repro.py

import threading
from _io import _IOBase

def create_gc():
    io = _IOBase()
    print io
    del io
    t = threading.Timer(0.001, create_gc)
    t.start()

def call_close():
    io = _IOBase()
    print io
    io.close()
    t = threading.Timer(0.001, call_close)
    t.start()

for i in range(30):
    t1 = threading.Timer(1.0, create_gc)
    t1.start()
    t2 = threading.Timer(1.0, call_close)
    t2.start()

Demonstrates a deadlock bug in jython. First apply this patch:

diff --git a/src/org/python/modules/_io/PyIOBase.java b/src/org/python/modules/_io/PyIOBase.java
index 09f052d..7e1550c 100644
--- a/src/org/python/modules/_io/PyIOBase.java
+++ b/src/org/python/modules/_io/PyIOBase.java
@@ -733,6 +733,7 @@ public class PyIOBase extends PyObject implements FinalizableBuiltin, Traversepr

     @Override
     public void __del_builtin__() {
+        System.out.println("Deleting io object.");
         closer.dismiss();
         invoke("close");
     }

Then run the above script:

java -cp dist/jython-standalone.jar org.python.util.jython repro.py

You will see the script stop outputting and enter a deadlocked state before very long.