perf(conn): move slave connector write to separate thread to allow wr…

…iting to multiple slaves in parallel

src/main/java/org/arl/fjage/remote/ConnectionHandler.java

@@ -38,6 +38,8 @@ class ConnectionHandler extends Thread {
   private Logger log = Logger.getLogger(getClass().getName());
   private RemoteContainer container;
   private boolean alive, keepAlive;
+  private ExecutorService pool = Executors.newSingleThreadExecutor();
+
 
   public ConnectionHandler(Connector conn, RemoteContainer container) {
     this.conn = conn;
@@ -49,7 +51,6 @@ public ConnectionHandler(Connector conn, RemoteContainer container) {
 
   @Override
   public void run() {
-    ExecutorService pool = Executors.newSingleThreadExecutor();
     BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
     out = new DataOutputStream(conn.getOutputStream());
     if (keepAlive) println(ALIVE);
@@ -149,6 +150,10 @@ synchronized void println(String s) {
     }
   }
 
+  void printlnQueued(String s) {
+    if (pool != null) pool.execute(() -> println(s));
+  }
+
   JsonMessage printlnAndGetResponse(String s, String id, long timeout) {
     if (conn == null) return null;
     if (keepAlive && !alive && container instanceof MasterContainer) return null;

src/main/java/org/arl/fjage/remote/MasterContainer.java

@@ -211,7 +211,7 @@ public boolean send(Message m, boolean relay) {
     if (needsCleanup) cleanupSlaves();
     synchronized(slaves) {
       for (ConnectionHandler slave: slaves)
-        slave.println(json);
+        slave.printlnQueued(json);
     }
     return true;
   }