diff --git a/oneflow/core/comm_network/epoll/io_event_poller.cpp b/oneflow/core/comm_network/epoll/io_event_poller.cpp
index 020d6c0f8bdbb146ef85199d318a5922d00fd98f..c71add53c9bc19e5863a6ae2033a1cefbd39ede6 100644
--- a/oneflow/core/comm_network/epoll/io_event_poller.cpp
+++ b/oneflow/core/comm_network/epoll/io_event_poller.cpp
@@ -25,28 +25,44 @@ IOEventPoller::~IOEventPoller() {
 
 void IOEventPoller::AddFd(int fd, std::function<void()> read_handler,
                           std::function<void()> write_handler) {
+  AddFd(fd, &read_handler, &write_handler);
+}
+
+void IOEventPoller::AddFdWithOnlyReadHandler(
+    int fd, std::function<void()> read_handler) {
+  AddFd(fd, &read_handler, nullptr);
+}
+
+void IOEventPoller::Start() {
+  thread_ = std::thread(&IOEventPoller::EpollLoop, this);
+}
+
+void IOEventPoller::AddFd(int fd, std::function<void()>* read_handler,
+                          std::function<void()>* write_handler) {
   unclosed_fd_cnt_ += 1;
   fds_.push_back(fd);
   // Set Fd NONBLOCK
   int opt = fcntl(fd, F_GETFL);
   PCHECK(opt != -1);
   PCHECK(fcntl(fd, F_SETFL, opt | O_NONBLOCK) == 0);
+  // Set CLOEXEC
+  opt = fcntl(fd, F_GETFD);
+  PCHECK(opt != -1);
+  PCHECK(fcntl(fd, F_SETFD, opt | FD_CLOEXEC) == 0);
   // New IOHandler on Heap
   IOHandler* io_handler = new IOHandler;
-  io_handler->read_handler = read_handler;
-  io_handler->write_handler = write_handler;
+  if (read_handler) { io_handler->read_handler = *read_handler; }
+  if (write_handler) { io_handler->write_handler = *write_handler; }
   io_handlers_.push_front(io_handler);
   // Add Fd to Epoll
   epoll_event ep_event;
-  ep_event.events = EPOLLIN | EPOLLOUT | EPOLLET;
+  ep_event.events = EPOLLET;
+  if (read_handler) { ep_event.events |= EPOLLIN; }
+  if (write_handler) { ep_event.events |= EPOLLOUT; }
   ep_event.data.ptr = io_handler;
   PCHECK(epoll_ctl(epfd_, EPOLL_CTL_ADD, fd, &ep_event) == 0);
 }
 
-void IOEventPoller::Start() {
-  thread_ = std::thread(&IOEventPoller::EpollLoop, this);
-}
-
 void IOEventPoller::EpollLoop() {
   while (unclosed_fd_cnt_ > 0) {
     int event_num = epoll_wait(epfd_, ep_events_, max_event_num_, -1);
diff --git a/oneflow/core/comm_network/epoll/io_event_poller.h b/oneflow/core/comm_network/epoll/io_event_poller.h
index 6a56bd16c666872f7976efc5b9db29f6169d01f6..08b9822c4e15200086e604d7d0a2975c3394489f 100644
--- a/oneflow/core/comm_network/epoll/io_event_poller.h
+++ b/oneflow/core/comm_network/epoll/io_event_poller.h
@@ -15,15 +15,23 @@ class IOEventPoller final {
 
   void AddFd(int fd, std::function<void()> read_handler,
              std::function<void()> write_handler);
+  void AddFdWithOnlyReadHandler(int fd, std::function<void()> read_handler);
 
   void Start();
 
  private:
   struct IOHandler {
+    IOHandler() {
+      read_handler = []() { UNEXPECTED_RUN(); };
+      write_handler = []() { UNEXPECTED_RUN(); };
+    }
     std::function<void()> read_handler;
     std::function<void()> write_handler;
   };
 
+  void AddFd(int fd, std::function<void()>* read_handler,
+             std::function<void()>* write_handler);
+
   void EpollLoop();
   static const int max_event_num_;
 
diff --git a/oneflow/core/comm_network/epoll/socket_read_helper.cpp b/oneflow/core/comm_network/epoll/socket_read_helper.cpp
index 8298716e835e0cbd17a54508a9f2330d0c9d3ea0..f012afb9ff1485bd0a9c74fd15bf15440eb4901e 100644
--- a/oneflow/core/comm_network/epoll/socket_read_helper.cpp
+++ b/oneflow/core/comm_network/epoll/socket_read_helper.cpp
@@ -57,7 +57,7 @@ bool SocketReadHelper::DoCurRead(
 void SocketReadHelper::SetStatusWhenMsgHeadDone() {
   switch (cur_msg_.msg_type) {
 #define MAKE_ENTRY(x, y) \
-  case SocketMsgType::k##x: SetStatusWhen##x##MsgHeadDone();
+  case SocketMsgType::k##x: SetStatusWhen##x##MsgHeadDone(); break;
     OF_PP_FOR_EACH_TUPLE(MAKE_ENTRY, SOCKET_MSG_TYPE_SEQ);
 #undef MAKE_ENTRY
     default: UNEXPECTED_RUN();
diff --git a/oneflow/core/comm_network/epoll/socket_write_helper.cpp b/oneflow/core/comm_network/epoll/socket_write_helper.cpp
index 065cf87f88fecc24aabea224384e084543b2008f..7749640e3f1c310c93ef048c55ea7533170e0f98 100644
--- a/oneflow/core/comm_network/epoll/socket_write_helper.cpp
+++ b/oneflow/core/comm_network/epoll/socket_write_helper.cpp
@@ -21,12 +21,9 @@ SocketWriteHelper::SocketWriteHelper(int sockfd, IOEventPoller* poller) {
   sockfd_ = sockfd;
   queue_not_empty_fd_ = eventfd(0, 0);
   PCHECK(queue_not_empty_fd_ != -1);
-  poller->AddFd(queue_not_empty_fd_,
-                std::bind(&SocketWriteHelper::ProcessQueueNotEmptyEvent, this),
-                [this]() {
-                  // TODO: delete this log
-                  LOG(INFO) << "fd " << queue_not_empty_fd_ << " writeable";
-                });
+  poller->AddFdWithOnlyReadHandler(
+      queue_not_empty_fd_,
+      std::bind(&SocketWriteHelper::ProcessQueueNotEmptyEvent, this));
   cur_msg_queue_ = new std::queue<SocketMsg>;
   pending_msg_queue_ = new std::queue<SocketMsg>;
   cur_write_handle_ = &SocketWriteHelper::InitMsgWriteHandle;