Message8771

So this has an easy solution. We simply need to remove the ThreadLocal in PythonInterpreter#cleanup. Here's the full diff:

diff -r 4de0eff57af5 src/org/python/jsr223/PyScriptEngine.java
--- a/src/org/python/jsr223/PyScriptEngine.java	Thu Jun 19 19:38:55 2014 +0100
+++ b/src/org/python/jsr223/PyScriptEngine.java	Thu Jun 19 16:37:03 2014 -0600
@@ -17,7 +17,7 @@
 import javax.script.SimpleBindings;
 import org.python.util.PythonInterpreter;
 
-public class PyScriptEngine extends AbstractScriptEngine implements Compilable, Invocable {
+public class PyScriptEngine extends AbstractScriptEngine implements Compilable, Invocable, AutoCloseable {
 
     private final PythonInterpreter interp;
     private final ScriptEngineFactory factory;
@@ -231,4 +231,8 @@
             return PyScriptEngine.this.eval(code, ctx);
         }
     }
+
+    public void close() {
+        interp.close();
+    }
 }
diff -r 4de0eff57af5 src/org/python/util/PythonInterpreter.java
--- a/src/org/python/util/PythonInterpreter.java	Thu Jun 19 19:38:55 2014 +0100
+++ b/src/org/python/util/PythonInterpreter.java	Thu Jun 19 16:37:03 2014 -0600
@@ -25,7 +25,7 @@
  * The PythonInterpreter class is a standard wrapper for a Jython interpreter
  * for embedding in a Java application.
  */
-public class PythonInterpreter {
+public class PythonInterpreter implements AutoCloseable {
 
     // Defaults if the interpreter uses thread-local state
     protected PySystemState systemState;
@@ -352,6 +352,11 @@
         } catch (PyException pye) {
             // fall through
         }
+        threadLocals.remove();
         sys.cleanup();
     }
+
+    public void close() {
+        cleanup();
+    }
 }

I modified your test program slightly to use the try-with-resource form introduced by Java 7:

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import javax.script.ScriptException;
import org.python.jsr223.PyScriptEngine;
import org.python.jsr223.PyScriptEngineFactory;

public class exhaust {

    public static void main(String[] argv) {
	ExecutorService pool = Executors.newSingleThreadExecutor();

	int i = 0;
	while (true) {
	    i++;
	    if (i % 10 == 0) {
		System.out.println("Iteration " + i);
	    }

	    pool.submit(new Runnable() {
		    @Override
		    public void run() {
			PyScriptEngineFactory factory = new PyScriptEngineFactory();
			try (PyScriptEngine engine = (PyScriptEngine) factory.getScriptEngine()) {
			    engine.eval("s = 'hello' + ' world'");
			} catch (ScriptException e) {
			}
		    }
		});
            try {
		Thread.sleep(10);
	    } catch (InterruptedException e) {
		break;
	    }
	}
    }
}

Sorry it took so long for us to take a look!