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From "Kristian Rosenvold (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (EXEC-34) Race condition prevent watchdog working using ExecuteStreamHandler
Date Fri, 18 Nov 2011 10:00:52 GMT

     [ https://issues.apache.org/jira/browse/EXEC-34?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Kristian Rosenvold updated EXEC-34:
-----------------------------------

    Attachment: EXEC34.patch

Atatched is a patch that fixes EXEC-34. The patch enables the failing tests that were already
in the codebase.

We have just ported the selenium project to commons-exec, and I think all sorts of TESTS are
the valid use cases for this patch; for instance: A test starts a process, and wants to verify
that the process is running. That implies calling watching.isWatching as one option. We had
/lots/ of problems with this race condition when porting selenium and we worked around the
problem by subclassing the watchdog.

I will also be porting apache-maven to use commons-exec sometime soon, and I expect to be
running into the same problems with tests there.
                
> Race condition prevent watchdog working using ExecuteStreamHandler
> ------------------------------------------------------------------
>
>                 Key: EXEC-34
>                 URL: https://issues.apache.org/jira/browse/EXEC-34
>             Project: Commons Exec
>          Issue Type: Bug
>         Environment: Windows Vista 64bit, dual core CPU
>            Reporter: Marco Ferrante
>            Assignee: Siegfried Goeschl
>            Priority: Minor
>         Attachments: EXEC34.patch
>
>
> Consider this test case (in _DefaultExecutorTest_ class):
> {noformat}
>     /**
>      * Start a async process using a stream handler and terminate it manually
>      * before the watchdog timeout occurs
>      */
>     public void testExecuteAsyncWithStreamHandlerAndUserTermination() throws Exception
{
>         CommandLine cl = new CommandLine(foreverTestScript);
>         ExecuteWatchdog watchdog = new ExecuteWatchdog(Integer.MAX_VALUE);
>         PumpStreamHandler streamHanlder = new PumpStreamHandler(System.out, System.err);
>         exec.setStreamHandler(streamHanlder);
>         MockExecuteResultHandler handler = new MockExecuteResultHandler();
>         exec.execute(cl, handler);
>         // DON'T wait for script to run
>         //Thread.sleep(2000);
>         // teminate it
>         watchdog.destroyProcess();
>         assertTrue("Watchdog should have killed the process",watchdog.killedProcess());
>     }
> {noformat}
> It fails (at least in my environment) because when _watchdog.destroyProcess()_ is invoked
the external process is not bound to the watchdog yet.
> Although there are possible several workarounds, but all of them seem to me very intrusive
in the code. So, I prefer some discussion before preparing and submitting a patch.
> IMHO, the watchdog should handle a reference to the thread running the process, not to
the process itself. In this way, interrupting signals can be transport using default _interrupt()_
method of class _Thread_.

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