Fix misplaced unlock, cleanup tracing

src/core/lib/iomgr/timer_manager.c

@@ -37,6 +37,7 @@
 #include <grpc/support/log.h>
 #include <grpc/support/thd.h>
 
+#include "src/core/lib/debug/trace.h"
 #include "src/core/lib/iomgr/timer.h"
 
 typedef struct completed_thread {
@@ -44,6 +45,8 @@ typedef struct completed_thread {
   struct completed_thread *next;
 } completed_thread;
 
+extern grpc_tracer_flag grpc_timer_check_trace;
+
 // global mutex
 static gpr_mu g_mu;
 // are we multi-threaded
@@ -83,10 +86,13 @@ static void gc_completed_threads(void) {
 }
 
 static void start_timer_thread_and_unlock(void) {
+  GPR_ASSERT(g_threaded);
   ++g_waiter_count;
   ++g_thread_count;
   gpr_mu_unlock(&g_mu);
-  gpr_log(GPR_DEBUG, "Spawn timer thread");
+  if (GRPC_TRACER_ON(grpc_timer_check_trace)) {
+    gpr_log(GPR_DEBUG, "Spawn timer thread");
+  }
   gpr_thd_id thd;
   gpr_thd_options opt = gpr_thd_options_default();
   gpr_thd_options_set_joinable(&opt);
@@ -122,7 +128,9 @@ static void timer_thread(void *unused) {
         // if there's no thread waiting with a timeout, kick an existing waiter
         // so that the next deadline is not missed
         if (!g_has_timed_waiter) {
-          gpr_log(GPR_DEBUG, "kick untimed waiter");
+          if (GRPC_TRACER_ON(grpc_timer_check_trace)) {
+            gpr_log(GPR_DEBUG, "kick untimed waiter");
+          }
           gpr_cv_signal(&g_cv_wait);
         }
         gpr_mu_unlock(&g_mu);
@@ -149,15 +157,21 @@ static void timer_thread(void *unused) {
         // cancel an existing one quickly (and when it actually times out it'll
         // figure stuff out instead of incurring a wakeup)
         my_timed_waiter_generation = ++g_timed_waiter_generation;
-        gpr_log(GPR_DEBUG, "sleep for a while");
+        if (GRPC_TRACER_ON(grpc_timer_check_trace)) {
+          gpr_log(GPR_DEBUG, "sleep for a while");
+        }
       } else {
         next = inf_future;
-        gpr_log(GPR_DEBUG, "sleep until kicked");
+        if (GRPC_TRACER_ON(grpc_timer_check_trace)) {
+          gpr_log(GPR_DEBUG, "sleep until kicked");
+        }
       }
       gpr_cv_wait(&g_cv_wait, &g_mu, next);
-      gpr_log(GPR_DEBUG, "wait ended: was_timed:%d kicked:%d",
-              my_timed_waiter_generation == g_timed_waiter_generation,
-              g_kicked);
+      if (GRPC_TRACER_ON(grpc_timer_check_trace)) {
+        gpr_log(GPR_DEBUG, "wait ended: was_timed:%d kicked:%d",
+                my_timed_waiter_generation == g_timed_waiter_generation,
+                g_kicked);
+      }
       // if this was the timed waiter, then we need to check timers, and flag
       // that there's now no timed waiter... we'll look for a replacement if
       // there's work to do after checking timers (code above)
@@ -170,8 +184,8 @@ static void timer_thread(void *unused) {
         grpc_timer_consume_kick();
         g_kicked = false;
       }
+      gpr_mu_unlock(&g_mu);
     }
-    gpr_mu_unlock(&g_mu);
   }
   // terminate the thread: drop the waiter count, thread count, and let whomever
   // stopped the threading stuff know that we're done
@@ -186,7 +200,9 @@ static void timer_thread(void *unused) {
   g_completed_threads = ct;
   gpr_mu_unlock(&g_mu);
   grpc_exec_ctx_finish(&exec_ctx);
-  gpr_log(GPR_DEBUG, "End timer thread");
+  if (GRPC_TRACER_ON(grpc_timer_check_trace)) {
+    gpr_log(GPR_DEBUG, "End timer thread");
+  }
 }
 
 static void start_threads(void) {
@@ -214,11 +230,20 @@ void grpc_timer_manager_init(void) {
 
 static void stop_threads(void) {
   gpr_mu_lock(&g_mu);
+  if (GRPC_TRACER_ON(grpc_timer_check_trace)) {
+    gpr_log(GPR_DEBUG, "stop timer threads: threaded=%d", g_threaded);
+  }
   if (g_threaded) {
     g_threaded = false;
     gpr_cv_broadcast(&g_cv_wait);
+    if (GRPC_TRACER_ON(grpc_timer_check_trace)) {
+      gpr_log(GPR_DEBUG, "num timer threads: %d", g_thread_count);
+    }
     while (g_thread_count > 0) {
       gpr_cv_wait(&g_cv_shutdown, &g_mu, gpr_inf_future(GPR_CLOCK_REALTIME));
+      if (GRPC_TRACER_ON(grpc_timer_check_trace)) {
+        gpr_log(GPR_DEBUG, "num timer threads: %d", g_thread_count);
+      }
       gc_completed_threads();
     }
   }