diff --git a/.gitignore b/.gitignore
index fa48430..fe9d838 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,3 +36,4 @@ tests/*.exp
 tests/*.log
 tests/*.sh
 core.*
+ftp-sync.json
diff --git a/.travis.yml b/.travis.yml
index b891189..6b4aa69 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -7,12 +7,13 @@ compiler:
     - gcc
 
 php:
-    - '5.4'
-    - '5.5'
-    - '5.6'
-    - '7.0'
-    - '7.1'
-    - '7.2'
+    #- '5.4'
+    #- '5.5'
+    #- '5.6'
+    - '7.0.17'
+    - '7.0.18'
+    - '7.1.7'
+    - '7.2.0'
 
 before_install:
     - php --ini
diff --git a/src/phpgo_context.h b/src/phpgo_context.h
index 18fa79f..c250079 100644
--- a/src/phpgo_context.h
+++ b/src/phpgo_context.h
@@ -212,12 +212,12 @@ do{ \
 #endif
 
 struct PhpgoBaseContext{
+	uint64_t                   guard__[64];
 	uint64_t                   task_id;
 	bool                       http_globals_cleanup_required;
 
 #if PHP_MAJOR_VERSION < 7
 	/*go routine running environment*/
-	struct _zend_execute_data* EG_current_execute_data; 
 	zend_vm_stack 			   EG_argument_stack;       
 	zend_class_entry*		   EG_scope;                
 	zval*					   EG_This;                 
@@ -236,7 +236,6 @@ struct PhpgoBaseContext{
 	TSRMLS_FIELD;  /*ZTS: void ***tsrm_ls;*/
 #else 
 	/* php7 */
-	struct _zend_execute_data* EG_current_execute_data; 
 	zend_vm_stack			   EG_vm_stack;
     zval*                      EG_vm_stack_top;
     zval*                      EG_vm_stack_end;
@@ -244,9 +243,16 @@ struct PhpgoBaseContext{
 	zval                       PG_http_globals[NUM_TRACK_VARS];
 	zval                       http_request_global;
 #endif
+
+	struct _zend_execute_data* EG_current_execute_data;
+	JMP_BUF*                   EG_bailout;
+
+	uint64_t                   __guard[64];
 	/**/
 	PhpgoBaseContext(){
 		bzero(this, sizeof(*this));
+		memset(guard__, 0xcc, sizeof(guard__));
+		memset(__guard, 0xcc, sizeof(__guard));
 		
 		PHP7_AND_ABOVE(
 			for(int i=0; i< NUM_TRACK_VARS; i++)
@@ -286,6 +292,14 @@ struct PhpgoBaseContext{
         this->EG_vm_stack_top          =  EG(vm_stack_top            );
 		this->EG_vm_stack_end          =  EG(vm_stack_end            );
 #endif
+		for(int i=0; i<64; i++){
+			if (guard__[i]!=0xcccccccccccccccc) {
+				printf("!!!: guard__ was overwritten! address: %p, value:%lx\n", &guard__[i], guard__[i]);
+			}
+			if (__guard[i]!=0xcccccccccccccccc) {
+				printf("!!!: __guard was overwritten! address: %p, value:%lx\n", &__guard[i], __guard[i]);
+			}
+		}
 	}
 
 	inline void SwapIn(bool include_http_globals){
@@ -318,6 +332,15 @@ struct PhpgoBaseContext{
 			REPLACE_PG_HTTP_GLOBALS_WITH(this->PG_http_globals);
 			SET_HTTP_GLOBALS(this->PG_http_globals, this->http_request_global);  		
 		}
+
+		for(int i=0; i<64; i++){
+			if (guard__[i]!=0xcccccccccccccccc) {
+				printf("!!!: guard__ was overwritten! address: %p, value:%lx\n", &guard__[i], guard__[i]);
+			}
+			if (__guard[i]!=0xcccccccccccccccc) {
+				printf("!!!: __guard was overwritten! address: %p, value:%lx\n", &__guard[i], __guard[i]);
+			}
+		}
 	}
 
 public: