Extension can hang if you halt

This example is stupid, but I wonder if it means there are other conditions under which the extension will hang.

I was curious if closing down and opening the extension had any memory leakage (it didn't as far as I could tell), so I ran

repeat 10000 [py:setup py:python3]

It took a long time, so I just halted it. I got the message below, and now I can't get the extension to py:setup again. Removing the extension, recompiling, adding it, and recompiling doesn't work. Running __reload_extensions also doesn't work.

NetLogo is unable to supply you with more details about this error.  Please report the problem 
 at https://github.com/NetLogo/NetLogo/issues, or to bugs@ccl.northwestern.edu, and paste the 
contents of this window into your report. 


java.lang.InterruptedException
 at java.lang.Object.wait(Native Method)
 at java.lang.UNIXProcess.waitFor(UNIXProcess.java:412)
 at org.nlogo.extensions.py.PythonSubprocess.close(PythonExtension.scala:481)
 at org.nlogo.extensions.py.PythonExtension$.$anonfun$pythonProcess_$eq$1(PythonExtension.scala:49)
 at org.nlogo.extensions.py.PythonExtension$.$anonfun$pythonProcess_$eq$1$adapted(PythonExtension.scala:49)
 at scala.Option.foreach(Option.scala:274)
 at org.nlogo.extensions.py.PythonExtension$.pythonProcess_$eq(PythonExtension.scala:49)
 at org.nlogo.extensions.py.SetupPython$.perform(PythonExtension.scala:549)
 at org.nlogo.prim._extern.perform(_extern.java:36)
 at org.nlogo.nvm.Context.stepConcurrent(Context.java:107)
 at org.nlogo.nvm.ConcurrentJob.step(ConcurrentJob.scala:65)
 at org.nlogo.job.JobThread.runPrimaryJobs(JobThread.scala:133)
 at org.nlogo.job.JobThread.$anonfun$run$1(JobThread.scala:68)
 at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
 at scala.util.control.Exception$Catch.apply(Exception.scala:228)
 at org.nlogo.api.Exceptions$.handling(Exceptions.scala:41)
 at org.nlogo.job.JobThread.run(JobThread.scala:66)

NetLogo 6.1.0
main: org.nlogo.app.AppFrame
thread: AWT-EventQueue-0
Java HotSpot(TM) 64-Bit Server VM 1.8.0_202 (Oracle Corporation; 1.8.0_202-b08)
operating system: Mac OS X 10.14.6 (x86_64 processor)
Scala version 2.12.8
JOGL: (3D View not initialized)
OpenGL Graphics: (3D View not initialized)
model: Untitled

01:12:41.017 AddJobEvent (org.nlogo.app.common.CommandLine) AWT-EventQueue-0
01:12:41.017 OutputEvent (org.nlogo.app.common.CommandLine) AWT-EventQueue-0
01:12:41.017 CompiledEvent (org.nlogo.window.CompilerManager) AWT-EventQueue-0
01:12:40.999 CompileMoreSourceEvent (org.nlogo.app.common.CommandLine) AWT-EventQueue-0
01:12:40.877 PeriodicUpdateEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) AWT-EventQueue-0
01:12:40.672 PeriodicUpdateEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) AWT-EventQueue-0
01:12:40.470 PeriodicUpdateEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) AWT-EventQueue-0
01:12:40.267 PeriodicUpdateEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) AWT-EventQueue-0
01:12:40.065 PeriodicUpdateEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) AWT-EventQueue-0
01:12:39.864 PeriodicUpdateEvent (org.nlogo.app.App$$anon$4 (org.nlogo.window.GUIWorkspace)) AWT-EventQueue-0

Start with PythonExtension.scala, especially PythonSubprocess.close and SetupPython.perform, using the reported repeat-and-halt sequence to reproduce the failure. Check that after halting, py:setup and __reload_extensions work again; the stack trace and recovery behavior should no longer show the extension stuck.