9 files changed, 35 insertions, 19 deletions
diff --git a/src/com/jogamp/opencl/CLBuffer.java b/src/com/jogamp/opencl/CLBuffer.java
index 03e07477..d4e0d003 100644
--- a/src/com/jogamp/opencl/CLBuffer.java
+++ b/src/com/jogamp/opencl/CLBuffer.java
@@ -127,7 +127,7 @@ public class CLBuffer<B extends Buffer> extends CLMemory<B> {
     }
 
     @Override
-    public void release() {
+    public synchronized void release() {
         if(childs != null) {
             while(!childs.isEmpty()) {
                 childs.get(0).release();
diff --git a/src/com/jogamp/opencl/CLCommandQueue.java b/src/com/jogamp/opencl/CLCommandQueue.java
index b1644cf2..016192c3 100644
--- a/src/com/jogamp/opencl/CLCommandQueue.java
+++ b/src/com/jogamp/opencl/CLCommandQueue.java
@@ -1796,7 +1796,7 @@ public class CLCommandQueue extends CLObjectResource {
     }
 
     @Override
-    public void release() {
+    public synchronized void release() {
         super.release();
         int ret = cl.clReleaseCommandQueue(ID);
         context.onCommandQueueReleased(device, this);
diff --git a/src/com/jogamp/opencl/CLContext.java b/src/com/jogamp/opencl/CLContext.java
index 54f95728..928adabb 100644
--- a/src/com/jogamp/opencl/CLContext.java
+++ b/src/com/jogamp/opencl/CLContext.java
@@ -510,13 +510,27 @@ public class CLContext extends CLObjectResource {
     public void removeCLErrorHandler(CLErrorHandler handler) {
         errorHandler.removeHandler(handler);
     }
-    
+
+    /*
+     * We have a hierarchy of resources and we don't want any
+     * global lock in the create or release methods. context.release() releases the whole hierarchy
+     * but in the meantime a other thread could have already release a child resource.
+     */
     private void release(Collection<? extends CLResource> resources) {
         // resources remove themselves when released, see above
         if(!resources.isEmpty()) {
-            CLResource[] array = resources.toArray(new CLResource[resources.size()]);
+            // copy to workaround concurrent modification exceptions
+            CLResource[] array = null;
+            synchronized(resources) {
+                array = resources.toArray(new CLResource[resources.size()]);
+            }
             for (CLResource resource : array) {
-                resource.release();
+                synchronized(resource) {
+                    // released==true can only happen if an other thread released the resource while we where iterating
+                    if(!resource.isReleased()) {
+                        resource.release();
+                    }
+                }
             }
         }
     }
diff --git a/src/com/jogamp/opencl/CLKernel.java b/src/com/jogamp/opencl/CLKernel.java
index 7d5751fd..4d06d8b9 100644
--- a/src/com/jogamp/opencl/CLKernel.java
+++ b/src/com/jogamp/opencl/CLKernel.java
@@ -632,7 +632,7 @@ public class CLKernel extends CLObjectResource implements Cloneable {
      * Releases all resources of this kernel from its context.
      */
     @Override
-    public void release() {
+    public synchronized void release() {
         super.release();
         int ret = binding.clReleaseKernel(ID);
         program.onKernelReleased(this);
diff --git a/src/com/jogamp/opencl/CLMemory.java b/src/com/jogamp/opencl/CLMemory.java
index 0edfb7e2..eee025e6 100644
--- a/src/com/jogamp/opencl/CLMemory.java
+++ b/src/com/jogamp/opencl/CLMemory.java
@@ -221,7 +221,7 @@ public abstract class CLMemory <B extends Buffer> extends CLObjectResource {
     }
 
     @Override
-    public void release() {
+    public synchronized void release() {
         super.release();
         int ret = binding.clReleaseMemObject(ID);
         context.onMemoryReleased(this);
diff --git a/src/com/jogamp/opencl/CLObjectResource.java b/src/com/jogamp/opencl/CLObjectResource.java
index 3a8fe500..f11e4f97 100644
--- a/src/com/jogamp/opencl/CLObjectResource.java
+++ b/src/com/jogamp/opencl/CLObjectResource.java
@@ -11,7 +11,7 @@ import com.jogamp.common.AutoCloseable;
  */
 abstract class CLObjectResource extends CLObject implements CLResource, AutoCloseable {
 
-    private boolean released;
+    protected volatile boolean released;
 
     public CLObjectResource(long ID) {
         super(ID);
diff --git a/src/com/jogamp/opencl/CLProgram.java b/src/com/jogamp/opencl/CLProgram.java
index 3fcee4a7..f8c83def 100644
--- a/src/com/jogamp/opencl/CLProgram.java
+++ b/src/com/jogamp/opencl/CLProgram.java
@@ -70,11 +70,10 @@ public class CLProgram extends CLObjectResource {
     private Map<CLDevice, Status> buildStatusMap;
 
     private boolean executable;
-    private boolean released;
 
     private CLProgram(CLContext context, long id) {
         super(context, id);
-        this.kernels = new HashSet<CLKernel>();
+        this.kernels = Collections.synchronizedSet(new HashSet<CLKernel>());
         this.binding = context.getPlatform().getProgramBinding();
     }
     
@@ -486,13 +485,12 @@ public class CLProgram extends CLObjectResource {
      * Releases this program with its kernels.
      */
     @Override
-    public void release() {
+    public synchronized void release() {
 
         super.release();
         releaseKernels();
 
         executable = false;
-        released = true;
         buildStatusMap = null;
         
         int ret = binding.clReleaseProgram(ID);
@@ -503,11 +501,15 @@ public class CLProgram extends CLObjectResource {
     }
 
     private void releaseKernels() {
-        if(!kernels.isEmpty()) {
-            // copy to array to prevent concurrent modification exception
-            CLKernel[] array = kernels.toArray(new CLKernel[kernels.size()]);
-            for (CLKernel kernel : array) {
-                kernel.release();
+        synchronized(kernels) {
+            if(!kernels.isEmpty()) {
+                // copy to array to prevent concurrent modification exception
+                CLKernel[] array = kernels.toArray(new CLKernel[kernels.size()]);
+                for (CLKernel kernel : array) {
+                    if(!kernel.isReleased()) {
+                        kernel.release();
+                    }
+                }
             }
         }
     }
diff --git a/src/com/jogamp/opencl/CLSampler.java b/src/com/jogamp/opencl/CLSampler.java
index 3f145b3b..c5b01c8b 100644
--- a/src/com/jogamp/opencl/CLSampler.java
+++ b/src/com/jogamp/opencl/CLSampler.java
@@ -79,7 +79,7 @@ public class CLSampler extends CLObjectResource {
     }
 
     @Override
-    public void release() {
+    public synchronized void release() {
         super.release();
         int ret = binding.clReleaseSampler(ID);
         context.onSamplerReleased(this);
diff --git a/src/com/jogamp/opencl/CLSubBuffer.java b/src/com/jogamp/opencl/CLSubBuffer.java
index d8831783..758ccf66 100644
--- a/src/com/jogamp/opencl/CLSubBuffer.java
+++ b/src/com/jogamp/opencl/CLSubBuffer.java
@@ -57,7 +57,7 @@ public class CLSubBuffer<B extends Buffer> extends CLBuffer<B> {
     }
 
     @Override
-    public void release() {
+    public synchronized void release() {
         parent.onReleaseSubBuffer(this);
         super.release();
     }