Add a test case that exercises pybind11_protobuf use in parallel.

Tests both with and without the GIL held, and it uncovered an issue in
pybind11 handling of std::string_view when the GIL is not held.

BUG: pybind/pybind11#2765

The bug is that the string_view constructs an object which should be placed on life_support, but due to the underlying mechanism it is not retained in a multi-threaded environment.

PiperOrigin-RevId: 394314149

Author: laramiel

pybind11_protobuf/tests/BUILD

@@ -208,3 +208,26 @@ py_test(
         "@com_google_absl_py//absl/testing:parameterized",
     ],
 )
+
+pybind_extension(
+    name = "thread_module",
+    srcs = ["thread_module.cc"],
+    deps = [
+        ":test_cc_proto",
+        "//pybind11_protobuf:native_proto_caster",
+        "@com_google_absl//absl/time",
+        "@com_google_protobuf//:protobuf",
+    ],
+)
+
+py_test(
+    name = "thread_module_test",
+    srcs = ["thread_module_test.py"],
+    data = [":thread_module.so"],
+    python_version = "PY3",
+    srcs_version = "PY3",
+    deps = [
+        "@com_google_absl_py//absl/testing:absltest",
+        "@com_google_absl_py//absl/testing:parameterized",
+    ],
+)

pybind11_protobuf/tests/thread_module.cc

@@ -0,0 +1,66 @@
+// Copyright (c) 2021 The Pybind Development Team. All rights reserved.
+//
+// All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include <pybind11/pybind11.h>
+
+#include <functional>
+#include <memory>
+#include <stdexcept>
+
+#include "google/protobuf/dynamic_message.h"
+#include "absl/time/clock.h"
+#include "absl/time/time.h"
+#include "pybind11_protobuf/native_proto_caster.h"
+#include "pybind11_protobuf/tests/test.pb.h"
+
+namespace py = ::pybind11;
+
+using pybind11::test::TestMessage;
+
+namespace {
+
+PYBIND11_MODULE(thread_module, m) {
+  m.def(
+      "make_message",
+      [](std::string text) -> TestMessage {
+        absl::SleepFor(absl::Milliseconds(1));
+        TestMessage msg;
+        msg.set_string_value(std::move(text));
+        return msg;
+      },
+      py::arg("text") = "");
+
+  m.def(
+      "make_message_string_view",
+      [](std::string_view text) -> TestMessage {
+        absl::SleepFor(absl::Milliseconds(1));
+        TestMessage msg;
+        msg.set_string_value(std::string(text));
+        return msg;
+      },
+      py::arg("text") = "");
+
+  m.def(
+      "make_message_no_gil",
+      [](std::string text) -> TestMessage {
+        absl::SleepFor(absl::Milliseconds(1));
+        TestMessage msg;
+        msg.set_string_value(std::move(text));
+        return msg;
+      },
+      py::arg("text") = "", py::call_guard<py::gil_scoped_release>());
+
+  m.def(
+      "make_message_string_view_no_gil",
+      [](std::string_view text) -> TestMessage {
+        absl::SleepFor(absl::Milliseconds(1));
+        TestMessage msg;
+        msg.set_string_value(std::string(text));
+        return msg;
+      },
+      py::arg("text") = "", py::call_guard<py::gil_scoped_release>());
+}
+
+}  // namespace

pybind11_protobuf/tests/thread_module_test.py

@@ -0,0 +1,34 @@
+"""Test pybind11_protobuf with multiple threads.
+
+Run with `blaze test :thread_test --config=tsan`.
+"""
+
+import multiprocessing.pool
+
+from absl.testing import absltest
+from absl.testing import parameterized
+from pybind11_protobuf.tests import thread_module as m
+
+
+class ThreadTest(parameterized.TestCase):
+
+  @parameterized.named_parameters(
+      ('make_message', m.make_message),
+      ('make_message_string_view', m.make_message_string_view),
+      ('make_message_no_gil', m.make_message_no_gil),
+      # BUG: https://github.com/pybind/pybind11/issues/2765
+      # The following fails due to std::string_view casting in pybind11
+      # ('make_message_string_view_no_gil', m.make_message_string_view_no_gil),
+  )
+  def test_parallel(self, fn):
+    data = ['abc'] * 10
+    with multiprocessing.pool.ThreadPool(4) as pool:
+      result = list(pool.map(fn, data))
+    pool.close()
+    pool.join()
+    for x in result:
+      self.assertEqual('abc', x.string_value)
+
+
+if __name__ == '__main__':
+  absltest.main()