Opening multiple UNIX domain sockets in Node.js: Why do I get EAGAIN errors?

My use case (webservice):

Multiple clients => Webserver => Message to C program through UNIX domain socket.

I've been using Apache + PHP for the webserver layer, but I'm currently in the process of replacing it with Node.js.

The webservice gets up to 100 requests/sec, so it's a very real scenario that the C program will be busy when a new request comes in. PHP handles this just fine, but Node.js often fails with the error:

{
  "code": "EAGAIN",
  "errno": "EAGAIN",
  "syscall": "connect",
  "address": "/tmp/service.sock"
}

I'm assuming this is because PHP performs some kind of message queue/retry that will ensure all messages are sent to the C program (which Node.js does not).

Is there a simple way to do the same in Node.js or will have I have to implement a custom message queue?

C socket creation:

int listenSocket, newSocket;
struct sockaddr_un localAddress, remoteAddress;

// Create socket
if ((listenSocket = socket(AF_UNIX, SOCK_STREAM, 0)) == -1){
  printf("Error opening listener socket");
  exit(1);
}

// Configure socket
localAddress.sun_family = AF_UNIX; // Set UNIX domain socket type
strcpy(localAddress.sun_path, "/tmp/service.sock");
unlink(localAddress.sun_path); // Remove any previous instances of the socket

// Open listener socket
int len = strlen(localAddress.sun_path) + sizeof(localAddress.sun_family);
if (bind(listenSocket, (struct sockaddr *)&localAddress, len) == -1){
  printf("Error binding socket at %s", localAddress.sun_path);
  exit(1);
}
chmod(localAddress.sun_path, 0777);

// Listen for new connections on the listener socket
if (listen(listenSocket, 5) == -1){
  printf("Error listening on listener socket");
  exit(1);
}

// Handle new connections
while(!shutdown){
  printf("Waiting for a connection...\n");

  // Accept new connection
  int sizeofRemoteAddress = sizeof(remoteAddress);
  if ((newSocket = accept(listenSocket, (struct sockaddr *)&remoteAddress, &sizeofRemoteAddress)) == -1){
    printf("Error accepting new connection: %s\n", strerror(errno));
    continue;
  }

  // Read and handle data from client...
}

Connecting to the socket in PHP:

$socket = @socket_create(AF_UNIX, SOCK_STREAM, 0);
if (!$socket) return false;

$connected = @socket_connect($socket, "/tmp/service.sock");
if (!$connected) return false;

// Send message to server and read response...

Connecting to the socket in Node.js:

new Promise(function(resolve, reject){
  var socket = Net.connect("/tmp/service.sock");

  socket.on("error", function(err){
    reject(err);
  });

  socket.on("connect", function(){
    socket.write(message);
  });

  socket.on("data", function(data){
    socket.end();
    resolve(data.toString("UTF-8"));
  });
});