keytablelist bugfix (#2835)

src/bthread/key.cpp

@@ -34,12 +34,12 @@
 
 namespace bthread {
 
-DEFINE_uint32(key_table_list_size, 5000,
+DEFINE_uint32(key_table_list_size, 4000,
               "The maximum length of the KeyTableList. Once this value is "
               "exceeded, a portion of the KeyTables will be moved to the "
               "global free_keytables list.");
 
-DEFINE_uint32(borrow_from_globle_size, 100,
+DEFINE_uint32(borrow_from_globle_size, 200,
               "The maximum number of KeyTables retrieved in a single operation "
               "from the global free_keytables when no KeyTable exists in the "
               "current thread's keytable_list.");
@@ -289,11 +289,12 @@ class BAIDU_CACHELINE_ALIGNMENT KeyTableList {
             count++;
         }
         if (prev != NULL) {
-            prev->next = NULL;
             if (*target == NULL) {
                 *target = _head;
+                prev->next = NULL;
             } else {
-                (*target)->next = _head;
+                prev->next = *target;
+                *target = _head;
             }
             _head = current;
             _length -= count;