1 files changed, 26 insertions, 0 deletions
diff --git a/Lib/test/test_threading_local.py b/Lib/test/test_threading_local.py
index e48dc59..977a38a 100644
--- a/Lib/test/test_threading_local.py
+++ b/Lib/test/test_threading_local.py
@@ -42,6 +42,32 @@ class ThreadingLocalTest(unittest.TestCase):
         deadlist = [weak for weak in weaklist if weak() is None]
         self.assert_(len(deadlist) in (n-1, n), (n, len(deadlist)))
 
+    def test_derived(self):
+        # Issue 3088: if there is a threads switch inside the __init__
+        # of a threading.local derived class, the per-thread dictionary
+        # is created but not correctly set on the object.
+        # The first member set may be bogus.
+        import time
+        class Local(threading.local):
+            def __init__(self):
+                time.sleep(0.01)
+        local = Local()
+
+        def f(i):
+            local.x = i
+            # Simply check that the variable is correctly set
+            self.assertEqual(local.x, i)
+
+        threads= []
+        for i in range(10):
+            t = threading.Thread(target=f, args=(i,))
+            t.start()
+            threads.append(t)
+
+        for t in threads:
+            t.join()
+
+
 def test_main():
     suite = unittest.TestSuite()
     suite.addTest(DocTestSuite('_threading_local'))