******************************supporting process controller class *********************************/

Answer 1

Hi,
Infact the command passed to the exec() is in the form of a batch file, which contains on of these commands. I can not put all commands in one batch file due to inherent nature of the program.
But my main concern was that, why would it behave like this. If I run the same command for 30 times 1~3 times the same command can not be executed (returns with error code 1, on wiun2k pro) and rest times it works perfectly fine.
Do you see any abnormality in the code.
I ahve used the same sequence of code as in the article suggested by
"masijade". i.e having threads to monitor the process and other threads to read and empty out the input and error streams so that the buffer does not get full.
But I see here the problem is not of process getting hanged, I sense this because my waitFor() returns with error code as 1, had the process hanged it would not have returned , am I making sense?
Regards,
~jaideep