| Re: [ptp-dev] IRemoteProcess.isCompleted occaisionally fails to report process completion |
Greg
That doesn't work. The result is that the name of the remote command is the complete string 'bqueues -l; echo EOF:$?'
I thought I could make this work by running a wrapper script, for instance /home/dwootton/hack on the remote node, where the script is
#!/bin/sh
echo "Execute: " $*
$*
echo "EOF:$?"
And then changing the invocation command in my Eclipse code to 'private static final String bqueuesCommand[] = {"/home/dwootton/hack", "bqueues", "-l"};'
The idea is that the hack script just executes exactly what it is passed.
This works correctly most of the time. However, when the bqueues command disappears, I still get absolutely no output to stdout, not even the text from my hack script.
It looks like something is just completely losing track of the remote command request.in this case.
Dave
Greg Watson ---01/26/2018 11:39:03 AM---What happens if you try a single quoted argument, e.g 'bqueues -l; echo EOF:$?' Greg
From: Greg Watson <g.watson@xxxxxxxxxxxx>
To: Parallel Tools Platform general developers <ptp-dev@xxxxxxxxxxx>
Date: 01/26/2018 11:39 AM
Subject: Re: [ptp-dev] IRemoteProcess.isCompleted occaisionally fails to report process completion
Sent by: ptp-dev-bounces@xxxxxxxxxxx
Greg
I tried adding an echo command to the bqueues command and I am not having any success. My original bqueues command that I was passing to the IRemoteProcessBuilder was a String array {"bqueues", "-l"}.
I changed that to {"bqueues", "-l", ";", "echo", "\"EOF:$?\""} and that failed with a LSF error message that there was no such queue as ";", where the semicolon is being passed as a command parameter to the bqueues command instead of as a command separator for bash.
I tried changing ';' tp "\\;" to escape the semicolon and it was still passed as a bqueues command parameter, this time '\;'.
I was able to get the pid of the bash process started to run the bqueues command one time with my original bqueues command hanging and it looks like the command being passed across is actually /bin/bash -l -c cd /autofs/home/dwootton && bqueues -l where "cd /autofs/home/dwootton && bqueues -l" is probably a string parameter to the bash -c option (which tells bash to use the string as the bash command")
So I'm not sure how I can get this hack to work. I think I have a way to deal with the return status in my Java code, but I'm stuck at getting a working command to pass across to the remote system.
Dave
<graycol.gif>Greg Watson ---01/24/2018 12:10:09 PM---Dave, Is there anything still running on the remote end? e.g. is there a shell process? You could tr
From: Greg Watson <g.watson@xxxxxxxxxxxx>
To: Parallel Tools Platform general developers <ptp-dev@xxxxxxxxxxx>
Date: 01/24/2018 12:10 PM
Subject: Re: [ptp-dev] IRemoteProcess.isCompleted occaisionally fails to report process completion
Sent by: ptp-dev-bounces@xxxxxxxxxxx
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
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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