--- a/TaskManager/Gpu/GpuScheduler.cc	Fri Dec 13 17:13:53 2013 +0900
+++ b/TaskManager/Gpu/GpuScheduler.cc	Fri Dec 13 20:46:46 2013 +0900
@@ -54,6 +54,7 @@
         const char *msg=convert_error_status(ret);
         error(msg);
     }
+
 }
 
 GpuScheduler::~GpuScheduler()
@@ -115,18 +116,19 @@
         kernel_event[1-cur] = 0;
     }
     if (memout[1-cur].size > 0) {
-        for (int i=0; i < memout[1-cur].size; i++) {
-            int ret=clWaitForEvents(memout[1-cur].size, &memout[1-cur].event[i]);
-            if (ret<0) {
-                error(convert_error_status(ret));
-            }
+
+        int ret=clWaitForEvents(memout[1-cur].size, memout[1-cur].event);
+        if (ret<0) {
+            error(convert_error_status(ret));
         }
+
         for (int i=0; i < memout[1-cur].size; i++) {
             clReleaseEvent(memout[1-cur].event[i]);
             memout[1-cur].event[i] = 0;
             clReleaseMemObject(memout[1-cur].buf[i]);
             memout[1-cur].buf[i]   = 0;
         }
+        memout[1-cur].size = 0;
     }
 
     if (memin[1-cur].size > 0) {
@@ -136,6 +138,7 @@
             clReleaseMemObject(memin[1-cur].buf[i]);
             memin[1-cur].buf[i]   = 0;
         }
+        memin[1-cur].size = 0;
     }
 
     if(reply[1-cur]) {
@@ -393,10 +396,13 @@
 GpuScheduler::load_kernel(int cmd)
 {
     if (gpu_task_list[cmd].run == null_run) {
+        return 1;
+    }
+
+    if (gpu_task_list[cmd].gputask == 0 || gpu_task_list[cmd].gputask->program == 0) {
         fprintf(stderr, "GPU kernel %d not defined.\n",cmd);
         return 0;
     }
-
     const char *filename = (const char *)gpu_task_list[cmd].gputask->program;
 
     int fd;