Re: [ptp-dev] IRemoteProcess.isCompleted occaisionally fails to report p

[Greg Watson <g.watson@xxxxxxxxxxxx>]

Dave,

Is there anything still running on the remote end? e.g. is there a shell process? You could try killing it to see if that terminates the session.

Another thought. Do you know if the remote process is using a PTY or not?

You might ultimately need to do something hackish, like adding 'echo FOO' to the command and checking to see when FOO comes back.

Greg

On Jan 24, 2018, at 7:24 AM, David Wootton <dwootton@xxxxxxxxxx> wrote:

Greg
I suspended each thread in the Eclipse debugger once I had a hung run configuration dialog

Both my reader threads are waiting
<17443150.gif>
I expected these threads had exited at this point since the remote process was gone and the associated write-side file descriptors should have been closed, causing the pending read to end, at least on Linux. I'm running Eclipse on windows, so maybe file descriptor behavior there is different.

The thread that looks like it might be a connection thread seems to be looping in PipedImputStream.awaitSpace, since I can single step thru it. There is a wait there, with a 1 second timeout.
<17931618.gif>
The Session class is com.jcraft.jsch.Session

I suspended a few other threads and did not see anything that looked like Jsch. I avoided classes that had labels/names that looked like internal Eclipse threads or other unrelated plugins.

Dave



<graycol.gif>Greg Watson ---01/23/2018 10:57:10 PM---Hi Dave, Off the top of my head I don't know, but Jsch is a nasty piece of work. Can you see if it's

From:  Greg Watson <g.watson@xxxxxxxxxxxx>
To:  Parallel Tools Platform general developers <ptp-dev@xxxxxxxxxxx>
Date:  01/23/2018 10:57 PM
Subject:  Re: [ptp-dev] IRemoteProcess.isCompleted occaisionally fails to report process completion
Sent by:  ptp-dev-bounces@xxxxxxxxxxx

---

Hi Dave,

Off the top of my head I don't know, but Jsch is a nasty piece of work. Can you see if it's stuck in the Jsch code somewhere?

Regards,
Greg

On Jan 23, 2018, at 3:00 PM, David Wootton <dwootton@xxxxxxxxxx> wrote:


I'm fixing the hangs using the LSF target configuration and have it mostly fixed. One problem I'm running into is that occasionally, the remote process (bqueues -w) exits but the IRemoteProcess.isCompleted() method still returns false, and as a result, my code loops forever waiting for process completion and the run configuation dialog is locked. I can clear the locked state by clicking the red cancel button at the bottom of the dialog.

The loop I have to wait for process completion is

for (;;) {
if (process.isCompleted()) {
break;
}
if (monitor.isCanceled()) {
process.destroy();
return new Status(IStatus.CANCEL, Activator.PLUGIN_ID, CANCELED, Messages.CommandCancelMessage, null);
}
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// Do nothing, sleep just ends early 
}
}

I see comments in the IRemoteProcess source that warn that isCompleted() and waitFor() may not work correctly if the calling thread does not read the stderr or stdout streams and the JSch process implementation is used (which appears to be my case since I see that the process builder os a JSchProcessBuilder) . However, in my case I have reads pending on both the stderr and stdout streams for at least one byte, but I am issuing those reads on a different threads from where the remote process was created. (I'm reading on separate threads to avoid my code blocking if the remote process writes so much data to either stream that the stream buffers fill and the process blocks until something reads from these streams to empty the buffer , and that fixes most of the hangs) 

I'm not sure what's going on here to cause the hang. I'm wondering if my InputStream objects need a synchronized attribute because it's being used on a different thread, but that also makes no sense since my InputStream veriable is not visible to anythig other than my code reading the stream.

Any thoughts or suggestions about what might be going on?

Thanks

Dave


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