App hangs on MacOS High Sierra

  1. ‹ Older
  2. 4 months ago

    What's strange is that in order to reproduce this hang, we have to send a particular command to the Shell that change the behavior of the shell app. Further, the command needs to be sent at a particular time. If we don't send the command, the hang does not occur. If we send it earlier or later, the hang does not occur. If we send it at the right time, the hang occurs after some number of additional commands are sent to the shell. The timer I mentioned above control the frequency at which those additional commands are sent. The faster those additional commands are sent, the faster the hang will occur. So it seems that a particular command puts the app in state where it's going to eventually hang, and then sending some number of additional commands triggers the hang. All commands are JSON strings sent via Shell.WriteLine().

  3. This looks to be an issue with our Java app that's running in the Shell. It's locking up for some time and causing the Xojo app to freeze. Not a Xojo issue unless you consider the Shell instance locking up an issue.

  4. Douglas H

    Jan 17 Pre-Release Testers

    @Thomas E Just create an empty Xcode project and attach to the running process. Now press the pause button and you can look where it hangs. It works well.

    Can you elaborate on "... and attach to the running process"?

    This sounds like a good trick to have in the bag, but I'm not entirely sure how to do what you suggest.

  5. Thomas E

    Jan 17 Pre-Release Testers

    In Xcode you can use "Attach to process…" in Debug menu. Then you can pause the process similar to Xojo and look at the current stacks in the used threads.

  6. FYI we did identify the issue with the console app that was running in the Shell instance. It was some sort of deadlock related to thread wait/notify in Java. We actually couldn't address the issue directly and ended up coding up a workaround. The app no longer locks up and the issue has gone away. It is strange, as I mentioned above, that a lock up inside the shell app would cause Xojo to hang as well.

  7. Tim P

    Jan 22 Pre-Release Testers, XDC Speakers

    @KonstantinBokarius It is strange, as I mentioned above, that a lock up inside the shell app would cause Xojo to hang as well.

    That is actually documented behavior and is to be expected of synchronous Shell instances:
    http://docs.xojo.com/index.php/Shell.Mode

    "Synchronous shells block the main UI thread, even when they are in a thread themselves. For long-running shell processes, use one of the other shell modes instead."

or Sign Up to reply!