我设置了Apache来代理tomcat，但是当我定位页面时出现以下错误。 我有时会得到一个空白页面或503：
[错误]
[Mon Dec 03 04:58:16 2012] [error] proxy: ap_get_scoreboard_lb(2) failed in child 29611 for worker proxy:reverse [Mon Dec 03 04:58:16 2012] [error] proxy: ap_get_scoreboard_lb(1) failed in child 29611 for worker https://localhost:8443/ [Mon Dec 03 04:58:16 2012] [error] proxy: ap_get_scoreboard_lb(0) failed in child 29611 for worker http://localhost:8080/ 我在vm上configuration了两个虚拟主机，如下所示：
[http主机]
<VirtualHost *:80> ServerName www.mysite.net ServerAlias mysite.net ProxyRequests Off ProxyPreserveHost On <Proxy *> Order deny,allow Allow from all </Proxy> ProxyPass / http://localhost:8080/ retry=0 ProxyPassReverse / http://localhost:8080/ retry=0 </VirtualHost>
[ssl vhost]
<VirtualHost *:443> ServerName www.mysite.net ServerAlias mysite.net ErrorLog /var/log/apache2/error.log LogLevel warn CustomLog /var/log/apache2/access.log combined ServerSignature On SSLEngine on SSLProxyEngine on SSLCertificateFile /etc/apache2/ssl/server.crt SSLCertificateKeyFile /etc/apache2/ssl/server.key ProxyRequests Off ProxyPreserveHost On ProxyPass / https://localhost:8443/ retry=0 ProxyPassReverse / https://localhost:8443/ retry=0 </VirtualHost>
我的系统详细信息是：Apache / 2.2.22（Ubuntu）mod_jk / 1.2.32 mod_ssl / 2.2.22 OpenSSL / 1.0.1 mod proxy_http也被启用。
看起来有停止，然后启动apache和做一个apachectl graceful重新启动（即实际上停止和启动，而不是apachectl重新启动 ）在这个网站上find一个区别：
This is a bit of a guess, and probably wrong, but does stopping and starting the server rather than restarting (they're different, restarting (including gracefully) doesn't kill the master process) help? As I understand it, there are issues in mod_proxy regarding the scoreboard size when changes to the config are made between restarts.