feat: free-threaded pybind11

Signed-off-by: Henry Schreiner <[email protected]>

projects/hello-free-threading/CMakeLists.txt

@@ -13,4 +13,7 @@ find_package(
 
 python_add_library(_core MODULE src/freecomputepi/_core.cpp WITH_SOABI)
 
-install(TARGETS _core DESTINATION freecomputepi)
+find_package(pybind11 REQUIRED)
+pybind11_add_module(_pybcore MODULE src/freecomputepi/_pybcore.cpp)
+
+install(TARGETS _core _pybcore DESTINATION freecomputepi)

projects/hello-free-threading/pyproject.toml

@@ -1,5 +1,5 @@
 [build-system]
-requires = ["scikit-build-core >=0.9.5"]
+requires = ["scikit-build-core >=0.9.5", "pybind11 >=2.13.1"]
 build-backend = "scikit_build_core.build"
 
 [project]

projects/hello-free-threading/src/freecomputepi/_pybcore.cpp

@@ -0,0 +1,25 @@
+#include <pybind11/pybind11.h>
+#include <random>
+
+namespace py = pybind11;
+
+double pi(int n) {
+    double sum = 0.0;
+
+    std::random_device r;
+    std::default_random_engine e1(r());
+    std::uniform_real_distribution<double> uniform_dist(-1, 1);
+
+    for (int i = 0; i < n; i++) {
+        double x = uniform_dist(e1);
+        double y = uniform_dist(e1);
+        if (x * x + y * y <= 1.0) {
+            sum += 1.0;
+        }
+    }
+    return 4.0 * sum / n;
+}
+
+PYBIND11_MODULE(_pybcore, m, py::mod_gil_not_used()) {
+    m.def("pi", &pi);
+}

projects/hello-free-threading/src/freecomputepi/pybind.py

@@ -0,0 +1,30 @@
+import argparse
+import statistics
+import time
+from concurrent.futures import ThreadPoolExecutor
+
+from ._pybcore import pi
+
+
+def pi_in_threads(threads: int, trials: int) -> float:
+    if threads == 0:
+        return pi(trials)
+    with ThreadPoolExecutor(max_workers=threads) as executor:
+        return statistics.mean(executor.map(pi, [trials // threads] * threads))
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--threads", type=int, default=0)
+    parser.add_argument("--trials", type=int, default=100_000_000)
+    args = parser.parse_args()
+
+    start = time.monotonic()
+    π = pi_in_threads(args.threads, args.trials)
+    stop = time.monotonic()
+
+    print(f"{args.trials} trials, {π = }, {stop - start:.4} s")
+
+
+if __name__ == "__main__":
+    main()

projects/hello-free-threading/tests/test_thread.py

@@ -1,5 +1,6 @@
 import freecomputepi.comp
 import freecomputepi.pure
+import freecomputepi.pybind
 import pytest
 
 
@@ -13,3 +14,9 @@ def test_pure(threads):
 def test_comp(threads):
     π = freecomputepi.comp.pi_in_threads(threads, 100_000_000)
     assert π == pytest.approx(3.1415926535, rel=0.01)
+
+
+@pytest.mark.parametrize("threads", [0, 1, 2, 4])
+def test_pybind(threads):
+    π = freecomputepi.pybind.pi_in_threads(threads, 100_000_000)
+    assert π == pytest.approx(3.1415926535, rel=0.01)