apache · bneradt · Nov 6, 2025
diff --git a/tests/gold_tests/autest-site/verifier_client.test.ext b/tests/gold_tests/autest-site/verifier_client.test.ext
@@ -34,6 +34,7 @@ def _configure_client(
         ca_cert='',
         verbose=True,
         other_args='',
+        run_parallel=False,
         context=None):
     """
     Configure the process for running the verifier-client.
@@ -70,7 +71,7 @@ def _configure_client(
         # Create a copy of the replay directory in the run directory.
         run_replay_path = os.path.join(client_dir, os.path.basename(replay_path))
         process.Setup.Copy(replay_path, run_replay_path, CopyLogic.SoftFiles)
-        command += " {} ".format(run_replay_path)
+        command += f" {run_replay_path} "
 
     if not http_ports:
         http_ports = [8080]
@@ -103,12 +104,12 @@ def _configure_client(
             ssl_cert = os.path.join(obj.Variables["AtsTestToolsDir"], "proxy-verifier", "ssl", "client.pem")
 
             if not os.path.isfile(ssl_cert):
-                raise ValueError("Tried to use '{}' for --client-cert, but it is not "
-                                 "a valid file.".format(ssl_cert))
+                raise ValueError(f"Tried to use '{ssl_cert}' for --client-cert, but it is not "
+                                 "a valid file.")
         if ssl_cert:
             run_ssl_cert = os.path.join(client_dir, os.path.basename(ssl_cert))
             process.Setup.Copy(ssl_cert, run_ssl_cert, CopyLogic.SoftFiles)
-            command += ' --client-cert "{}" '.format(run_ssl_cert)
+            command += f' --client-cert "{run_ssl_cert}" '
 
             tls_secrets_log_filename = "tls_secrets.txt"
             tls_secrets_log_path = os.path.join(client_dir, tls_secrets_log_filename)
@@ -119,21 +120,26 @@ def _configure_client(
             ca_cert = os.path.join(obj.Variables["AtsTestToolsDir"], "proxy-verifier", "ssl", "ca.pem")
 
             if not os.path.isfile(ca_cert):
-                raise ValueError("Tried to use '{}' for --ca-certs, but it is not "
-                                 "a valid file.".format(ca_cert))
+                raise ValueError(f"Tried to use '{ca_cert}' for --ca-certs, but it is not "
+                                 "a valid file.")
         if ca_cert:
             run_ca_cert = os.path.join(client_dir, os.path.basename(ca_cert))
             process.Setup.Copy(ca_cert, run_ca_cert, CopyLogic.SoftFiles)
-            command += ' --ca-certs "{}" '.format(run_ca_cert)
+            command += f' --ca-certs "{run_ca_cert}" '
 
     if verbose:
         command += ' --verbose diag '
 
     if other_args:
-        command += " {}".format(other_args)
+        command += f" {other_args}"
 
     if keys is not None:
-        command += " --keys {}".format(keys)
+        command += f" --keys {keys}"
+
+    # Generally we prefer the deterministic behavior of a single thread where
+    # each connection is processed sequentially.
+    if not run_parallel and 'thread-limit' not in command:
+        command += " --thread-limit 1"
 
     process.Command = command
     process.ReturnCode = 0
@@ -154,6 +160,7 @@ def AddVerifierClientProcess(
         ca_cert='',
         verbose=True,
         other_args='',
+        run_parallel=False,
         context=None):
     """
     Set the Default process of the test run to a verifier-client Process.
@@ -184,6 +191,8 @@ def AddVerifierClientProcess(
 
         other_args: (str) Any other arbitrary options to pass to verifier-client.
 
+        run_parallel: (bool) Whether to run the verifier-client in parallel.
+
         context: Any dictionary-like object with keys that match the placeholders
                  in the replay file.
                  Template strings support $-based substitutions in the replay file.
@@ -203,7 +212,8 @@ def AddVerifierClientProcess(
 
     p = run.Processes.Default
     _configure_client(
-        run, p, name, replay_path, http_ports, https_ports, http3_ports, keys, ssl_cert, ca_cert, verbose, other_args, context)
+        run, p, name, replay_path, http_ports, https_ports, http3_ports, keys, ssl_cert, ca_cert, verbose, other_args, run_parallel,
+        context)
     return p
 
 

diff --git a/tests/gold_tests/cache/background_fill.test.py b/tests/gold_tests/cache/background_fill.test.py
@@ -167,8 +167,7 @@ def __testCase3(self):
             "pv_client",
             "replay/bg_fill.yaml",
             http_ports=[self.ts['for_pv'].Variables.port],
-            https_ports=[self.ts['for_pv'].Variables.ssl_port],
-            other_args='--thread-limit 1')
+            https_ports=[self.ts['for_pv'].Variables.ssl_port])
         tr.Processes.Default.ReturnCode = 0
         tr.Processes.Default.Streams.stdout = "gold/background_fill_3_stdout.gold"
         self.__checkProcessAfter(tr)

diff --git a/tests/gold_tests/cache/cache-auth.test.py b/tests/gold_tests/cache/cache-auth.test.py
@@ -56,8 +56,7 @@ def runTraffic(self):
         tr = Test.AddTestRun(
             "Verify the proper caching behavior for request/response containing auth-related fields when ATS is in default configuration"
         )
-        tr.AddVerifierClientProcess(
-            "auth-default-client", self.authDefaultReplayFile, http_ports=[self.ts.Variables.port], other_args='--thread-limit 1')
+        tr.AddVerifierClientProcess("auth-default-client", self.authDefaultReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server
@@ -98,8 +97,7 @@ def runTraffic(self):
         tr = Test.AddTestRun(
             "Verify the proper caching behavior for request/response containing auth-related fields when ATS is configured to bypass caching for those"
         )
-        tr.AddVerifierClientProcess(
-            "auth-ignored-client", self.authIgnoredReplayFile, http_ports=[self.ts.Variables.port], other_args='--thread-limit 1')
+        tr.AddVerifierClientProcess("auth-ignored-client", self.authIgnoredReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server

diff --git a/tests/gold_tests/cache/cache-control.test.py b/tests/gold_tests/cache/cache-control.test.py
@@ -203,10 +203,7 @@ def setupTS(self):
     def runTraffic(self):
         tr = Test.AddTestRun("Verify the proper handling of cache-control directives in requests in default configuration")
         tr.AddVerifierClientProcess(
-            "request-cache-control-default-client",
-            self.requestCacheControlReplayFile,
-            http_ports=[self.ts.Variables.port],
-            other_args='--thread-limit 1')
+            "request-cache-control-default-client", self.requestCacheControlReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server
@@ -256,10 +253,7 @@ def runTraffic(self):
             "Verify the proper handling of cache-control directives in requests when ATS is configured to honor client's request to bypass the cache"
         )
         tr.AddVerifierClientProcess(
-            "request-cache-control-honor-client-client",
-            self.requestCacheControlReplayFile,
-            http_ports=[self.ts.Variables.port],
-            other_args='--thread-limit 1')
+            "request-cache-control-honor-client-client", self.requestCacheControlReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server
@@ -304,10 +298,7 @@ def setupTS(self):
     def runTraffic(self):
         tr = Test.AddTestRun("Verify the proper handling of cache-control directives in responses in default configuration")
         tr.AddVerifierClientProcess(
-            "response-cache-control-client-default",
-            self.responseCacheControlReplayFile,
-            http_ports=[self.ts.Variables.port],
-            other_args='--thread-limit 1')
+            "response-cache-control-client-default", self.responseCacheControlReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server
@@ -356,10 +347,7 @@ def runTraffic(self):
             "Verify the proper handling of cache-control directives in responses when ATS is configured to ignore server's request to bypass the cache"
         )
         tr.AddVerifierClientProcess(
-            "response-cache-control-client-ignored",
-            self.responseCacheControlReplayFile,
-            http_ports=[self.ts.Variables.port],
-            other_args='--thread-limit 1')
+            "response-cache-control-client-ignored", self.responseCacheControlReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server

diff --git a/tests/gold_tests/cache/cache-cookie.test.py b/tests/gold_tests/cache/cache-cookie.test.py
@@ -48,11 +48,7 @@ def setupTS(self):
 
     def runTraffic(self):
         tr = Test.AddTestRun("Verify the correct caching behavior when ATS is in default configuration")
-        tr.AddVerifierClientProcess(
-            "cookie-default-client",
-            self.cookieDefaultReplayFile,
-            http_ports=[self.ts.Variables.port],
-            other_args='--thread-limit 1')
+        tr.AddVerifierClientProcess("cookie-default-client", self.cookieDefaultReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server
@@ -91,8 +87,7 @@ def setupTS(self):
     def runTraffic(self):
         tr = Test.AddTestRun(
             "Verify the correct caching behavior when ATS is configured to not cache response to cookie for any content type")
-        tr.AddVerifierClientProcess(
-            "cookie-bypass-client", self.cookieBypassReplayFile, http_ports=[self.ts.Variables.port], other_args='--thread-limit 1')
+        tr.AddVerifierClientProcess("cookie-bypass-client", self.cookieBypassReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server
@@ -131,11 +126,7 @@ def setupTS(self):
     def runTraffic(self):
         tr = Test.AddTestRun(
             "Verify the correct caching behavior when ATS is configured to cache response to cookie only for image content type")
-        tr.AddVerifierClientProcess(
-            "cookie-img-only-client",
-            self.cookieImgOnlyReplayFile,
-            http_ports=[self.ts.Variables.port],
-            other_args='--thread-limit 1')
+        tr.AddVerifierClientProcess("cookie-img-only-client", self.cookieImgOnlyReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server
@@ -175,10 +166,7 @@ def runTraffic(self):
         tr = Test.AddTestRun(
             "Verify the correct caching behavior when ATS is configured to cache response to cookie for all but text types")
         tr.AddVerifierClientProcess(
-            "cookie-all-but-text-client",
-            self.cookieAllButTextReplayFile,
-            http_ports=[self.ts.Variables.port],
-            other_args='--thread-limit 1')
+            "cookie-all-but-text-client", self.cookieAllButTextReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server
@@ -222,10 +210,7 @@ def runTraffic(self):
             "Verify the correct caching behavior when ATS is configured to cache all content types but text, but with a few exceptions for text types which would also be cached"
         )
         tr.AddVerifierClientProcess(
-            "cookie-all-but-text-with-excp-client",
-            self.cookieAllButTextReplayFile,
-            http_ports=[self.ts.Variables.port],
-            other_args='--thread-limit 1')
+            "cookie-all-but-text-with-excp-client", self.cookieAllButTextReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server

diff --git a/tests/gold_tests/chunked_encoding/bad_chunked_encoding.test.py b/tests/gold_tests/chunked_encoding/bad_chunked_encoding.test.py
@@ -102,11 +102,7 @@ def setupTS(self):
     def runChunkedTraffic(self):
         tr = Test.AddTestRun()
         tr.AddVerifierClientProcess(
-            "client1",
-            self.chunkedReplayFile,
-            http_ports=[self.ts.Variables.port],
-            https_ports=[self.ts.Variables.ssl_port],
-            other_args='--thread-limit 1')
+            "client1", self.chunkedReplayFile, http_ports=[self.ts.Variables.port], https_ports=[self.ts.Variables.ssl_port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server
@@ -162,11 +158,7 @@ def setupTS(self):
     def runChunkedTraffic(self):
         tr = Test.AddTestRun()
         tr.AddVerifierClientProcess(
-            "client2",
-            self.chunkedReplayFile,
-            http_ports=[self.ts.Variables.port],
-            https_ports=[self.ts.Variables.ssl_port],
-            other_args='--thread-limit 1')
+            "client2", self.chunkedReplayFile, http_ports=[self.ts.Variables.port], https_ports=[self.ts.Variables.ssl_port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server

diff --git a/tests/gold_tests/client_connection/per_client_connection_max.test.py b/tests/gold_tests/client_connection/per_client_connection_max.test.py
@@ -144,7 +144,11 @@ def _configure_client(self, tr: 'TestRun') -> None:
         """
         name = f'client{PerClientConnectionMaxTest._client_counter}'
         p = tr.AddVerifierClientProcess(
-            name, self._replay_file, http_ports=[self._ts.Variables.port], https_ports=[self._ts.Variables.ssl_port])
+            name,
+            self._replay_file,
+            http_ports=[self._ts.Variables.port],
+            https_ports=[self._ts.Variables.ssl_port],
+            run_parallel=True)
         PerClientConnectionMaxTest._client_counter += 1
 
         p.StartBefore(self._dns)

diff --git a/tests/gold_tests/connect/connect.test.py b/tests/gold_tests/connect/connect.test.py
@@ -149,8 +149,7 @@ def setupTS(self):
 
     def runTraffic(self):
         tr = Test.AddTestRun("Verify correct handling of CONNECT request")
-        tr.AddVerifierClientProcess(
-            "connect-client", self.connectReplayFile, http_ports=[self.ts.Variables.port], other_args='--thread-limit 1')
+        tr.AddVerifierClientProcess("connect-client", self.connectReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server
@@ -235,8 +234,7 @@ def setupTS(self):
 
     def runTraffic(self):
         tr = Test.AddTestRun("Verify correct handling of CONNECT request on HTTP/2")
-        tr.AddVerifierClientProcess(
-            "connect-client2", self.connectReplayFile, https_ports=[self.ts.Variables.ssl_port], other_args='--thread-limit 1')
+        tr.AddVerifierClientProcess("connect-client2", self.connectReplayFile, https_ports=[self.ts.Variables.ssl_port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server

diff --git a/tests/gold_tests/h2/h2get_with_body.test.py b/tests/gold_tests/h2/h2get_with_body.test.py
@@ -55,11 +55,7 @@
 tr.Processes.Default.StartBefore(pv_server)
 tr.Processes.Default.StartBefore(ts)
 tr.AddVerifierClientProcess(
-    "pv_client",
-    "h2get_with_body.yaml",
-    http_ports=[ts.Variables.port],
-    https_ports=[ts.Variables.ssl_port],
-    other_args='--thread-limit 1')
+    "pv_client", "h2get_with_body.yaml", http_ports=[ts.Variables.port], https_ports=[ts.Variables.ssl_port])
 tr.Processes.Default.ReturnCode = 0
 
 tr.Processes.Default.Streams.All += Testers.ContainsExpression(

diff --git a/tests/gold_tests/h2/http2_close_connection.test.py b/tests/gold_tests/h2/http2_close_connection.test.py
@@ -51,11 +51,7 @@
 tr.Processes.Default.StartBefore(pv_server)
 tr.Processes.Default.StartBefore(ts)
 tr.AddVerifierClientProcess(
-    "pv_client",
-    "http2_close_connection.yaml",
-    http_ports=[ts.Variables.port],
-    https_ports=[ts.Variables.ssl_port],
-    other_args='--thread-limit 1')
+    "pv_client", "http2_close_connection.yaml", http_ports=[ts.Variables.port], https_ports=[ts.Variables.ssl_port])
 tr.Processes.Default.ReturnCode = 0
 
 tr.Processes.Default.Streams.All += Testers.ContainsExpression(

diff --git a/tests/gold_tests/headers/invalid_range_header.test.py b/tests/gold_tests/headers/invalid_range_header.test.py
@@ -49,8 +49,7 @@ def setupTS(self):
 
     def runTraffic(self):
         tr = Test.AddTestRun()
-        tr.AddVerifierClientProcess(
-            "client1", self.invalidRangeRequestReplayFile, http_ports=[self.ts.Variables.port], other_args='--thread-limit 1')
+        tr.AddVerifierClientProcess("client1", self.invalidRangeRequestReplayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server

diff --git a/tests/gold_tests/pluginTest/access_control/access_control.test.py b/tests/gold_tests/pluginTest/access_control/access_control.test.py
@@ -67,11 +67,7 @@ def setupTS(self):
     def run(self):
         tr = Test.AddTestRun("Session Cookie")
         tr.AddVerifierClientProcess(
-            "verifier-client",
-            self.replayFile,
-            http_ports=[self.ts.Variables.port],
-            https_ports=[self.ts.Variables.ssl_port],
-            other_args='--thread-limit 1')
+            "verifier-client", self.replayFile, http_ports=[self.ts.Variables.port], https_ports=[self.ts.Variables.ssl_port])
         tr.Processes.Default.StartBefore(self.ts)
         tr.Processes.Default.StartBefore(self.server)
         tr.StillRunningAfter = self.ts

diff --git a/tests/gold_tests/pluginTest/certifier/certifier.test.py b/tests/gold_tests/pluginTest/certifier/certifier.test.py
@@ -65,11 +65,7 @@ def setupTS(self):
     def runHTTPSTraffic(self):
         tr = Test.AddTestRun("Test dynamic generation of certs")
         tr.AddVerifierClientProcess(
-            "client1",
-            self.httpsReplayFile,
-            http_ports=[self.ts.Variables.port],
-            https_ports=[self.ts.Variables.ssl_port],
-            other_args='--thread-limit 1')
+            "client1", self.httpsReplayFile, http_ports=[self.ts.Variables.port], https_ports=[self.ts.Variables.ssl_port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server
@@ -144,11 +140,7 @@ def setupTS(self):
     def runHTTPSTraffic(self):
         tr = Test.AddTestRun("Test dynamic generation of certs")
         tr.AddVerifierClientProcess(
-            "client2",
-            self.httpsReplayFile,
-            http_ports=[self.ts.Variables.port],
-            https_ports=[self.ts.Variables.ssl_port],
-            other_args='--thread-limit 1')
+            "client2", self.httpsReplayFile, http_ports=[self.ts.Variables.port], https_ports=[self.ts.Variables.ssl_port])
         tr.Processes.Default.StartBefore(self.server)
         tr.Processes.Default.StartBefore(self.ts)
         tr.StillRunningAfter = self.server

diff --git a/tests/gold_tests/pluginTest/compress/compress-content-type-params.test.py b/tests/gold_tests/pluginTest/compress/compress-content-type-params.test.py
@@ -57,8 +57,7 @@ def setupTS(self):
 
     def run(self):
         tr = Test.AddTestRun()
-        tr.AddVerifierClientProcess(
-            "verifier-client", self.replayFile, http_ports=[self.ts.Variables.port], other_args='--thread-limit 1')
+        tr.AddVerifierClientProcess("verifier-client", self.replayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.ts)
         tr.Processes.Default.StartBefore(self.server)
         tr.StillRunningAfter = self.ts

diff --git a/tests/gold_tests/pluginTest/compress/compress-range.test.py b/tests/gold_tests/pluginTest/compress/compress-range.test.py
@@ -63,8 +63,7 @@ def setupTS(self):
 
     def run(self):
         tr = Test.AddTestRun()
-        tr.AddVerifierClientProcess(
-            "verifier-client", self.replayFile, http_ports=[self.ts.Variables.port], other_args='--thread-limit 1')
+        tr.AddVerifierClientProcess("verifier-client", self.replayFile, http_ports=[self.ts.Variables.port])
         tr.Processes.Default.StartBefore(self.ts)
         tr.Processes.Default.StartBefore(self.server)
         tr.StillRunningAfter = self.ts

diff --git a/tests/gold_tests/pluginTest/ja3_fingerprint/ja3_fingerprint.test.py b/tests/gold_tests/pluginTest/ja3_fingerprint/ja3_fingerprint.test.py
@@ -143,11 +143,7 @@ def _configure_client(self, tr: 'TestRun') -> None:
         """
         name = f'client{self._client_counter}'
         p = tr.AddVerifierClientProcess(
-            name,
-            self._replay_file,
-            http_ports=[self._ts.Variables.port],
-            https_ports=[self._ts.Variables.ssl_port],
-            other_args='--thread-limit 1')
+            name, self._replay_file, http_ports=[self._ts.Variables.port], https_ports=[self._ts.Variables.ssl_port])
         JA3FingerprintTest._client_counter += 1
 
         p.StartBefore(self._dns)