fix: isolate Appium session idempotency keys

appium/webdriver/appium_connection.py

@@ -56,10 +56,13 @@ def get_remote_connection_headers(cls, parsed_url: 'ParseResult', keep_alive: bo
         This method will be used in sending a request method in this class.
         """
 
+        extra_headers = cls.extra_headers.copy()
         if parsed_url.path.endswith('/session'):
             # https://github.com/appium/appium-base-driver/pull/400
-            cls.extra_headers[HEADER_IDEMOTENCY_KEY] = str(uuid.uuid4())
+            # Keep the per-request idempotency key local: sessions may be created concurrently.
+            extra_headers[HEADER_IDEMOTENCY_KEY] = str(uuid.uuid4())
         else:
-            cls.extra_headers = _get_new_headers(HEADER_IDEMOTENCY_KEY, cls.extra_headers)
+            extra_headers = _get_new_headers(HEADER_IDEMOTENCY_KEY, extra_headers)
+            cls.extra_headers = extra_headers
 
-        return {**super().get_remote_connection_headers(parsed_url, keep_alive=keep_alive), **cls.extra_headers}
+        return {**super().get_remote_connection_headers(parsed_url, keep_alive=keep_alive), **extra_headers}

test/unit/webdriver/appium_connection_test.py

@@ -1,4 +1,7 @@
+import threading
 import unittest
+from concurrent.futures import ThreadPoolExecutor
+from unittest.mock import patch
 from urllib import parse
 
 from appium.webdriver import appium_connection
@@ -30,6 +33,34 @@ def test_get_remote_connection_headers(self):
         self.assertIsNone(headers.get('X-Idempotency-Key'))
         self.assertEqual(headers.get('custom'), 'header')
 
+    def test_concurrent_new_sessions_get_distinct_idempotency_keys(self):
+        barrier = threading.Barrier(2)
+
+        def base_headers(cls, parsed_url, keep_alive=True):
+            barrier.wait(timeout=2)
+            return {}
+
+        appium_connection.AppiumConnection.extra_headers = {}
+        with (
+            patch.object(
+                appium_connection.RemoteConnection,
+                'get_remote_connection_headers',
+                new=classmethod(base_headers),
+            ),
+            ThreadPoolExecutor(max_workers=2) as pool,
+        ):
+            results = list(
+                pool.map(
+                    lambda _: appium_connection.AppiumConnection.get_remote_connection_headers(
+                        parse.urlparse('http://127.0.0.1:4723/session')
+                    ),
+                    range(2),
+                )
+            )
+
+        keys = [headers['X-Idempotency-Key'] for headers in results]
+        self.assertEqual(len(set(keys)), 2)
+
     def test_remove_headers_case_insensitive(self):
         for h in ['X-Idempotency-Key', 'X-idempotency-Key', 'x-idempotency-key']:
             appium_connection.AppiumConnection.extra_headers = {h: 'value'}