Symptoms

In Apache NG cluster, websites operation is slow.

LVE on NG Webservers is enabled and all limits in subscription are enough for fast website response.

Possible network-related and NFS storage related issue have been excluded from the investigation as unrelated.

Cause

Starting from POA 5.5.5 there is internal throttling functionality implemented that increased response time for every next dynamic request for sits that generate many (60-100 or even more) dynamic requests per minute. This functionality was added to prevent DDoS attacks on some websites (especially for installations where LVE is off). However, it also causes slowness of web sites.

Resolution

It is impossible to disable it currently, request to disable this throttling mechanism was submitted to maintenance team as POA-86646, fixed in 5.5.7. Since this version, throttling is enabled automatically only if LVE is disabled in /etc/httpd/conf.d/modsucgid.conf.

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