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From "Siegfried Goeschl (JIRA)" <j...@apache.org>
Subject [jira] Updated: (EXEC-49) "Write dead end" IOException when using Piped streams w/PumpStreamHandler
Date Fri, 05 Nov 2010 16:36:55 GMT

     [ https://issues.apache.org/jira/browse/EXEC-49?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Siegfried Goeschl updated EXEC-49:
----------------------------------

    Fix Version/s:     (was: 1.1.1)
                   1.2

> "Write dead end" IOException when using Piped streams w/PumpStreamHandler
> -------------------------------------------------------------------------
>
>                 Key: EXEC-49
>                 URL: https://issues.apache.org/jira/browse/EXEC-49
>             Project: Commons Exec
>          Issue Type: Bug
>    Affects Versions: 1.1
>         Environment: RHEL 5, Ubuntu 10.04
>            Reporter: Kevin Telford
>            Assignee: Siegfried Goeschl
>            Priority: Minor
>             Fix For: 1.2
>
>   Original Estimate: 4h
>  Remaining Estimate: 4h
>
> {code:title=Sad Trombone}
> java.io.IOException: Write end dead
> 	at java.io.PipedInputStream.read(PipedInputStream.java:294)
> 	at com.mycompany.commonsexecrunner.App.main(App.java:48)
> {code}
> I came across this issue when I was trying to capture stdout with a PipedOutputStream
and then pass that to a PipedInputStream.  The following code will produce the error.  The
reason for the error is the PipedOutputStream is not being closed correctly, causing the PipedInputStream
to break.
> {code:title=Throws IOException}
>     public static void main(String[] args) {
>         System.out.println("Hello world");
>         CommandLine cl = CommandLine.parse("/bin/ls");
>         cl.addArgument("/opt");
>         DefaultExecuteResultHandler handler = new DefaultExecuteResultHandler();
>         PipedOutputStream stdout = new PipedOutputStream();
>         PumpStreamHandler psh = new PumpStreamHandler(stdout);
>         Executor exec = new DefaultExecutor();
>         exec.setStreamHandler(psh);
>         try {
>             System.out.println("Preparing to execute process - commandLine=" + cl.toString());
>             exec.execute(cl, handler);
>             System.out.println("Process spun off successfully - process=" + cl.getExecutable());
>         } catch (ExecuteException ex) {
>             ex.printStackTrace();
>         } catch (IOException ex) {
>             ex.printStackTrace();
>         }
>         
>         PipedInputStream pis = null;
>         try {
>             pis = new PipedInputStream(stdout);
>         } catch (IOException ex) {
>             ex.printStackTrace();
>         }
>         int x;
>         try {
>             while ((x = pis.read()) >= 0) {
>                 System.out.println("pis.available() " + pis.available());
>                 System.out.println("x " + x);
>             }
>         } catch  (IOException ex) {
>             ex.printStackTrace();
>         } finally {
>             try {
>                 pis.close();
>             } catch (IOException ex) {
>             }
>         }
>         System.out.println("Goodbye world");
>     }
> {code}
> I was able to mitigate the error by modifying the createProcessOutputPump() method in
the PumpStreamHandler class to accept the boolean value closeWhenExhausted, like was used
for the setProcessInputStream() method.
> {code}
> protected void createProcessOutputPump(final InputStream is, final OutputStream os, final
boolean closeWhenExhausted) {
>     outputThread = createPump(is, os, closeWhenExhausted);
> }
> {code}
> This solution isn't implemented in the best way because in the end you have to pass a
boolean value all the way down and it's kind of messy, but its a start.

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