Add thread name prefix to the default thread pool executor (#636)

---------

Co-authored-by: Fantix King <fantix.king@gmail.com>

Author: inikolaev

tests/test_base.py

@@ -799,6 +799,26 @@ async def main():
         elif result.returncode != 0:
             self.fail(result.stdout.strip())
 
+    def test_thread_name_prefix_in_default_executor(self):
+        if self.implementation == "asyncio" and sys.version_info < (3, 9):
+            raise unittest.SkipTest(
+                "thread_name_prefix was added in CPython 3.9"
+            )
+
+        called = []
+
+        def cb():
+            called.append(threading.current_thread().name)
+
+        async def runner():
+            await self.loop.run_in_executor(None, cb)
+
+        self.loop.run_until_complete(runner())
+
+        self.assertEqual(len(called), 1)
+        self.assertTrue(called[0] is not None)
+        self.assertTrue(called[0].startswith(self.implementation))
+
 
 class TestBaseUV(_TestBase, UVTestCase):
 

uvloop/loop.pyx

@@ -2747,7 +2747,7 @@ cdef class Loop:
             # Only check when the default executor is being used
             self._check_default_executor()
             if executor is None:
-                executor = cc_ThreadPoolExecutor()
+                executor = cc_ThreadPoolExecutor(thread_name_prefix='uvloop')
                 self._default_executor = executor
 
         return aio_wrap_future(executor.submit(func, *args), loop=self)