Add tiles-rendered-at-once setting, control update tile concurrency

src/main/java/org/dynmap/AsynchronousQueue.java

@@ -23,6 +23,7 @@ public class AsynchronousQueue<T> {
         this.dequeueTime = dequeueTime;
         this.accelDequeueTime = accelDequeueTime;
         this.accelDequeueThresh = accelDequeueThresh;
+        if(pendinglimit < 1) pendinglimit = 1;
         this.pendinglimit = pendinglimit;
     }
 

src/main/java/org/dynmap/MapManager.java

@@ -683,7 +683,8 @@ public class MapManager {
             }, 
             (int) (configuration.getDouble("renderinterval", 0.5) * 1000),
             configuration.getInteger("renderacceleratethreshold", 30),
-            (int)(configuration.getDouble("renderaccelerateinterval", 0.2) * 1000), (Runtime.getRuntime().availableProcessors()+1)/2);
+            (int)(configuration.getDouble("renderaccelerateinterval", 0.2) * 1000), 
+            configuration.getInteger("tiles-rendered-at-once", (Runtime.getRuntime().availableProcessors()+1)/2));
 
         /* On dedicated thread, so default to no delays */
         timeslice_int = (long)(configuration.getDouble("timesliceinterval", 0.0) * 1000);

src/main/resources/configuration.txt

@@ -130,6 +130,9 @@ renderacceleratethreshold: 60
 # How often to render tiles when backlog is above renderacceleratethreshold
 renderaccelerateinterval: 0.2
 
+# How many update tiles to work on at once (if not defined, default is 1/2 the number of cores)
+tiles-rendered-at-once: 2
+
 # Save and restore pending tile renders - prevents their loss on server shutdown or /reload
 saverestorepending: true