Merge pull request #12719 from grpc/revert-12580-execp

Revert "General executor speedups, introspection"

1 files changed, 30 insertions, 39 deletions

diff --git a/src/core/lib/iomgr/executor.c b/src/core/lib/iomgr/executor.c
index 2439f15a8a..892385d7d7 100644
--- a/src/core/lib/iomgr/executor.c
+++ b/src/core/lib/iomgr/executor.c
@@ -32,14 +32,16 @@
 #include "src/core/lib/iomgr/exec_ctx.h"
 #include "src/core/lib/support/spinlock.h"
 
+#define MAX_DEPTH 2
+
 typedef struct {
   gpr_mu mu;
   gpr_cv cv;
   grpc_closure_list elems;
+  size_t depth;
   bool shutdown;
   bool queued_long_job;
   gpr_thd_id id;
-  grpc_closure_list local_elems;
 } thread_state;
 
 static thread_state *g_thread_state;
@@ -54,35 +56,32 @@ static grpc_tracer_flag executor_trace =
 
 static void executor_thread(void *arg);
 
-static void run_closures(grpc_exec_ctx *exec_ctx, grpc_closure_list *list) {
-  int n = 0;  // number of closures executed
+static size_t run_closures(grpc_exec_ctx *exec_ctx, grpc_closure_list list) {
+  size_t n = 0;
 
-  while (!grpc_closure_list_empty(*list)) {
-    grpc_closure *c = list->head;
-    grpc_closure_list_init(list);
-    while (c != NULL) {
-      grpc_closure *next = c->next_data.next;
-      grpc_error *error = c->error_data.error;
-      if (GRPC_TRACER_ON(executor_trace)) {
+  grpc_closure *c = list.head;
+  while (c != NULL) {
+    grpc_closure *next = c->next_data.next;
+    grpc_error *error = c->error_data.error;
+    if (GRPC_TRACER_ON(executor_trace)) {
 #ifndef NDEBUG
-        gpr_log(GPR_DEBUG, "EXECUTOR: run %p [created by %s:%d]", c,
-                c->file_created, c->line_created);
+      gpr_log(GPR_DEBUG, "EXECUTOR: run %p [created by %s:%d]", c,
+              c->file_created, c->line_created);
 #else
-        gpr_log(GPR_DEBUG, "EXECUTOR: run %p", c);
+      gpr_log(GPR_DEBUG, "EXECUTOR: run %p", c);
 #endif
-      }
+    }
 #ifndef NDEBUG
-      c->scheduled = false;
+    c->scheduled = false;
 #endif
-      n++;
-      c->cb(exec_ctx, c->cb_arg, error);
-      GRPC_ERROR_UNREF(error);
-      c = next;
-      grpc_exec_ctx_flush(exec_ctx);
-    }
+    c->cb(exec_ctx, c->cb_arg, error);
+    GRPC_ERROR_UNREF(error);
+    c = next;
+    n++;
+    grpc_exec_ctx_flush(exec_ctx);
   }
 
-  GRPC_STATS_INC_EXECUTOR_CLOSURES_PER_WAKEUP(exec_ctx, n);
+  return n;
 }
 
 bool grpc_executor_is_threaded() {
@@ -127,7 +126,7 @@ void grpc_executor_set_threading(grpc_exec_ctx *exec_ctx, bool threading) {
     for (size_t i = 0; i < g_max_threads; i++) {
       gpr_mu_destroy(&g_thread_state[i].mu);
       gpr_cv_destroy(&g_thread_state[i].cv);
-      run_closures(exec_ctx, &g_thread_state[i].elems);
+      run_closures(exec_ctx, g_thread_state[i].elems);
     }
     gpr_free(g_thread_state);
     gpr_tls_destroy(&g_this_thread_state);
@@ -151,14 +150,14 @@ static void executor_thread(void *arg) {
   grpc_exec_ctx exec_ctx =
       GRPC_EXEC_CTX_INITIALIZER(0, grpc_never_ready_to_finish, NULL);
 
-  GRPC_STATS_INC_EXECUTOR_THREADS_CREATED(&exec_ctx);
-
-  bool used = false;
+  size_t subtract_depth = 0;
   for (;;) {
     if (GRPC_TRACER_ON(executor_trace)) {
-      gpr_log(GPR_DEBUG, "EXECUTOR[%d]: step", (int)(ts - g_thread_state));
+      gpr_log(GPR_DEBUG, "EXECUTOR[%d]: step (sub_depth=%" PRIdPTR ")",
+              (int)(ts - g_thread_state), subtract_depth);
     }
     gpr_mu_lock(&ts->mu);
+    ts->depth -= subtract_depth;
     while (grpc_closure_list_empty(ts->elems) && !ts->shutdown) {
       ts->queued_long_job = false;
       gpr_cv_wait(&ts->cv, &ts->mu, gpr_inf_future(GPR_CLOCK_REALTIME));
@@ -171,20 +170,15 @@ static void executor_thread(void *arg) {
       gpr_mu_unlock(&ts->mu);
       break;
     }
-    if (!used) {
-      GRPC_STATS_INC_EXECUTOR_THREADS_USED(&exec_ctx);
-      used = true;
-    }
     GRPC_STATS_INC_EXECUTOR_QUEUE_DRAINED(&exec_ctx);
-    GPR_ASSERT(grpc_closure_list_empty(ts->local_elems));
-    ts->local_elems = ts->elems;
+    grpc_closure_list exec = ts->elems;
     ts->elems = (grpc_closure_list)GRPC_CLOSURE_LIST_INIT;
     gpr_mu_unlock(&ts->mu);
     if (GRPC_TRACER_ON(executor_trace)) {
       gpr_log(GPR_DEBUG, "EXECUTOR[%d]: execute", (int)(ts - g_thread_state));
     }
 
-    run_closures(&exec_ctx, &ts->local_elems);
+    subtract_depth = run_closures(&exec_ctx, exec);
   }
   grpc_exec_ctx_finish(&exec_ctx);
 }
@@ -217,10 +211,6 @@ static void executor_push(grpc_exec_ctx *exec_ctx, grpc_closure *closure,
       ts = &g_thread_state[GPR_HASH_POINTER(exec_ctx, cur_thread_count)];
     } else {
       GRPC_STATS_INC_EXECUTOR_SCHEDULED_TO_SELF(exec_ctx);
-      if (is_short) {
-        grpc_closure_list_append(&ts->local_elems, closure, error);
-        return;
-      }
     }
     thread_state *orig_ts = ts;
 
@@ -260,7 +250,8 @@ static void executor_push(grpc_exec_ctx *exec_ctx, grpc_closure *closure,
         gpr_cv_signal(&ts->cv);
       }
       grpc_closure_list_append(&ts->elems, closure, error);
-      try_new_thread = ts->elems.head != closure &&
+      ts->depth++;
+      try_new_thread = ts->depth > MAX_DEPTH &&
                        cur_thread_count < g_max_threads && !ts->shutdown;
       if (!is_short) ts->queued_long_job = true;
       gpr_mu_unlock(&ts->mu);