From 51d0ff0f3da604dceac413b892e349ffd78f9237 Mon Sep 17 00:00:00 2001
From: David Garcia Quintas <dgq@google.com>
Date: Mon, 10 Jul 2017 00:46:22 -0700
Subject: [PATCH] Fix deadlocks in grpclb_end2end_test

---
 test/cpp/end2end/grpclb_end2end_test.cc | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/test/cpp/end2end/grpclb_end2end_test.cc b/test/cpp/end2end/grpclb_end2end_test.cc
index 4f839f77883..74ded73ea63 100644
--- a/test/cpp/end2end/grpclb_end2end_test.cc
+++ b/test/cpp/end2end/grpclb_end2end_test.cc
@@ -194,12 +194,13 @@ class BalancerServiceImpl : public BalancerService {
     for (const auto& response_and_delay : responses_and_delays) {
       {
         std::unique_lock<std::mutex> lock(mu_);
-        if (shutdown_) break;
+        if (shutdown_) goto done;
       }
       SendResponse(stream, response_and_delay.first, response_and_delay.second);
     }
     {
       std::unique_lock<std::mutex> lock(mu_);
+      if (shutdown_) goto done;
       serverlist_cond_.wait(lock);
     }
 
@@ -209,6 +210,9 @@ class BalancerServiceImpl : public BalancerService {
       gpr_log(GPR_INFO, "LB: recv client load report msg: '%s'",
               request.DebugString().c_str());
       GPR_ASSERT(request.has_client_stats());
+      // We need to acquire the lock here in order to prevent the notify_one
+      // below from firing before its corresponding wait is executed.
+      std::lock_guard<std::mutex> lock(mu_);
       client_stats_.num_calls_started +=
           request.client_stats().num_calls_started();
       client_stats_.num_calls_finished +=
@@ -224,10 +228,9 @@ class BalancerServiceImpl : public BalancerService {
               .num_calls_finished_with_client_failed_to_send();
       client_stats_.num_calls_finished_known_received +=
           request.client_stats().num_calls_finished_known_received();
-      std::lock_guard<std::mutex> lock(mu_);
       load_report_cond_.notify_one();
     }
-
+  done:
     gpr_log(GPR_INFO, "LB: done");
     return Status::OK;
   }
@@ -428,19 +431,24 @@ class GrpclbEnd2endTest : public ::testing::Test {
     explicit ServerThread(const grpc::string& type,
                           const grpc::string& server_host, T* service)
         : type_(type), service_(service) {
+      std::mutex mu;
+      // We need to acquire the lock here in order to prevent the notify_one
+      // by ServerThread::Start from firing before the wait below is hit.
+      std::unique_lock<std::mutex> lock(mu);
       port_ = grpc_pick_unused_port_or_die();
       gpr_log(GPR_INFO, "starting %s server on port %d", type_.c_str(), port_);
-      std::mutex mu;
       std::condition_variable cond;
       thread_.reset(new std::thread(
           std::bind(&ServerThread::Start, this, server_host, &mu, &cond)));
-      std::unique_lock<std::mutex> lock(mu);
       cond.wait(lock);
       gpr_log(GPR_INFO, "%s server startup complete", type_.c_str());
     }
 
     void Start(const grpc::string& server_host, std::mutex* mu,
                std::condition_variable* cond) {
+      // We need to acquire the lock here in order to prevent the notify_one
+      // below from firing before its corresponding wait is executed.
+      std::lock_guard<std::mutex> lock(*mu);
       std::ostringstream server_address;
       server_address << server_host << ":" << port_;
       ServerBuilder builder;
@@ -448,13 +456,12 @@ class GrpclbEnd2endTest : public ::testing::Test {
                                InsecureServerCredentials());
       builder.RegisterService(service_);
       server_ = builder.BuildAndStart();
-      std::lock_guard<std::mutex> lock(*mu);
       cond->notify_one();
     }
 
     void Shutdown() {
       gpr_log(GPR_INFO, "%s about to shutdown", type_.c_str());
-      server_->Shutdown();
+      server_->Shutdown(grpc_timeout_milliseconds_to_deadline(0));
       thread_->join();
       gpr_log(GPR_INFO, "%s shutdown completed", type_.c_str());
     }
@@ -820,6 +827,7 @@ TEST_F(UpdatesTest, UpdateBalancersDeadUpdate) {
 
   // Kill balancer 0
   gpr_log(GPR_INFO, "********** ABOUT TO KILL BALANCER 0 *************");
+  balancers_[0]->NotifyDoneWithServerlists();
   if (balancers_[0]->Shutdown()) balancer_servers_[0].Shutdown();
   gpr_log(GPR_INFO, "********** KILLED BALANCER 0 *************");