Add a counter for spurious writes

src/core/ext/transport/chttp2/transport/chttp2_transport.c

@@ -1027,6 +1027,7 @@ static void write_action_begin_locked(grpc_exec_ctx *exec_ctx, void *gt,
                                                    write_action, t, scheduler),
                        GRPC_ERROR_NONE);
   } else {
+    GRPC_STATS_INC_HTTP2_SPURIOUS_WRITES_BEGUN(exec_ctx);
     set_write_state(exec_ctx, t, GRPC_CHTTP2_WRITE_STATE_IDLE,
                     "begin writing nothing");
     GRPC_CHTTP2_UNREF_TRANSPORT(exec_ctx, t, "writing");

src/core/lib/debug/stats_data.c

@@ -71,6 +71,7 @@ const char *grpc_stats_counter_name[GRPC_STATS_COUNTER_COUNT] = {
     "http2_initiate_write_due_to_transport_flow_control_unstalled",
     "http2_initiate_write_due_to_ping_response",
     "http2_initiate_write_due_to_force_rst_stream",
+    "http2_spurious_writes_begun",
     "combiner_locks_initiated",
     "combiner_locks_scheduled_items",
     "combiner_locks_scheduled_final_items",
@@ -137,6 +138,7 @@ const char *grpc_stats_counter_doc[GRPC_STATS_COUNTER_COUNT] = {
     "'transport_flow_control_unstalled'",
     "Number of HTTP2 writes initiated due to 'ping_response'",
     "Number of HTTP2 writes initiated due to 'force_rst_stream'",
+    "Number of HTTP2 writes initiated with nothing to write",
     "Number of combiner lock entries by process (first items queued to a "
     "combiner)",
     "Number of items scheduled against combiner locks",

src/core/lib/debug/stats_data.h

@@ -73,6 +73,7 @@ typedef enum {
   GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL_UNSTALLED,
   GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_PING_RESPONSE,
   GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FORCE_RST_STREAM,
+  GRPC_STATS_COUNTER_HTTP2_SPURIOUS_WRITES_BEGUN,
   GRPC_STATS_COUNTER_COMBINER_LOCKS_INITIATED,
   GRPC_STATS_COUNTER_COMBINER_LOCKS_SCHEDULED_ITEMS,
   GRPC_STATS_COUNTER_COMBINER_LOCKS_SCHEDULED_FINAL_ITEMS,
@@ -279,6 +280,9 @@ typedef enum {
   GRPC_STATS_INC_COUNTER(                                                     \
       (exec_ctx),                                                             \
       GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FORCE_RST_STREAM)
+#define GRPC_STATS_INC_HTTP2_SPURIOUS_WRITES_BEGUN(exec_ctx) \
+  GRPC_STATS_INC_COUNTER((exec_ctx),                         \
+                         GRPC_STATS_COUNTER_HTTP2_SPURIOUS_WRITES_BEGUN)
 #define GRPC_STATS_INC_COMBINER_LOCKS_INITIATED(exec_ctx) \
   GRPC_STATS_INC_COUNTER((exec_ctx),                      \
                          GRPC_STATS_COUNTER_COMBINER_LOCKS_INITIATED)

src/core/lib/debug/stats_data.yaml

@@ -159,6 +159,8 @@
   doc: Number of HTTP2 writes initiated due to 'ping_response'
 - counter: http2_initiate_write_due_to_force_rst_stream
   doc: Number of HTTP2 writes initiated due to 'force_rst_stream'
+- counter: http2_spurious_writes_begun
+  doc: Number of HTTP2 writes initiated with nothing to write
 # combiner locks
 - counter: combiner_locks_initiated
   doc: Number of combiner lock entries by process

src/core/lib/debug/stats_data_bq_schema.sql

@@ -46,6 +46,7 @@ http2_initiate_write_due_to_keepalive_ping_per_iteration:FLOAT,
 http2_initiate_write_due_to_transport_flow_control_unstalled_per_iteration:FLOAT,
 http2_initiate_write_due_to_ping_response_per_iteration:FLOAT,
 http2_initiate_write_due_to_force_rst_stream_per_iteration:FLOAT,
+http2_spurious_writes_begun_per_iteration:FLOAT,
 combiner_locks_initiated_per_iteration:FLOAT,
 combiner_locks_scheduled_items_per_iteration:FLOAT,
 combiner_locks_scheduled_final_items_per_iteration:FLOAT,

tools/run_tests/performance/massage_qps_stats.py

@@ -68,6 +68,7 @@ def massage_qps_stats(scenario_result):
     stats["core_http2_initiate_write_due_to_transport_flow_control_unstalled"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_transport_flow_control_unstalled")
     stats["core_http2_initiate_write_due_to_ping_response"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_ping_response")
     stats["core_http2_initiate_write_due_to_force_rst_stream"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_force_rst_stream")
+    stats["core_http2_spurious_writes_begun"] = massage_qps_stats_helpers.counter(core_stats, "http2_spurious_writes_begun")
     stats["core_combiner_locks_initiated"] = massage_qps_stats_helpers.counter(core_stats, "combiner_locks_initiated")
     stats["core_combiner_locks_scheduled_items"] = massage_qps_stats_helpers.counter(core_stats, "combiner_locks_scheduled_items")
     stats["core_combiner_locks_scheduled_final_items"] = massage_qps_stats_helpers.counter(core_stats, "combiner_locks_scheduled_final_items")

tools/run_tests/performance/scenario_result_schema.json

@@ -350,6 +350,11 @@
         "name": "core_http2_initiate_write_due_to_force_rst_stream", 
         "type": "INTEGER"
       }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_spurious_writes_begun", 
+        "type": "INTEGER"
+      }, 
       {
         "mode": "NULLABLE", 
         "name": "core_combiner_locks_initiated", 
@@ -952,6 +957,11 @@
         "name": "core_http2_initiate_write_due_to_force_rst_stream", 
         "type": "INTEGER"
       }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_spurious_writes_begun", 
+        "type": "INTEGER"
+      }, 
       {
         "mode": "NULLABLE", 
         "name": "core_combiner_locks_initiated",