--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/test/benchmark-million-async.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,113 @@
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "task.h"
+#include "uv.h"
+
+struct async_container {
+  unsigned async_events;
+  unsigned handles_seen;
+  uv_async_t async_handles[1024 * 1024];
+};
+
+static volatile int done;
+static uv_thread_t thread_id;
+static struct async_container* container;
+
+
+static unsigned fastrand(void) {
+  static unsigned g = 0;
+  g = g * 214013 + 2531011;
+  return g;
+}
+
+
+static void thread_cb(void* arg) {
+  unsigned i;
+
+  while (done == 0) {
+    i = fastrand() % ARRAY_SIZE(container->async_handles);
+    uv_async_send(container->async_handles + i);
+  }
+}
+
+
+static void async_cb(uv_async_t* handle) {
+  container->async_events++;
+  handle->data = handle;
+}
+
+
+static void timer_cb(uv_timer_t* handle) {
+  unsigned i;
+
+  done = 1;
+  ASSERT_OK(uv_thread_join(&thread_id));
+
+  for (i = 0; i < ARRAY_SIZE(container->async_handles); i++) {
+    uv_async_t* handle = container->async_handles + i;
+
+    if (handle->data != NULL)
+      container->handles_seen++;
+
+    uv_close((uv_handle_t*) handle, NULL);
+  }
+
+  uv_close((uv_handle_t*) handle, NULL);
+}
+
+
+BENCHMARK_IMPL(million_async) {
+  char fmtbuf[3][32];
+  uv_timer_t timer_handle;
+  uv_async_t* handle;
+  uv_loop_t* loop;
+  int timeout;
+  unsigned i;
+
+  loop = uv_default_loop();
+  timeout = 5000;
+
+  container = malloc(sizeof(*container));
+  ASSERT_NOT_NULL(container);
+  container->async_events = 0;
+  container->handles_seen = 0;
+
+  for (i = 0; i < ARRAY_SIZE(container->async_handles); i++) {
+    handle = container->async_handles + i;
+    ASSERT_OK(uv_async_init(loop, handle, async_cb));
+    handle->data = NULL;
+  }
+
+  ASSERT_OK(uv_timer_init(loop, &timer_handle));
+  ASSERT_OK(uv_timer_start(&timer_handle, timer_cb, timeout, 0));
+  ASSERT_OK(uv_thread_create(&thread_id, thread_cb, NULL));
+  ASSERT_OK(uv_run(loop, UV_RUN_DEFAULT));
+  printf("%s async events in %.1f seconds (%s/s, %s unique handles seen)\n",
+          fmt(&fmtbuf[0], container->async_events),
+          timeout / 1000.,
+          fmt(&fmtbuf[1], container->async_events / (timeout / 1000.)),
+          fmt(&fmtbuf[2], container->handles_seen));
+  free(container);
+
+  MAKE_VALGRIND_HAPPY(loop);
+  return 0;
+}