我有一台 Raspberry Pi 4，为 5 个不同的网站提供服务。其中 4 个只是静态的、最小的家庭项目网站，其中一个是通过反向代理运行的 snap Nextcloud 实例。我通过 certbot 配置了每个虚拟主机的 SSL，一切都运行正常，直到今天 Nextcloud 停止响应。
检查了所有其他域名后，我发现（巧合吗？）.com 域名没有响应，而其他域名有响应。
/var/log/apache2/error.log看起来像这样：
[Wed Oct 14 19:06:13.012069 2020] [mpm_event:error] [pid 2059:tid 281473471475728] AH03490: scoreboard is full, not at MaxRequestWorkers.Increase ServerLimit.
[Wed Oct 14 19:06:14.013288 2020] [mpm_event:error] [pid 2059:tid 281473471475728] AH03490: scoreboard is full, not at MaxRequestWorkers.Increase ServerLimit.
[Wed Oct 14 19:06:15.014486 2020] [mpm_event:error] [pid 2059:tid 281473471475728] AH03490: scoreboard is full, not at MaxRequestWorkers.Increase ServerLimit.
[Wed Oct 14 19:06:16.015707 2020] [mpm_event:error] [pid 2059:tid 281473471475728] AH03490: scoreboard is full, not at MaxRequestWorkers.Increase ServerLimit.
[Wed Oct 14 19:06:17.016931 2020] [mpm_event:error] [pid 2059:tid 281473471475728] AH03490: scoreboard is full, not at MaxRequestWorkers.Increase ServerLimit.
[Wed Oct 14 19:06:18.018247 2020] [mpm_event:error] [pid 2059:tid 281473471475728] AH03490: scoreboard is full, not at MaxRequestWorkers.Increase ServerLimit.
[Wed Oct 14 19:06:19.019550 2020] [mpm_event:error] [pid 2059:tid 281473471475728] AH03490: scoreboard is full, not at MaxRequestWorkers.Increase ServerLimit.
[Wed Oct 14 19:18:31.037054 2020] [mpm_event:notice] [pid 2059:tid 281473471475728] AH00493: SIGUSR1 received. Doing graceful restart
[Wed Oct 14 19:18:31.065424 2020] [mpm_event:notice] [pid 2059:tid 281473471475728] AH00489: Apache/2.4.41 (Ubuntu) OpenSSL/1.1.1f configured -- resuming normal operations
[Wed Oct 14 19:18:31.065478 2020] [core:notice] [pid 2059:tid 281473471475728] AH00094: Command line: '/usr/sbin/apache2'
sudo apachectl configtest显示 OK 语法并sudo systemctl status apache2.service -l --no-pager显示：
● apache2.service - The Apache HTTP Server
Loaded: loaded (/lib/systemd/system/apache2.service; enabled; vendor preset: enabled)
Active: active (running) since Wed 2020-10-14 17:53:55 UTC; 1h 49min ago
Docs: https://httpd.apache.org/docs/2.4/
Process: 1825 ExecStart=/usr/sbin/apachectl start (code=exited, status=0/SUCCESS)
Process: 307170 ExecReload=/usr/sbin/apachectl graceful (code=exited, status=0/SUCCESS)
Main PID: 2059 (apache2)
Tasks: 163 (limit: 9258)
CGroup: /system.slice/apache2.service
├─ 2059 /usr/sbin/apache2 -k start
├─307174 /usr/sbin/apache2 -k start
├─307175 /usr/sbin/apache2 -k start
├─307230 /usr/sbin/apache2 -k start
├─307258 /usr/sbin/apache2 -k start
├─307287 /usr/sbin/apache2 -k start
└─307315 /usr/sbin/apache2 -k start
Oct 14 18:56:38 raspberrypi4 systemd[1]: Reloading The Apache HTTP Server.
Oct 14 18:56:38 raspberrypi4 systemd[1]: Reloaded The Apache HTTP Server.
Oct 14 19:00:23 raspberrypi4 systemd[1]: Reloading The Apache HTTP Server.
Oct 14 19:00:23 raspberrypi4 systemd[1]: Reloaded The Apache HTTP Server.
Oct 14 19:05:02 raspberrypi4 systemd[1]: Reloading The Apache HTTP Server.
Oct 14 19:05:02 raspberrypi4 systemd[1]: Reloaded The Apache HTTP Server.
Oct 14 19:05:18 raspberrypi4 systemd[1]: Reloading The Apache HTTP Server.
Oct 14 19:05:18 raspberrypi4 systemd[1]: Reloaded The Apache HTTP Server.
Oct 14 19:18:30 raspberrypi4 systemd[1]: Reloading The Apache HTTP Server.
Oct 14 19:18:31 raspberrypi4 systemd[1]: Reloaded The Apache HTTP Server.
我对 Apache 的经验很少，尝试/etc/apache2/mods-available/mpm_prefork.conf添加 ServerLimit 指令（它不存在）并使用不同的值后，我仍未找到解决方案，因此我再次删除了 ServerLimit。有什么建议吗？该文件如下所示：
<IfModule mpm_prefork_module>
StartServers 5
MinSpareServers 5
MaxSpareServers 10
MaxRequestWorkers 150
MaxConnectionsPerChild 0
</IfModule>