1 files changed, 17 insertions, 11 deletions

diff --git a/src/ruby/ext/grpc/rb_server.c b/src/ruby/ext/grpc/rb_server.c
index 2a6a246e67..c7b112c94b 100644
--- a/src/ruby/ext/grpc/rb_server.c
+++ b/src/ruby/ext/grpc/rb_server.c
@@ -37,6 +37,7 @@
 #include "rb_server.h"
 
 #include <grpc/grpc.h>
+#include <grpc/support/atm.h>
 #include <grpc/grpc_security.h>
 #include <grpc/support/log.h>
 #include "rb_call.h"
@@ -59,22 +60,26 @@ typedef struct grpc_rb_server {
   /* The actual server */
   grpc_server *wrapped;
   grpc_completion_queue *queue;
+  gpr_atm shutdown_started;
 } grpc_rb_server;
 
 static void destroy_server(grpc_rb_server *server, gpr_timespec deadline) {
   grpc_event ev;
-  if (server->wrapped != NULL) {
-    grpc_server_shutdown_and_notify(server->wrapped, server->queue, NULL);
-    ev = rb_completion_queue_pluck(server->queue, NULL, deadline, NULL);
-    if (ev.type == GRPC_QUEUE_TIMEOUT) {
-      grpc_server_cancel_all_calls(server->wrapped);
-      rb_completion_queue_pluck(server->queue, NULL,
-                                gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
+  // This can be started by app or implicitly by GC. Avoid a race between these.
+  if (gpr_atm_full_fetch_add(&server->shutdown_started, (gpr_atm)1) == 0) {
+    if (server->wrapped != NULL) {
+      grpc_server_shutdown_and_notify(server->wrapped, server->queue, NULL);
+      ev = rb_completion_queue_pluck(server->queue, NULL, deadline, NULL);
+      if (ev.type == GRPC_QUEUE_TIMEOUT) {
+        grpc_server_cancel_all_calls(server->wrapped);
+        rb_completion_queue_pluck(server->queue, NULL,
+                                  gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
+      }
+      grpc_server_destroy(server->wrapped);
+      grpc_rb_completion_queue_destroy(server->queue);
+      server->wrapped = NULL;
+      server->queue = NULL;
     }
-    grpc_server_destroy(server->wrapped);
-    grpc_rb_completion_queue_destroy(server->queue);
-    server->wrapped = NULL;
-    server->queue = NULL;
   }
 }
 
@@ -115,6 +120,7 @@ static const rb_data_type_t grpc_rb_server_data_type = {
 static VALUE grpc_rb_server_alloc(VALUE cls) {
   grpc_rb_server *wrapper = ALLOC(grpc_rb_server);
   wrapper->wrapped = NULL;
+  wrapper->shutdown_started = (gpr_atm)0;
   return TypedData_Wrap_Struct(cls, &grpc_rb_server_data_type, wrapper);
 }