Add free-threading test for mkl_random

Author: vlad-perevezentsev

mkl_random/tests/test_freethreading.py

@@ -0,0 +1,129 @@
+# Copyright (c) 2026, Intel Corporation
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+#     * Redistributions of source code must retain the above copyright notice,
+#       this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above copyright
+#       notice, this list of conditions and the following disclaimer in the
+#       documentation and/or other materials provided with the distribution.
+#     * Neither the name of Intel Corporation nor the names of its contributors
+#       may be used to endorse or promote products derived from this software
+#       without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+import os
+import sys
+import sysconfig
+import threading
+
+import numpy as np
+import pytest
+
+# Oversubscription: MKL spawns its own thread pool per calling thread, so
+# generating from many Python threads concurrently can spawn far more OS
+# threads than cores. Cap it before mkl_random/MKL initialize.
+os.environ.setdefault("MKL_NUM_THREADS", "1")
+
+import mkl_random  # noqa: E402
+
+FREE_THREADED = bool(sysconfig.get_config_var("Py_GIL_DISABLED"))
+
+
+def test_concurrent_sampling_per_instance():
+    # Each thread owns a private MKLRandomState seeded identically, so the
+    # per-instance lock + `nogil` sampling must reproduce the single-threaded
+    # result exactly regardless of concurrency.
+    n_threads = 4
+    size = 10**5 + 1  # large enough that per-thread nogil sampling overlaps
+    seed = 1234
+
+    expected = mkl_random.MKLRandomState(seed).normal(size=size)
+
+    results = [None] * n_threads
+    errors = []
+
+    def worker(i):
+        try:
+            rs = mkl_random.MKLRandomState(seed)
+            results[i] = rs.normal(size=size)
+        except Exception as exc:  # pylint: disable=broad-except
+            errors.append(exc)
+
+    threads = [
+        threading.Thread(target=worker, args=(i,)) for i in range(n_threads)
+    ]
+    for t in threads:
+        t.start()
+    for t in threads:
+        t.join()
+
+    assert not errors
+
+    for i in range(n_threads):
+        np.testing.assert_array_equal(results[i], expected)
+
+
+def test_concurrent_shared_singleton():
+    # Module-level functions share a single lock-guarded RandomState. Hammering
+    # it from many threads must not corrupt state, crash, or return garbage.
+    n_threads = 8
+    size = 10**5 + 1
+    results = [None] * n_threads
+    errors = []
+
+    def worker(i):
+        try:
+            results[i] = mkl_random.uniform(size=size)
+        except Exception as exc:  # pylint: disable=broad-except
+            errors.append(exc)
+
+    threads = [
+        threading.Thread(target=worker, args=(i,)) for i in range(n_threads)
+    ]
+    for t in threads:
+        t.start()
+    for t in threads:
+        t.join()
+
+    assert not errors
+
+    for i in range(n_threads):
+        assert results[i].shape == (size,)
+        assert np.all(np.isfinite(results[i]))
+
+
+def test_concurrent_patch_restore():
+    n_threads = 8
+    n_iters = 20
+
+    def worker():
+        for _ in range(n_iters):
+            mkl_random.patch_numpy_random()
+            mkl_random.restore_numpy_random()
+
+    threads = [threading.Thread(target=worker) for _ in range(n_threads)]
+    for t in threads:
+        t.start()
+    for t in threads:
+        t.join()
+
+    assert not mkl_random.is_patched()
+
+
+@pytest.mark.skipif(
+    not FREE_THREADED, reason="requires a free-threaded CPython build"
+)
+def test_gil_not_reenabled_on_import():
+    assert not sys._is_gil_enabled()  # pylint: disable=no-member