Q: Performance warning

[angelskieglazki]

Hello!
Are these messages normal? It seems to me that I am doing something wrong.

...
  0.000000 Waited 2.2ms for SteamNetworkingSockets lock
  0.000000 SteamNetworkingSockets lock held for 6.4ms.  (Performance warning.)  ServiceThread,CSteamNetworkConnectionBase::Think(x2),SNP_SendPacket(x2),SendUDPacket(x2)
This is usually a symptom of a general performance problem such as thread starvation.
  0.000000 SteamNetworkingSockets lock held for 6.8ms.  (Performance warning.)  ServiceThread,RecvUDPPacket,CSteamNetworkConnectionBase::Think,SNP_SendPacket,SendUDPacket
This is usually a symptom of a general performance problem such as thread starvation.
  0.000000 Waited 3.7ms for SteamNetworkingSockets lock
  0.000000 Waited 2.4ms for SteamNetworkingSockets lock
  ...
  0.000000 SteamNetworkingSockets lock held for 5.7ms.  (Performance warning.)  ServiceThread,CSteamNetworkConnectionBase::Think(x9),SNP_SendPacket(x18),SendUDPacket(x18)
This is usually a symptom of a general performance problem such as thread starvation
  0.000000 SteamNetworkingSockets lock held for 8.8ms.  (Performance warning.)  ServiceThread
This is usually a symptom of a general performance problem such as thread starvation.
  0.000000 SteamNetworkingSockets lock held for 9.1ms.  (Performance warning.)  SendMessages
This is usually a symptom of a general performance problem such as thread starvation.
  0.000000 SteamNetworkingSockets lock held for 32.5ms.  (Performance warning.)  ServiceThread,CSteamNetworkConnectionBase::Think(x8),SNP_SendPacket(x8),SendUDPacket(x8)
This is usually a symptom of a general performance problem such as thread starvation.
  0.000000 SteamNetworkingSockets lock held for 32.9ms.  (Performance warning.)  SendMessages
This is usually a symptom of a general performance problem such as thread starvation.
  0.000000 SteamNetworkingSockets lock held for 20.7ms.  (Performance warning.)  ServiceThread
This is usually a symptom of a general performance problem such as thread starvation.
  0.000000 SteamNetworkingSockets lock held for 20.8ms.  (Performance warning.)  SendMessages
This is usually a symptom of a general performance problem such as thread starvation
...

I’ll describe a little how my game server works, there are two threads from which the GNS api is called.

1. Server network thread.

void server_network_thread() {
  while (Is_running_) {
    auto till = clock->nowMilliseconds() + THREAD_SLEEP_DELAY;
    processIncomingMessages();
    pollConnectionStateChanges();
    sendMessages(0);
    std::this_thread::sleep_until(till);
  }
}

 processIncomingMessages(); - contains reading messages one by one using the function ReceiveMessagesOnPollGroup(...);
 pollConnectionStateChanges(); - calling SteamNetworkingSockets()->RunCallbacks();
 sendMessages(0); - generates messages from the send queue and sends them through the function SteamNetworkingSockets()->SendMessages(...);
 THREAD_SLEEP_DELAY = 1ms or 5ms, does not affect the final result

so this thread is running and then we will get a message about creating a game room:

2. Room thread - a little more complicated, typical game loop:

class RoomTicker {
public:
  RoomTicker() = default;
  ~RoomTicker() = default;
  void inc() { ++currentTick_; }
  int64_t currentTick() const { return currentTick_;}
  int64_t currentTickTime() const { return (int64_t)((double)(currentTick_ * 1000) / TICKS_PER_SECOND); }
  static constexpr float deltaTime() { return 1000. / TICKS_PER_SECOND; }
  static constexpr double TICKS_PER_SECOND = 40.;
private:
  int64_t currentTick_ = 0;
};

void gameroom_thread() {
  room_start_time = clock->nowMilliseconds();

  while (Is_running_) {
    int64_t room_time = clock->nowMilliseconds() - room_start_time;
    readAllMessages();
    processAllMessages();

    int passed_ticks = 0;
    for (; ticker.currentTickTime() <= room_time; ticker.inc()) {
      ++passed_ticks;
      {
        // SOME GAME LOGIC
        // SOME GAME LOGIC
        // SOME GAME LOGIC
      }
      sendMessages(ticker_.currentTick());
    }

    if (passed_ticks <= 1) {
      const auto till = std::chrono::time_point<std::chrono::system_clock>(
                std::chrono::milliseconds(room_start_time + ticker.currentTickTime()));
      std::this_thread::sleep_until(till);
    }
  }
}

readAllMessages(); - here I read as many messages from the socket as I can. I set the constant to 200 messages. I read the messages, put them in a recvQueue, and so on until SteamNetworkingSockets()->ReceiveMessagesOnPollGroup(roomPollGroup, messages_array, 200); will not return 0.
processAllMessages - process all commands and messages that were received
// SOME GAME LOGIC - game logic. We create messages and fill the sending queue.
sendMessages(ticker_.currentTick()); -  send all messages from sendQueue via  SteamNetworkingSockets()->SendMessages(...);

Сlients send reliable messages with positions about 50 times per second. Starting from 30+ players, lags begin and warnings begin to spam.
I started thinking and this is what I came up with: if 30 players are connected and they send 50 messages per second, then 1500 times per second I call GNS-api. Since I am not calling it from a network thread, GNS-mutexes will be locked there, which is what I see (0.000000 Waited 2.4ms for SteamNetworkingSockets lock ... and so on).
Perhaps I should send and receive messages in only one network thread, then the thread-contention will be minimal and the wait on the GNS mutexes will also be minimal. And the room threads will communicate with the network thread through queues, which I will somehow exchange under my mutex.

In general, I want to consult with you :)

regards, max