Fix memory leak

.vscode/launch.json

@@ -9,14 +9,14 @@
             "name": "Launch Current File",
             "request": "launch",
             "mainClass": "${file}",
-            "vmArgs": "-Xmx4G -Xms1024m -Djava.library.path=./shared-folder -XX:+UseZGC -XX:SoftMaxHeapSize=3G -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=\"./tmp/heap.dump\""
+            "vmArgs": "-Xmx4G -Xms1024m -Djava.library.path=./shared-folder -XX:+UseZGC -XX:SoftMaxHeapSize=3G -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=\"./tmp/heap.hprof\""
         },
         {
             "type": "java",
             "name": "Launch Main",
             "request": "launch",
             "mainClass": "electrosphere.engine.Main",
-            "vmArgs": "-Xmx4G -Xms1024m -Djava.library.path=./shared-folder -XX:+UseZGC -XX:SoftMaxHeapSize=3G -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=\"./tmp/heap.dump\"",
+            "vmArgs": "-Xmx4G -Xms1024m -Djava.library.path=./shared-folder -XX:+UseZGC -XX:SoftMaxHeapSize=3G -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=\"./tmp/heap.hprof\"",
             "projectName": "Renderer"
         },
         {
@@ -24,7 +24,7 @@
             "name": "Launch Main (Debug Memory)",
             "request": "launch",
             "mainClass": "electrosphere.engine.Main",
-            "vmArgs": "-Xmx4G -Xms1024m -Djava.library.path=./shared-folder -XX:+UseZGC -XX:SoftMaxHeapSize=3G -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=\"./tmp/heap.dump\" -javaagent:./lwjglx-debug-1.0.0.jar=t;o=trace.log",
+            "vmArgs": "-Xmx4G -Xms1024m -Djava.library.path=./shared-folder -XX:+UseZGC -XX:SoftMaxHeapSize=3G -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=\"./tmp/heap.hprof\" -javaagent:./lwjglx-debug-1.0.0.jar=t;o=trace.log",
             "projectName": "Renderer"
         },
         {
@@ -35,7 +35,7 @@
             "env": {
                 "ALSOFT_LOGLEVEL": 4,
             },
-            "vmArgs": "-Xmx4G -Xms1024m -Djava.library.path=./shared-folder -XX:+UseZGC -XX:SoftMaxHeapSize=3G -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=\"./tmp/heap.dump\"",
+            "vmArgs": "-Xmx4G -Xms1024m -Djava.library.path=./shared-folder -XX:+UseZGC -XX:SoftMaxHeapSize=3G -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=\"./tmp/heap.hprof\"",
             "projectName": "Renderer"
         },
         {

docs/src/progress/renderertodo.md

@@ -1206,6 +1206,7 @@ Move header file generation location
 Add more debugging tools for fluids
 Remove conditional update check in fluid sim
 Explicit memory management of fluid chunk cache buffers
+Fix GriddedDataCellManager memory leak caused by physics and ConcurrentHashMap
 
 
 

docs/src/tools/profiling/eclipsememoryanalyzer.md

@@ -0,0 +1,3 @@
+@page eclipsememoryanalyzer Eclipse Memory Analyzer
+
+Useful for viewing memory usage (particularly gives good reports of memory leaks)

docs/src/tools/profiling/visualvm.md

@@ -0,0 +1,3 @@
+@page visualvm VisualVM
+
+Useful for profiling CPU usage

docs/src/tools/toolsindex.md

@@ -6,3 +6,5 @@
  - @subpage indexdocumentation
  - @subpage jenkins
  - @subpage gimp
+ - @subpage visualvm
+ - @subpage eclipsememoryanalyzer

src/main/java/electrosphere/client/block/BlockChunkCache.java

@@ -18,7 +18,7 @@ public class BlockChunkCache {
     /**
      * Number of chunks to cache
      */
-    static final int CACHE_SIZE = 1500;
+    static final int CACHE_SIZE = 500;
 
     /**
      * The size of the cache

src/main/java/electrosphere/entity/types/terrain/BlockChunkEntity.java

@@ -17,12 +17,10 @@ import electrosphere.entity.Entity;
 import electrosphere.entity.EntityCreationUtils;
 import electrosphere.entity.EntityDataStrings;
 import electrosphere.entity.EntityUtils;
-import electrosphere.entity.ServerEntityUtils;
 import electrosphere.entity.types.collision.CollisionObjUtils;
 import electrosphere.logger.LoggerInterface;
 import electrosphere.renderer.meshgen.BlockMeshgen;
 import electrosphere.renderer.meshgen.BlockMeshgen.BlockMeshData;
-import electrosphere.server.datacell.Realm;
 
 /**
  * Generates block chunk entities
@@ -104,30 +102,16 @@ public class BlockChunkEntity {
 
     /**
      * Creates a block chunk entity on the server
-     * @param realm The realm
+     * @param entity The entity to populate
-     * @param position The position of the chunk
      * @param weights The weights for the block chunk
      * @param values The values of each voxel in the chunk
      * @return The block entity
      */
-    public static Entity serverCreateBlockChunkEntity(Realm realm, Vector3d position, BlockMeshData blockChunkData){
+    public static void serverCreateBlockChunkEntity(Entity entity, BlockMeshData blockChunkData){
-        
-        Entity rVal = EntityCreationUtils.createServerEntity(realm, position);
         if(blockChunkData.getVertices().length > 0){
-            PhysicsEntityUtils.serverAttachTriGeomRigidBody(rVal, blockChunkData);
+            PhysicsEntityUtils.serverAttachTriGeomRigidBody(entity, blockChunkData);
-            rVal.putData(EntityDataStrings.TERRAIN_IS_TERRAIN, true);
+            entity.putData(EntityDataStrings.TERRAIN_IS_TERRAIN, true);
         }
-
-
-        //position entity
-        //this needs to be called at the end of this function.
-        //Burried underneath this is function call to initialize a server side entity.
-        //The server initialization logic checks what type of entity this is, if this function is called prior to its type being stored
-        //the server will not be able to synchronize it properly.
-        ServerEntityUtils.initiallyPositionEntity(realm,rVal,position);
-
-
-        return rVal;
     }
 
     /**

src/main/java/electrosphere/entity/types/terrain/TerrainChunk.java

@@ -18,12 +18,10 @@ import electrosphere.entity.Entity;
 import electrosphere.entity.EntityCreationUtils;
 import electrosphere.entity.EntityDataStrings;
 import electrosphere.entity.EntityUtils;
-import electrosphere.entity.ServerEntityUtils;
 import electrosphere.entity.types.collision.CollisionObjUtils;
 import electrosphere.logger.LoggerInterface;
 import electrosphere.renderer.meshgen.TransvoxelModelGeneration;
 import electrosphere.renderer.meshgen.TransvoxelModelGeneration.TransvoxelChunkData;
-import electrosphere.server.datacell.Realm;
 
 /**
  * Utilities for creating terrain chunk entities
@@ -104,38 +102,24 @@ public class TerrainChunk {
 
     /**
      * Creates a terrain chunk entity on the server
-     * @param realm The realm
+     * @param entity The entity to populate
-     * @param position The position of the chunk
      * @param weights The weights for the terrain chunk
      * @param values The values of each voxel in the chunk
-     * @return The terrain entity
      */
-    public static Entity serverCreateTerrainChunkEntity(Realm realm, Vector3d position, float[][][] weights, int[][][] values){
+    public static void serverCreateTerrainChunkEntity(Entity entity, float[][][] weights, int[][][] values){
         
         TransvoxelChunkData chunkData = new TransvoxelChunkData(weights, values, ClientDrawCellManager.FULL_RES_LOD);
         TerrainChunkData data = TransvoxelModelGeneration.generateTerrainChunkData(chunkData);
 
-        Entity rVal = EntityCreationUtils.createServerEntity(realm, position);
         if(data.vertices.length > 0){
-            PhysicsEntityUtils.serverAttachTriGeomRigidBody(rVal, data);
+            PhysicsEntityUtils.serverAttachTriGeomRigidBody(entity, data);
-            rVal.putData(EntityDataStrings.TERRAIN_IS_TERRAIN, true);
+            entity.putData(EntityDataStrings.TERRAIN_IS_TERRAIN, true);
             // ServerEntityUtils.initiallyPositionEntity(realm, rVal, position);
                     // physicsObject = PhysicsUtils.attachTerrainRigidBody(physicsEntity,heightmap,true);
         // Realm realm = Globals.realmManager.getEntityRealm(physicsEntity);
         // realm.getCollisionEngine().registerPhysicsEntity(physicsEntity);
 
         }
-
-
-        //position entity
-        //this needs to be called at the end of this function.
-        //Burried underneath this is function call to initialize a server side entity.
-        //The server initialization logic checks what type of entity this is, if this function is called prior to its type being stored
-        //the server will not be able to synchronize it properly.
-        ServerEntityUtils.initiallyPositionEntity(realm,rVal,position);
-
-
-        return rVal;
     }
 
     /**

src/main/java/electrosphere/server/datacell/GriddedDataCellManager.java

@@ -11,12 +11,15 @@ import java.util.Set;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Semaphore;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.joml.Vector3d;
 import org.joml.Vector3i;
 
+import electrosphere.client.block.BlockChunkData;
 import electrosphere.engine.Globals;
 import electrosphere.entity.Entity;
+import electrosphere.entity.EntityCreationUtils;
 import electrosphere.entity.EntityUtils;
 import electrosphere.entity.ServerEntityUtils;
 import electrosphere.entity.state.server.ServerPlayerViewDirTree;
@@ -85,7 +88,7 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
     /**
      * Loaded cells
      */
-    Semaphore loadedCellsLock = new Semaphore(1);
+    ReentrantLock loadedCellsLock = new ReentrantLock();
 
     /**
      * Parent realm
@@ -172,7 +175,7 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
                     if(this.canCreateCell(x, y, z) && this.shouldContainPlayer(new Vector3i(x,y,z), worldPos, playerSimulationRadius)){
                         Vector3i targetPos = new Vector3i(x,y,z);
                         LoggerInterface.loggerEngine.DEBUG("GriddedDataCellManager: Add player to " + x + " " + y + " " + z);
-                        loadedCellsLock.acquireUninterruptibly();
+                        loadedCellsLock.lock();
                         if(groundDataCells.get(getServerDataCellKey(targetPos)) != null){
                             groundDataCells.get(getServerDataCellKey(targetPos)).addPlayer(player);
                         } else {
@@ -184,7 +187,7 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
                             //add player
                             groundDataCells.get(getServerDataCellKey(targetPos)).addPlayer(player);
                         }
-                        loadedCellsLock.release();
+                        loadedCellsLock.unlock();
                     }
                 }
             }
@@ -221,18 +224,18 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
                     if(this.canCreateCell(x, y, z) && this.shouldContainPlayer(new Vector3i(x, y, z), newPosition, playerSimulationRadius)){
                         Vector3i targetPos = new Vector3i(x,y,z);
                         if(groundDataCells.get(getServerDataCellKey(targetPos)) != null){
-                            loadedCellsLock.acquireUninterruptibly();
+                            loadedCellsLock.lock();
                             groundDataCells.get(getServerDataCellKey(targetPos)).addPlayer(player);
-                            loadedCellsLock.release();
+                            loadedCellsLock.unlock();
                         } else {
-                            loadedCellsLock.acquireUninterruptibly();
+                            loadedCellsLock.lock();
                             //create data cell
                             createServerDataCell(targetPos);
                             //add to loaded cells
                             cellPlayerlessFrameMap.put(groundDataCells.get(getServerDataCellKey(targetPos)),0);
                             //add player
                             groundDataCells.get(getServerDataCellKey(targetPos)).addPlayer(player);
-                            loadedCellsLock.release();
+                            loadedCellsLock.unlock();
                         }
                     }
                 }
@@ -290,13 +293,32 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
         Long key = this.getServerDataCellKey(worldPos);
         if(posPhysicsMap.containsKey(key)){
             PhysicsDataCell cell = posPhysicsMap.get(key);
-            cell.retireCell();
             cell.generatePhysics();
-        } else {
-            PhysicsDataCell cell = PhysicsDataCell.createPhysicsCell(parent, worldPos);
-            cell.generatePhysics();
-            posPhysicsMap.put(key, cell);
         }
+        //get data to generate with
+        Vector3d realPos = new Vector3d(
+            worldPos.x * ServerTerrainChunk.CHUNK_PLACEMENT_OFFSET,
+            worldPos.y * ServerTerrainChunk.CHUNK_PLACEMENT_OFFSET,
+            worldPos.z * ServerTerrainChunk.CHUNK_PLACEMENT_OFFSET
+        );
+
+        BlockChunkData blockChunkData = parent.getServerWorldData().getServerBlockManager().getChunk(worldPos.x, worldPos.y, worldPos.z);
+        ServerTerrainChunk terrainChunk = parent.getServerWorldData().getServerTerrainManager().getChunk(worldPos.x, worldPos.y, worldPos.z);
+
+        //create entities
+        Entity blockEntity = EntityCreationUtils.createServerEntity(parent, realPos);
+        Entity terrainEntity = EntityCreationUtils.createServerEntity(parent, realPos);
+        
+        //position entity
+        //this needs to be called at the end of this function.
+        //Burried underneath this is function call to initialize a server side entity.
+        //The server initialization logic checks what type of entity this is, if this function is called prior to its type being stored
+        //the server will not be able to synchronize it properly.
+        ServerEntityUtils.initiallyPositionEntity(parent,blockEntity,realPos);
+        ServerEntityUtils.initiallyPositionEntity(parent,terrainEntity,realPos);
+        PhysicsDataCell cell = PhysicsDataCell.createPhysicsCell(worldPos, terrainEntity, blockEntity, terrainChunk, blockChunkData);
+        cell.generatePhysics();
+        posPhysicsMap.put(key, cell);
     }
     
     /**
@@ -318,6 +340,7 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
                 int playerSimulationRadius = player.getSimulationRadius();
 
                 //remove from cells that are out of range
+                loadedCellsLock.lock();
                 for(ServerDataCell cell : this.groundDataCells.values()){
                     Vector3i cellWorldPos = this.getCellWorldPosition(cell);
                     if(cell.containsPlayer(player) && !this.shouldContainPlayer(cellWorldPos, newPosition, playerSimulationRadius)){
@@ -328,6 +351,7 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
                         this.broadcastDestructionToPlayer(player, cell);
                     }
                 }
+                loadedCellsLock.unlock();
 
                 //Add to cells that are in range
                 for(int x = newPosition.x - playerSimulationRadius + 1; x < newPosition.x + playerSimulationRadius; x++){
@@ -336,21 +360,21 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
                             if(this.canCreateCell(x,y,z) && this.shouldContainPlayer(new Vector3i(x,y,z), newPosition, playerSimulationRadius)){
                                 Vector3i targetPos = new Vector3i(x,y,z);
                                 if(groundDataCells.get(this.getServerDataCellKey(targetPos)) != null){
-                                    loadedCellsLock.acquireUninterruptibly();
+                                    loadedCellsLock.lock();
                                     ServerDataCell cell = groundDataCells.get(this.getServerDataCellKey(targetPos));
                                     if(!cell.containsPlayer(player)){
                                         cell.addPlayer(player);
                                     }
-                                    loadedCellsLock.release();
+                                    loadedCellsLock.unlock();
                                 } else {
-                                    loadedCellsLock.acquireUninterruptibly();
+                                    loadedCellsLock.lock();
                                     //create data cell
                                     this.createServerDataCell(targetPos);
                                     //add to loaded cells
                                     cellPlayerlessFrameMap.put(groundDataCells.get(this.getServerDataCellKey(targetPos)),0);
                                     //add player
                                     groundDataCells.get(this.getServerDataCellKey(targetPos)).addPlayer(player);
-                                    loadedCellsLock.release();
+                                    loadedCellsLock.unlock();
                                 }
                             }
                         }
@@ -368,17 +392,19 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
     public void unloadPlayerlessChunks(){
         if(this.unloadCells){
             //TODO: improve to make have less performance impact
-            loadedCellsLock.acquireUninterruptibly();
+            loadedCellsLock.lock();
             for(ServerDataCell cell : this.groundDataCells.values()){
-                if(cell.isReady() && cell.getPlayers().size() < 1){
+                if(cellPlayerlessFrameMap.containsKey(cell)){
-                    int frameCount = cellPlayerlessFrameMap.get(cell) + 1;
+                    if(cell.isReady() && cell.getPlayers().size() < 1){
-                    cellPlayerlessFrameMap.put(cell,frameCount);
+                        int frameCount = cellPlayerlessFrameMap.get(cell) + 1;
-                    if(frameCount > UNLOAD_FRAME_THRESHOLD){
+                        cellPlayerlessFrameMap.put(cell,frameCount);
-                        toCleanQueue.add(cell);
+                        if(frameCount > UNLOAD_FRAME_THRESHOLD){
-                    }
+                            toCleanQueue.add(cell);
-                } else {
+                        }
-                    if(cellPlayerlessFrameMap.get(cell) > 0){
+                    } else {
-                        cellPlayerlessFrameMap.put(cell, 0);
+                        if(cellPlayerlessFrameMap.get(cell) > 0){
+                            cellPlayerlessFrameMap.put(cell, 0);
+                        }
                     }
                 }
             }
@@ -410,6 +436,9 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
                 Vector3i worldPos = getCellWorldPosition(cell);
                 Long key = getServerDataCellKey(worldPos);
                 groundDataCells.remove(key);
+                this.posPhysicsMap.remove(key);
+                this.cellPositionMap.remove(cell);
+                this.cellPlayerlessFrameMap.remove(cell);
                 //offload all entities in cell to chunk file
                 serverContentManager.saveContentToDisk(key, cell.getScene().getEntityList());
                 for(Entity entity : cell.getScene().getEntityList()){
@@ -418,7 +447,7 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
                 //save terrain to disk
                 serverTerrainManager.savePositionToDisk(worldPos);
             }
-            loadedCellsLock.release();
+            loadedCellsLock.unlock();
             toCleanQueue.clear();
         }
     }
@@ -428,7 +457,7 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
      */
     public void evictAll(){
         //TODO: improve to make have less performance impact
-        loadedCellsLock.acquireUninterruptibly();
+        loadedCellsLock.lock();
         for(ServerDataCell cell : this.groundDataCells.values()){
             int frameCount = cellPlayerlessFrameMap.get(cell) + 1;
             cellPlayerlessFrameMap.put(cell,frameCount);
@@ -439,6 +468,9 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
             Vector3i worldPos = getCellWorldPosition(cell);
             Long key = getServerDataCellKey(worldPos);
             groundDataCells.remove(key);
+            this.posPhysicsMap.remove(key);
+            this.cellPositionMap.remove(cell);
+            this.cellPlayerlessFrameMap.remove(cell);
             //offload all entities in cell to chunk file
             serverContentManager.saveContentToDisk(key, cell.getScene().getEntityList());
             //clear all entities in cell
@@ -446,7 +478,7 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
                 ServerEntityUtils.destroyEntity(entity);
             }
         }
-        loadedCellsLock.release();
+        loadedCellsLock.unlock();
         this.serverTerrainManager.evictAll();
         toCleanQueue.clear();
     }
@@ -498,12 +530,12 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
      */
     public ServerDataCell tryCreateCellAtPoint(Vector3i worldPos){
         if(this.canCreateCell(worldPos) && groundDataCells.get(this.getServerDataCellKey(worldPos)) == null){
-            loadedCellsLock.acquireUninterruptibly();
+            loadedCellsLock.lock();
             //create data cell
             this.createServerDataCell(worldPos);
             //add to loaded cells
             cellPlayerlessFrameMap.put(groundDataCells.get(this.getServerDataCellKey(worldPos)),0);
-            loadedCellsLock.release();
+            loadedCellsLock.unlock();
         } else if(groundDataCells.get(this.getServerDataCellKey(worldPos)) == null) {
             LoggerInterface.loggerEngine.WARNING(
                 "Trying to create data cell outside world bounds!\n" +
@@ -532,7 +564,7 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
      */
     public void simulate(){
         Globals.profiler.beginCpuSample("GriddedDataCellManager.simulate");
-        loadedCellsLock.acquireUninterruptibly();
+        loadedCellsLock.lock();
         for(ServerDataCell cell : this.groundDataCells.values()){
             if(Globals.microSimulation != null && Globals.microSimulation.isReady()){
                 Globals.microSimulation.simulate(cell);
@@ -540,19 +572,21 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
 
             //queue fluid simulation
             Vector3i cellPos = this.getCellWorldPosition(cell);
-            this.serverFluidManager.queue(cellPos.x, cellPos.y, cellPos.z);
+            if(cellPos != null){
+                this.serverFluidManager.queue(cellPos.x, cellPos.y, cellPos.z);
+            }
         }
 
         //simulate fluids
-        this.serverFluidManager.simulate();
+        this.serverFluidManager.simulate((ServerFluidChunk fluidChunk) -> {
+            ServerDataCell cell = getCellAtWorldPosition(fluidChunk.getWorldPosition());
+            ServerFluidChunk chunk = getFluidChunkAtPosition(fluidChunk.getWorldPosition());
+            cell.broadcastNetworkMessage(
+                TerrainMessage.constructupdateFluidDataMessage(fluidChunk.getWorldX(), fluidChunk.getWorldY(), fluidChunk.getWorldZ(), TerrainProtocol.constructFluidByteBuffer(chunk).array())
+            );
+        });
 
-        //rebroadcast updated chunks
+        loadedCellsLock.unlock();
-        for(ServerFluidChunk chunk : this.serverFluidManager.getBroadcastQueue()){
-            this.rebroadcastFluidChunk(chunk.getWorldPosition());
-        }
-        this.serverFluidManager.getBroadcastQueue().clear();
-
-        loadedCellsLock.release();
         this.unloadPlayerlessChunks();
         this.updatePlayerPositions();
         Globals.profiler.endCpuSample();
@@ -580,18 +614,55 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
      * Because cell hasn't been registered yet, no simulation is performed until the physics is created.
      * @param worldPos
      */
-    private void runPhysicsGenerationThread(Vector3i worldPos){
+    private static void runPhysicsGenerationThread(
+        Vector3i worldPos,
+        Long key,
+        PhysicsDataCell cell,
+        Map<Long, PhysicsDataCell> posPhysicsMap,
+        Map<Long, ServerDataCell> groundDataCells,
+        Realm realm
+    ){
+        //get data to generate with
+        Vector3d realPos = new Vector3d(
+            worldPos.x * ServerTerrainChunk.CHUNK_PLACEMENT_OFFSET,
+            worldPos.y * ServerTerrainChunk.CHUNK_PLACEMENT_OFFSET,
+            worldPos.z * ServerTerrainChunk.CHUNK_PLACEMENT_OFFSET
+        );
+        BlockChunkData blockChunkData = realm.getServerWorldData().getServerBlockManager().getChunk(worldPos.x, worldPos.y, worldPos.z);
+        ServerTerrainChunk terrainChunk = realm.getServerWorldData().getServerTerrainManager().getChunk(worldPos.x, worldPos.y, worldPos.z);
+        ServerDataCell dataCell = groundDataCells.get(key);
+
+        //create entities
+        Entity blockEntity = EntityCreationUtils.createServerEntity(realm, realPos);
+        Entity terrainEntity = EntityCreationUtils.createServerEntity(realm, realPos);
+        
+        //position entity
+        //this needs to be called at the end of this function.
+        //Burried underneath this is function call to initialize a server side entity.
+        //The server initialization logic checks what type of entity this is, if this function is called prior to its type being stored
+        //the server will not be able to synchronize it properly.
+        ServerEntityUtils.initiallyPositionEntity(realm,blockEntity,realPos);
+        ServerEntityUtils.initiallyPositionEntity(realm,terrainEntity,realPos);
+
+        PhysicsDataCell targetCell = PhysicsDataCell.createPhysicsCell(worldPos, terrainEntity, blockEntity, terrainChunk, blockChunkData);
+        if(cell == null){
+            posPhysicsMap.put(key, targetCell);
+        } else {
+            ServerEntityUtils.destroyEntity(terrainEntity);
+            ServerEntityUtils.destroyEntity(blockEntity);
+        }
+
         generationService.submit(() -> {
             //create physics entities
-            createTerrainPhysicsEntities(worldPos);
+            if(cell != null){
-            //set ready
+                cell.retireCell();
-            if(groundDataCells.get(getServerDataCellKey(worldPos)) != null){
+                cell.generatePhysics();
-                groundDataCells.get(getServerDataCellKey(worldPos)).setReady(true);
             } else {
-                LoggerInterface.loggerEngine.WARNING("Finished generating physics for server cell, but cell is null!");
+                targetCell.generatePhysics();
             }
+            //set ready
+            dataCell.setReady(true);
         });
-        groundDataCells.get(getServerDataCellKey(worldPos)).setReady(false);
     }
 
     /**
@@ -616,7 +687,9 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
         cellPositionMap.put(rVal,new Vector3i(worldPos));
         serverContentManager.generateContentForDataCell(parent, worldPos, rVal, cellKey);
         //generates physics for the cell in a dedicated thread then finally registers
-        this.runPhysicsGenerationThread(worldPos);
+        Long key = this.getServerDataCellKey(worldPos);
+        PhysicsDataCell cell = posPhysicsMap.get(key);
+        GriddedDataCellManager.runPhysicsGenerationThread(worldPos,key,cell,this.posPhysicsMap,this.groundDataCells,this.parent);
         return rVal;
     }
 
@@ -699,6 +772,7 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
                 serverTerrainManager.deformTerrainAtLocationToValue(toUpdate, new Vector3i(localVoxelX, localVoxelY, localVoxelZ), weight, type);
 
                 //update anything loaded
+                this.loadedCellsLock.lock();
                 ServerDataCell cell = groundDataCells.get(this.getServerDataCellKey(toUpdate));
                 if(cell != null){
                     //update physics
@@ -710,6 +784,7 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
                         localVoxelX, localVoxelY, localVoxelZ, 
                         weight, type));
                 }
+                this.loadedCellsLock.unlock();
             }
         }
         terrainEditLock.release();
@@ -747,20 +822,6 @@ public class GriddedDataCellManager implements DataCellManager, VoxelCellManager
         }
     }
 
-    /**
-     * Rebroadcasts the fluid cell at a given position
-     * @param worldPosition the world position
-     */
-    private void rebroadcastFluidChunk(Vector3i worldPosition){
-        Globals.profiler.beginAggregateCpuSample("GriddedDataCellManager.rebroadcastFluidChunk");
-        ServerDataCell cell = getCellAtWorldPosition(worldPosition);
-        ServerFluidChunk chunk = getFluidChunkAtPosition(worldPosition);
-        cell.broadcastNetworkMessage(
-            TerrainMessage.constructupdateFluidDataMessage(worldPosition.x, worldPosition.y, worldPosition.z, TerrainProtocol.constructFluidByteBuffer(chunk).array())
-        );
-        Globals.profiler.endCpuSample();
-    }
-
     @Override
     public void save(String saveName) {
         for(ServerDataCell cell : this.groundDataCells.values()){

src/main/java/electrosphere/server/datacell/RealmManager.java

@@ -1,9 +1,10 @@
 package electrosphere.server.datacell;
 
+import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArraySet;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.joml.Vector3d;
 
@@ -27,9 +28,14 @@ public class RealmManager {
     //All realms in this manager
     Set<Realm> realms = new CopyOnWriteArraySet<Realm>();
     //Map of entities to the realm the entity is in
-    Map<Entity,Realm> entityToRealmMap = new ConcurrentHashMap<Entity,Realm>();
+    Map<Entity,Realm> entityToRealmMap = new HashMap<Entity,Realm>();
     //Map of player to the realm the player is in
-    Map<Player,Realm> playerToRealmMap = new ConcurrentHashMap<Player,Realm>();
+    Map<Player,Realm> playerToRealmMap = new HashMap<Player,Realm>();
+
+    /**
+     * Lock for thread-safing the manager
+     */
+    ReentrantLock lock = new ReentrantLock();
 
     /**
      * Constructor
@@ -126,7 +132,9 @@ public class RealmManager {
      * @param realm The realm
      */
     public void mapEntityToRealm(Entity entity, Realm realm){
+        lock.lock();
         entityToRealmMap.put(entity, realm);
+        lock.unlock();
     }
 
     /**
@@ -134,7 +142,9 @@ public class RealmManager {
      * @param entity The entity to remove
      */
     public void removeEntity(Entity entity){
+        lock.lock();
         entityToRealmMap.remove(entity);
+        lock.unlock();
     }
 
     /**
@@ -143,7 +153,10 @@ public class RealmManager {
      * @return The realm, or null if the entity is not inside a realm
      */
     public Realm getEntityRealm(Entity entity){
-        return entityToRealmMap.get(entity);
+        lock.lock();
+        Realm rVal = entityToRealmMap.get(entity);
+        lock.unlock();
+        return rVal;
     }
 
     /**
@@ -173,7 +186,9 @@ public class RealmManager {
      * @param realm The realm
      */
     public void setPlayerRealm(Player player, Realm realm){
+        lock.lock();
         playerToRealmMap.put(player, realm);
+        lock.unlock();
     }
 
     /**
@@ -182,7 +197,10 @@ public class RealmManager {
      * @return The realm
      */
     public Realm getPlayerRealm(Player player){
-        return playerToRealmMap.get(player);
+        lock.lock();
+        Realm rVal = playerToRealmMap.get(player);
+        lock.unlock();
+        return rVal;
     }
 
     /**
@@ -221,8 +239,10 @@ public class RealmManager {
             }
         }
         this.realms.clear();
+        lock.lock();
         this.entityToRealmMap.clear();
         this.playerToRealmMap.clear();
+        lock.unlock();
     }
 
     /**

src/main/java/electrosphere/server/datacell/physics/PhysicsDataCell.java

@@ -1,5 +1,6 @@
 package electrosphere.server.datacell.physics;
 
+import electrosphere.client.block.BlockChunkData;
 import electrosphere.client.terrain.cache.ChunkData;
 import electrosphere.engine.Globals;
 import electrosphere.entity.Entity;
@@ -11,9 +12,7 @@ import electrosphere.renderer.meshgen.BlockMeshgen;
 import electrosphere.renderer.meshgen.BlockMeshgen.BlockMeshData;
 import electrosphere.server.datacell.Realm;
 import electrosphere.server.terrain.manager.ServerTerrainChunk;
-import electrosphere.server.terrain.manager.ServerTerrainManager;
 
-import org.joml.Vector3d;
 import org.joml.Vector3i;
 import org.ode4j.ode.DBody;
 
@@ -26,12 +25,12 @@ public class PhysicsDataCell {
     
     Entity physicsEntity;
     Entity blockPhysicsEntity;
+
+    ServerTerrainChunk terrainChunk;
+    BlockChunkData blockChunk;
     
     DBody physicsObject;
 
-    Realm realm;
-    ServerTerrainManager serverTerrainManager;
-
     float[][][] weights = new float[ServerTerrainChunk.CHUNK_DATA_GENERATOR_SIZE][ServerTerrainChunk.CHUNK_DATA_GENERATOR_SIZE][ServerTerrainChunk.CHUNK_DATA_GENERATOR_SIZE];
     int[][][] types = new int[ServerTerrainChunk.CHUNK_DATA_GENERATOR_SIZE][ServerTerrainChunk.CHUNK_DATA_GENERATOR_SIZE][ServerTerrainChunk.CHUNK_DATA_GENERATOR_SIZE];
     
@@ -47,13 +46,19 @@ public class PhysicsDataCell {
      * @return The cell
      */
     public static PhysicsDataCell createPhysicsCell(
-        Realm realm,
+        Vector3i worldPos,
-        Vector3i worldPos
+        Entity physicsEntity,
+        Entity blockPhysicsEntity,
+        ServerTerrainChunk currentChunk,
+        BlockChunkData blockChunk
+
     ){
         PhysicsDataCell rVal = new PhysicsDataCell();
-        rVal.realm = realm;
+        rVal.physicsEntity = physicsEntity;
-        rVal.serverTerrainManager = realm.getServerWorldData().getServerTerrainManager();
+        rVal.blockPhysicsEntity = blockPhysicsEntity;
         rVal.worldPos = worldPos;
+        rVal.blockChunk = blockChunk;
+        rVal.terrainChunk = currentChunk;
         return rVal;
     }
     
@@ -72,31 +77,17 @@ public class PhysicsDataCell {
      */
     public void generatePhysics(){
         //if the entity hasn't already been created for some reason, need to create it
-        if(physicsEntity == null){
             
-            //
+        //
-            //fill in weights and types maps
+        //fill in weights and types maps
-            //
+        //
-            this.fillInData();
+        this.fillInData();
 
-            Vector3d realPos = new Vector3d(
+        TerrainChunk.serverCreateTerrainChunkEntity(physicsEntity, weights, types);
-                worldPos.x * ServerTerrainChunk.CHUNK_PLACEMENT_OFFSET,
+        physicsEntity.putData(EntityDataStrings.TERRAIN_IS_TERRAIN, true);
-                worldPos.y * ServerTerrainChunk.CHUNK_PLACEMENT_OFFSET,
+        BlockMeshData meshData = BlockMeshgen.rasterize(blockChunk);
-                worldPos.z * ServerTerrainChunk.CHUNK_PLACEMENT_OFFSET
+        BlockChunkEntity.serverCreateBlockChunkEntity(blockPhysicsEntity, meshData);
-            );
+        blockPhysicsEntity.putData(EntityDataStrings.TERRAIN_IS_TERRAIN, true);
-            physicsEntity = TerrainChunk.serverCreateTerrainChunkEntity(realm, realPos, weights, types);
-            physicsEntity.putData(EntityDataStrings.TERRAIN_IS_TERRAIN, true);
-        }
-        if(blockPhysicsEntity == null){
-            Vector3d realPos = new Vector3d(
-                worldPos.x * ServerTerrainChunk.CHUNK_PLACEMENT_OFFSET,
-                worldPos.y * ServerTerrainChunk.CHUNK_PLACEMENT_OFFSET,
-                worldPos.z * ServerTerrainChunk.CHUNK_PLACEMENT_OFFSET
-            );
-            BlockMeshData meshData = BlockMeshgen.rasterize(realm.getServerWorldData().getServerBlockManager().getChunk(worldPos.x, worldPos.y, worldPos.z));
-            blockPhysicsEntity = BlockChunkEntity.serverCreateBlockChunkEntity(realm, realPos, meshData);
-            blockPhysicsEntity.putData(EntityDataStrings.TERRAIN_IS_TERRAIN, true);
-        }
         // //then actually perform the attach
         // physicsObject = PhysicsUtils.attachTerrainRigidBody(physicsEntity,heightmap,true);
         // Realm realm = Globals.realmManager.getEntityRealm(physicsEntity);
@@ -120,12 +111,11 @@ public class PhysicsDataCell {
         //fill in data
         //
         //main chunk
-        ServerTerrainChunk currentChunk = serverTerrainManager.getChunk(worldPos.x, worldPos.y, worldPos.z);
         for(int x = 0; x < ChunkData.CHUNK_DATA_SIZE; x++){
             for(int y = 0; y < ChunkData.CHUNK_DATA_SIZE; y++){
                 for(int z = 0; z < ChunkData.CHUNK_DATA_SIZE; z++){
-                    weights[x][y][z] = currentChunk.getWeight(x,y,z);
+                    weights[x][y][z] = terrainChunk.getWeight(x,y,z);
-                    types[x][y][z] = currentChunk.getType(x,y,z);
+                    types[x][y][z] = terrainChunk.getType(x,y,z);
                 }
             }
         }

src/main/java/electrosphere/server/fluid/manager/ServerFluidManager.java

@@ -14,11 +14,13 @@ import electrosphere.util.annotation.Exclude;
 
 import java.nio.ByteBuffer;
 import java.nio.FloatBuffer;
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Consumer;
 
 import org.joml.Vector3i;
 
@@ -30,7 +32,7 @@ public class ServerFluidManager {
     /**
      * DEfault size of the cache
      */
-    static final int DEFAULT_CACHE_SIZE = 500;
+    static final int DEFAULT_CACHE_SIZE = 50;
 
     /**
      * The number of frames to wait between updates
@@ -88,13 +90,13 @@ public class ServerFluidManager {
     /**
      * The queued of chunks to simulate
      */
-    List<ServerFluidChunk> simulationQueue = new LinkedList<ServerFluidChunk>();
+    List<ServerFluidChunk> simulationQueue = new ArrayList<ServerFluidChunk>();
 
     @Exclude
     /**
      * The queue of chunks to broadcast
      */
-    List<ServerFluidChunk> broadcastQueue = new LinkedList<ServerFluidChunk>();
+    List<ServerFluidChunk> broadcastQueue = new ArrayList<ServerFluidChunk>();
 
     @Exclude
     /**
@@ -287,14 +289,16 @@ public class ServerFluidManager {
      * @param worldZ The world z coordinate of the chunk
      */
     public void queue(int worldX, int worldY, int worldZ){
-        ServerFluidChunk fluidChunk = this.getChunk(worldX, worldY, worldZ);
+        if(simulate){
-        this.simulationQueue.add(fluidChunk);
+            ServerFluidChunk fluidChunk = this.getChunk(worldX, worldY, worldZ);
+            this.simulationQueue.add(fluidChunk);
+        }
     }
 
     /**
      * Simulates a chunk
      */
-    public void simulate(){
+    public void simulate(Consumer<ServerFluidChunk> onUpdate){
         Globals.profiler.beginAggregateCpuSample("ServerFluidManager.simulate");
         lock.lock();
         if(simulate){
@@ -304,8 +308,15 @@ public class ServerFluidManager {
                 }
             }
             
-            this.simulationQueue.clear();
+            //clear both queues
+            while(this.simulationQueue.size() > 0){
+                this.simulationQueue.remove(0);
+            }
             this.broadcastSize = this.broadcastQueue.size();
+            while(this.broadcastQueue.size() > 0){
+                ServerFluidChunk toBroadcast = this.broadcastQueue.remove(0);
+                onUpdate.accept(toBroadcast);
+            }
 
             updatePhase++;
             if(updatePhase > UPDATE_RATE){