Fixed database typo and removed unnecessary class identifier.

venv/Lib/site-packages/scipy/_lib/tests/test__threadsafety.py

@@ -0,0 +1,51 @@
+import threading
+import time
+import traceback
+
+from numpy.testing import assert_
+from pytest import raises as assert_raises
+
+from scipy._lib._threadsafety import ReentrancyLock, non_reentrant, ReentrancyError
+
+
+def test_parallel_threads():
+    # Check that ReentrancyLock serializes work in parallel threads.
+    #
+    # The test is not fully deterministic, and may succeed falsely if
+    # the timings go wrong.
+
+    lock = ReentrancyLock("failure")
+
+    failflag = [False]
+    exceptions_raised = []
+
+    def worker(k):
+        try:
+            with lock:
+                assert_(not failflag[0])
+                failflag[0] = True
+                time.sleep(0.1 * k)
+                assert_(failflag[0])
+                failflag[0] = False
+        except Exception:
+            exceptions_raised.append(traceback.format_exc(2))
+
+    threads = [threading.Thread(target=lambda k=k: worker(k))
+               for k in range(3)]
+    for t in threads:
+        t.start()
+    for t in threads:
+        t.join()
+
+    exceptions_raised = "\n".join(exceptions_raised)
+    assert_(not exceptions_raised, exceptions_raised)
+
+
+def test_reentering():
+    # Check that ReentrancyLock prevents re-entering from the same thread.
+
+    @non_reentrant()
+    def func(x):
+        return func(x)
+
+    assert_raises(ReentrancyError, func, 0)