The function is in file ngx_event_pipe.c,it is not too long,but i am confused by it. when i debug it,it always says buf->shadow is NULL,and then return.so i think it is useless.At the same time,i am confused how can cl->buf equal s.Thanks for your explanations.The follow is the code. static ngx_inline void ngx_event_pipe_free_shadow_raw_buf(ngx_chain_t **free, ngx_buf_t *buf) {by lihongfu - Nginx Mailing List - English