Error 503 Backend fetch failed怎么办

1、为了解决这个问题，修改varnish配置文件如下:1.用root用户打开:CentOS 6:/etc/sysconfig/varnishCentOS 7:/etc/varnish/varnish.paramsUbuntu:/etc/default/varnish

2、搜索http_resp_hdr_len参数

3、如果参数不存在增加thread_pool_max

4、设置http_resp_hdr娄多骋能_len示例:-p http_resp_hdr_len=64000 \代码片段:# DAEMON_OPTS is used by the init script.肛舀辨乔DAEMON_OPTS="-a ${VARNISH_LISTEN_ADDRESS}:${VARNISH_LISTEN_PORT} \ -f ${VARNISH_VCL_CONF} \ -T ${VARNISH_ADMIN_LISTEN_ADDRESS}:${VARNISH_ADMIN_LISTEN_PORT} \ -p thread_pool_min=${VARNISH_MIN_THREADS} \ -p thread_pool_max=${VARNISH_MAX_THREADS} \ -p http_resp_hdr_len=64000 \ -S ${VARNISH_SECRET_FILE} \ -s ${VARNISH_STORAGE}"