[pick_first] enable pick_first_ready_to_connecting experiment (#41475)

This should be a no-op unless subchannel connection scaling is enabled, and that's controlled by a separate experiment.

See #41029 for implementation.

Closes #41475

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/41475 from markdroth:pf_experiment_enable a2d316b447
PiperOrigin-RevId: 860319677

bazel/experiments.bzl

@@ -114,7 +114,6 @@ EXPERIMENTS = {
                 "promise_based_http2_client_transport",
             ],
             "cpp_lb_end2end_test": [
-                "pick_first_ready_to_connecting",
                 "subchannel_connection_scaling",
             ],
             "endpoint_test": [
@@ -132,9 +131,6 @@ EXPERIMENTS = {
                 "tcp_frame_size_tuning",
                 "tcp_rcv_lowat",
             ],
-            "lb_unit_test": [
-                "pick_first_ready_to_connecting",
-            ],
             "minimal_stack_test": [
                 "fuse_filters",
             ],
@@ -172,6 +168,7 @@ EXPERIMENTS = {
                 "event_engine_secure_endpoint",
             ],
             "cpp_lb_end2end_test": [
+                "pick_first_ready_to_connecting",
                 "rr_wrr_connect_from_random_index",
             ],
             "event_engine_client_test": [
@@ -181,6 +178,7 @@ EXPERIMENTS = {
                 "event_engine_listener",
             ],
             "lb_unit_test": [
+                "pick_first_ready_to_connecting",
                 "rr_wrr_connect_from_random_index",
             ],
             "posix_endpoint_test": [
@@ -227,7 +225,6 @@ EXPERIMENTS = {
                 "promise_based_http2_client_transport",
             ],
             "cpp_lb_end2end_test": [
-                "pick_first_ready_to_connecting",
                 "subchannel_connection_scaling",
             ],
             "endpoint_test": [
@@ -245,9 +242,6 @@ EXPERIMENTS = {
                 "tcp_frame_size_tuning",
                 "tcp_rcv_lowat",
             ],
-            "lb_unit_test": [
-                "pick_first_ready_to_connecting",
-            ],
             "minimal_stack_test": [
                 "fuse_filters",
             ],
@@ -285,6 +279,7 @@ EXPERIMENTS = {
                 "event_engine_secure_endpoint",
             ],
             "cpp_lb_end2end_test": [
+                "pick_first_ready_to_connecting",
                 "rr_wrr_connect_from_random_index",
             ],
             "event_engine_client_test": [
@@ -294,6 +289,7 @@ EXPERIMENTS = {
                 "event_engine_listener",
             ],
             "lb_unit_test": [
+                "pick_first_ready_to_connecting",
                 "rr_wrr_connect_from_random_index",
             ],
             "posix_endpoint_test": [
@@ -340,7 +336,6 @@ EXPERIMENTS = {
                 "promise_based_http2_client_transport",
             ],
             "cpp_lb_end2end_test": [
-                "pick_first_ready_to_connecting",
                 "subchannel_connection_scaling",
             ],
             "endpoint_test": [
@@ -358,9 +353,6 @@ EXPERIMENTS = {
                 "tcp_frame_size_tuning",
                 "tcp_rcv_lowat",
             ],
-            "lb_unit_test": [
-                "pick_first_ready_to_connecting",
-            ],
             "minimal_stack_test": [
                 "fuse_filters",
             ],
@@ -398,6 +390,7 @@ EXPERIMENTS = {
                 "event_engine_secure_endpoint",
             ],
             "cpp_lb_end2end_test": [
+                "pick_first_ready_to_connecting",
                 "rr_wrr_connect_from_random_index",
             ],
             "event_engine_client_test": [
@@ -407,6 +400,7 @@ EXPERIMENTS = {
                 "event_engine_listener",
             ],
             "lb_unit_test": [
+                "pick_first_ready_to_connecting",
                 "rr_wrr_connect_from_random_index",
             ],
             "posix_endpoint_test": [

src/core/lib/experiments/experiments.cc

@@ -323,7 +323,7 @@ const ExperimentMetadata g_experiment_metadata[] = {
      true},
     {"pick_first_ready_to_connecting",
      description_pick_first_ready_to_connecting,
-     additional_constraints_pick_first_ready_to_connecting, nullptr, 0, false,
+     additional_constraints_pick_first_ready_to_connecting, nullptr, 0, true,
      true},
     {"pipelined_read_secure_endpoint",
      description_pipelined_read_secure_endpoint,
@@ -714,7 +714,7 @@ const ExperimentMetadata g_experiment_metadata[] = {
      true},
     {"pick_first_ready_to_connecting",
      description_pick_first_ready_to_connecting,
-     additional_constraints_pick_first_ready_to_connecting, nullptr, 0, false,
+     additional_constraints_pick_first_ready_to_connecting, nullptr, 0, true,
      true},
     {"pipelined_read_secure_endpoint",
      description_pipelined_read_secure_endpoint,
@@ -1105,7 +1105,7 @@ const ExperimentMetadata g_experiment_metadata[] = {
      true},
     {"pick_first_ready_to_connecting",
      description_pick_first_ready_to_connecting,
-     additional_constraints_pick_first_ready_to_connecting, nullptr, 0, false,
+     additional_constraints_pick_first_ready_to_connecting, nullptr, 0, true,
      true},
     {"pipelined_read_secure_endpoint",
      description_pipelined_read_secure_endpoint,

src/core/lib/experiments/experiments.h

@@ -100,7 +100,8 @@ inline bool IsMonitoringExperimentEnabled() { return true; }
 inline bool IsMultipingEnabled() { return false; }
 inline bool IsOtelExportTelemetryDomainsEnabled() { return false; }
 inline bool IsPickFirstIgnoreEmptyUpdatesEnabled() { return false; }
-inline bool IsPickFirstReadyToConnectingEnabled() { return false; }
+#define GRPC_EXPERIMENT_IS_INCLUDED_PICK_FIRST_READY_TO_CONNECTING
+inline bool IsPickFirstReadyToConnectingEnabled() { return true; }
 inline bool IsPipelinedReadSecureEndpointEnabled() { return false; }
 inline bool IsPollsetAlternativeEnabled() { return false; }
 inline bool IsPrioritizeFinishedRequestsEnabled() { return false; }
@@ -172,7 +173,8 @@ inline bool IsMonitoringExperimentEnabled() { return true; }
 inline bool IsMultipingEnabled() { return false; }
 inline bool IsOtelExportTelemetryDomainsEnabled() { return false; }
 inline bool IsPickFirstIgnoreEmptyUpdatesEnabled() { return false; }
-inline bool IsPickFirstReadyToConnectingEnabled() { return false; }
+#define GRPC_EXPERIMENT_IS_INCLUDED_PICK_FIRST_READY_TO_CONNECTING
+inline bool IsPickFirstReadyToConnectingEnabled() { return true; }
 inline bool IsPipelinedReadSecureEndpointEnabled() { return false; }
 inline bool IsPollsetAlternativeEnabled() { return false; }
 inline bool IsPrioritizeFinishedRequestsEnabled() { return false; }
@@ -244,7 +246,8 @@ inline bool IsMonitoringExperimentEnabled() { return true; }
 inline bool IsMultipingEnabled() { return false; }
 inline bool IsOtelExportTelemetryDomainsEnabled() { return false; }
 inline bool IsPickFirstIgnoreEmptyUpdatesEnabled() { return false; }
-inline bool IsPickFirstReadyToConnectingEnabled() { return false; }
+#define GRPC_EXPERIMENT_IS_INCLUDED_PICK_FIRST_READY_TO_CONNECTING
+inline bool IsPickFirstReadyToConnectingEnabled() { return true; }
 inline bool IsPipelinedReadSecureEndpointEnabled() { return false; }
 inline bool IsPollsetAlternativeEnabled() { return false; }
 inline bool IsPrioritizeFinishedRequestsEnabled() { return false; }

src/core/lib/experiments/rollouts.yaml

@@ -82,6 +82,8 @@
   default: true
 - name: monitoring_experiment
   default: true
+- name: pick_first_ready_to_connecting
+  default: true
 - name: pollset_alternative
   default: false
 - name: prioritize_finished_requests