[experiments] Enable memory_pressure_controller for debug builds (#31811)

* [experiments] Enable memory_pressure_controller by default

* fix found crash

* fixy

bazel/experiments.bzl

@@ -24,6 +24,9 @@ EXPERIMENTS = {
         "hpack_test": [
             "new_hpack_huffman_decoder",
         ],
+        "resource_quota_test": [
+            "memory_pressure_controller",
+        ],
     },
     "off": {
         "core_end2end_test": [
@@ -45,7 +48,6 @@ EXPERIMENTS = {
             "promise_based_client_call",
         ],
         "resource_quota_test": [
-            "memory_pressure_controller",
             "unconstrained_max_quota_buffer_size",
         ],
     },

src/core/lib/experiments/experiments.cc

@@ -67,7 +67,7 @@ const ExperimentMetadata g_experiment_metadata[] = {
     {"peer_state_based_framing", description_peer_state_based_framing, false},
     {"flow_control_fixes", description_flow_control_fixes, true},
     {"memory_pressure_controller", description_memory_pressure_controller,
-     false},
+     kDefaultForDebugOnly},
     {"unconstrained_max_quota_buffer_size",
      description_unconstrained_max_quota_buffer_size, false},
     {"new_hpack_huffman_decoder", description_new_hpack_huffman_decoder,

src/core/lib/experiments/experiments.yaml

@@ -80,7 +80,7 @@
 - name: memory_pressure_controller
   description:
     New memory pressure controller
-  default: false
+  default: debug
   expiry: 2023/01/01
   owner: ctiller@google.com
   test_tags: [resource_quota_test]

src/core/lib/resource_quota/memory_quota.h

@@ -280,12 +280,12 @@ class BasicMemoryQuota final
   // Data about current memory pressure.
   struct PressureInfo {
     // The current instantaneously measured memory pressure.
-    double instantaneous_pressure;
+    double instantaneous_pressure = 0.0;
     // A control value that can be used to scale buffer sizes up or down to
     // adjust memory pressure to our target set point.
-    double pressure_control_value;
+    double pressure_control_value = 0.0;
     // Maximum recommended individual allocation size.
-    size_t max_recommended_allocation_size;
+    size_t max_recommended_allocation_size = 0;
   };
 
   explicit BasicMemoryQuota(std::string name) : name_(std::move(name)) {}
@@ -460,6 +460,7 @@ class MemoryOwner final : public MemoryAllocator {
 
   // Instantaneous memory pressure in the underlying quota.
   BasicMemoryQuota::PressureInfo GetPressureInfo() const {
+    if (!is_valid()) return BasicMemoryQuota::PressureInfo{};
     return impl()->GetPressureInfo();
   }