helperSubmit 传递堆内存有问题，传进去栈内存可以

rt,待调查
如下，在回调时可以在prefetchHandleReply传回来

1. char buf[4096];
   
2. snprintf(buf, 4096, "%s\n", (char*)(req_param->urls).items[0]);
   
3. helperSubmit(prefetchers, buf, prefetchHandleReply, state);

如下却存在问题

1. typedef struct _request_param
   
2. {
   
3.         Array urls;
   
4. }request_param;
   
5. helperSubmit(prefetchers, (char*)(req_param->urls).items[0], prefetchHandleReply, state);