zmq hangs issue. a tricky solution

Multiverso.sln

@@ -10,6 +10,8 @@ Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Test", "Test\Test.vcxproj",
 EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Multiverso", "src\Multiverso.vcxproj", "{16F14058-B116-49D9-8BA0-209F3AFFE849}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "app", "app", "{E89A2FAD-9A40-49CD-89C1-519721658DF0}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		debug_zmq|x64 = debug_zmq|x64

include/multiverso/net/zmq_net.h

@@ -29,11 +29,10 @@ public:
     // get machine file 
     if (active_) return;
     // CHECK(*argc > 2);
-    std::vector<std::string> machine_lists;
+    ParseMachineFile(MV_CONFIG_machine_file, &machine_lists_);
-    ParseMachineFile(MV_CONFIG_machine_file, &machine_lists);
     int port = MV_CONFIG_port; // atoi(argv[2]);
 
-    size_ = static_cast<int>(machine_lists.size());
+    size_ = static_cast<int>(machine_lists_.size());
     CHECK(size_ > 0);
     std::unordered_set<std::string> local_ip;
     net::GetLocalIPAddress(&local_ip);
@@ -41,7 +40,7 @@ public:
     context_ = zmq_ctx_new();
     zmq_ctx_set(context_, ZMQ_MAX_SOCKETS, 256);
 
-    for (auto ip : machine_lists) {
+    for (auto ip : machine_lists_) {
       if (local_ip.find(ip) != local_ip.end()) { // my rank
         rank_ = static_cast<int>(senders_.size());
         senders_.push_back(nullptr);
@@ -49,12 +48,16 @@ public:
         int rc = zmq_bind(receiver_, 
           ("tcp://" + ip + ":" + std::to_string(port)).c_str());
         CHECK(rc == 0);
+        int linger = 0;
+        CHECK(zmq_setsockopt(receiver_, ZMQ_LINGER, &linger, sizeof(linger)) == 0);
       } else {
-        void* senders = zmq_socket(context_, ZMQ_DEALER);
+        void* sender = zmq_socket(context_, ZMQ_DEALER);
-        int rc = zmq_connect(senders, 
+        int rc = zmq_connect(sender, 
           ("tcp://" + ip + ":" + std::to_string(port)).c_str());
         CHECK(rc == 0);
-        senders_.push_back(senders);
+        senders_.push_back(sender);
+        int linger = 0;
+        CHECK(zmq_setsockopt(sender, ZMQ_LINGER, &linger, sizeof(linger)) == 0);
       }
     }
     CHECK_NOTNULL(receiver_);
@@ -71,6 +74,8 @@ public:
     receiver_ = zmq_socket(context_, ZMQ_DEALER);
     int rc = zmq_bind(receiver_, ("tcp://" + ip_port).c_str());
     if (rc == 0) {
+      int linger = 0;
+      CHECK(zmq_setsockopt(receiver_, ZMQ_LINGER, &linger, sizeof(linger)) == 0);
       return 0;
     }
     else {
@@ -91,6 +96,7 @@ public:
       if (rank == rank_) continue;
       std::string ip_port(endpoints[i]);
       senders_[rank] = zmq_socket(context_, ZMQ_DEALER);
+      // NOTE(feiga): set linger to 0, otherwise will hang
       int rc = zmq_connect(senders_[rank], ("tcp://" + ip_port).c_str());
       if (rc != 0) {
         Log::Error("Failed to connect the socket for sender, rank = %d, " 
@@ -104,10 +110,22 @@ public:
 
   void Finalize() override {
     active_ = false;
-    // zmq_term(context_);
+    for (int i = 0; i < senders_.size(); ++i) {
-    zmq_close(receiver_);
+      if (i != rank_) {
-    for (auto& p : senders_) if (p) zmq_close(p);
+        int linger = 0;
-    zmq_ctx_destroy(context_);
+        CHECK(zmq_setsockopt(senders_[i], ZMQ_LINGER, &linger, sizeof(linger)) == 0);
+        int rc = zmq_close(senders_[i]);
+        CHECK(rc == 0);
+      }
+    }
+    int linger = 0;
+    CHECK(zmq_setsockopt(receiver_, ZMQ_LINGER, &linger, sizeof(linger)) == 0);
+    int rc = zmq_close(receiver_);
+    CHECK(rc == 0);
+
+    CHECK(zmq_ctx_shutdown(context_)==0);
+    // zmq_ctx_term(context_);
+    Log::Info("zmq finalize: close context\n");
   }
 
   bool active() const override { return active_; }
@@ -151,7 +169,7 @@ public:
     MessagePtr& msg = *msg_ptr;
     msg->data().clear();
     CHECK(msg.get());
-    recv_size = zmq_recv(receiver_, msg->header(), Message::kHeaderSize, 0);
+    recv_size = zmq_recv(receiver_, msg->header(), Message::kHeaderSize, ZMQ_DONTWAIT);
     if (recv_size < 0) { return -1; }
     CHECK(Message::kHeaderSize == recv_size);
 
@@ -236,6 +254,7 @@ protected:
   std::vector<void*> senders_;
   int rank_;
   int size_;
+  std::vector<std::string> machine_lists_;
 };
 } // namespace multiverso
 

src/communicator.cpp

@@ -33,7 +33,7 @@ Communicator::Communicator() : Actor(actor::kCommunicator) {
 }
 
 Communicator::~Communicator() {
-
+  recv_thread_->join();
 }
 
 void Communicator::Main() {
@@ -78,8 +78,9 @@ void Communicator::Communicate() {
     MessagePtr msg(new Message());
     size_t size = net_util_->Recv(&msg);
     if (size == -1) {
-      Log::Debug("recv return -1\n");
+      continue;
-      break;
+      // Log::Debug("recv return -1\n");
+      // break;
     }
     if (size > 0) {
       // a message received

src/zoo.cpp

@@ -50,6 +50,8 @@ void Zoo::Stop(bool finalize_net) {
   if (!MV_CONFIG_ma) { StopPS(); }
   // Stop the network
   if (finalize_net) net_util_->Finalize();
+  for (auto actor : zoo_) delete actor.second;
+  Log::Info("Multiverso Shutdown successfully\n");
 }
 
 int Zoo::rank() const { return NetInterface::Get()->rank(); }