Add an initial mark that clients could use to delay startup of requests

test/cpp/qps/client.h

@@ -359,7 +359,7 @@ class ClientImpl : public Client {
       gpr_log(GPR_INFO, "Connecting to %s", target.c_str());
       GPR_ASSERT(channel_->WaitForConnected(
           gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
-                       gpr_time_from_seconds(30, GPR_TIMESPAN))));
+                       gpr_time_from_seconds(300, GPR_TIMESPAN))));
       stub_ = create_stub(channel_);
     }
     Channel* get_channel() { return channel_.get(); }

test/cpp/qps/driver.cc

@@ -366,12 +366,37 @@ std::unique_ptr<ScenarioResult> RunScenario(
     if (!clients[i].stream->Write(args)) {
       gpr_log(GPR_ERROR, "Could not write args to client %zu", i);
     }
+  }
+
+  for (size_t i = 0; i < num_clients; i++) {
     ClientStatus init_status;
     if (!clients[i].stream->Read(&init_status)) {
       gpr_log(GPR_ERROR, "Client %zu did not yield initial status", i);
     }
   }
 
+  // Send an initial mark: clients can use this to know that everything is ready
+  // to start
+  gpr_log(GPR_INFO, "Initiating");
+  ServerArgs server_mark;
+  server_mark.mutable_mark()->set_reset(true);
+  ClientArgs client_mark;
+  client_mark.mutable_mark()->set_reset(true);
+  ServerStatus server_status;
+  ClientStatus client_status;
+  for (size_t i = 0; i < num_clients; i++) {
+    auto client = &clients[i];
+    if (!client->stream->Write(client_mark)) {
+      gpr_log(GPR_ERROR, "Couldn't write mark to client %zu", i);
+    }
+  }
+  for (size_t i = 0; i < num_clients; i++) {
+    auto client = &clients[i];
+    if (!client->stream->Read(&client_status)) {
+      gpr_log(GPR_ERROR, "Couldn't get status from client %zu", i);
+    }
+  }
+
   // Let everything warmup
   gpr_log(GPR_INFO, "Warming up");
   gpr_timespec start = gpr_now(GPR_CLOCK_REALTIME);
@@ -380,10 +405,6 @@ std::unique_ptr<ScenarioResult> RunScenario(
 
   // Start a run
   gpr_log(GPR_INFO, "Starting");
-  ServerArgs server_mark;
-  server_mark.mutable_mark()->set_reset(true);
-  ClientArgs client_mark;
-  client_mark.mutable_mark()->set_reset(true);
   for (size_t i = 0; i < num_servers; i++) {
     auto server = &servers[i];
     if (!server->stream->Write(server_mark)) {
@@ -396,8 +417,6 @@ std::unique_ptr<ScenarioResult> RunScenario(
       gpr_log(GPR_ERROR, "Couldn't write mark to client %zu", i);
     }
   }
-  ServerStatus server_status;
-  ClientStatus client_status;
   for (size_t i = 0; i < num_servers; i++) {
     auto server = &servers[i];
     if (!server->stream->Read(&server_status)) {