Sites on Plesk loading slowly: high TTFB and CPU usage by Apache

Symptoms

• The following error message can be found in Apache error log /var/log/httpd/error_log:

  [log_config:warn] [pid 5774] (32)Broken pipe: [client 203.0.113.2:43955] AH00646: Error writing to |/usr/local/psa/admin/sbin/pipelog 443, referer: http://example.com/

• High CPU usage by Apache is displayed in Health Monitor.

• There is no DDOS attack on the server:

• Time to first byte / Start transfer time for websites hosted on the server is high:

  # curl -s -w 'nLookup time:tt%{time_namelookup}nConnect time:tt%{time_connect}nSSL handshake time:t%{time_appconnect}nPre-Transfer time:t%{time_pretransfer}nRedirect time:tt%{time_redirect}nTime to first byte:t%{time_starttransfer}nnTotal time:tt%{time_total}n' -o /dev/null http://example.com

  Time to first byte: 25.204602

Cause

The enabled Piped logs feature slows down Apache performance.

Resolution

1. Log in to Plesk.

2. Disable the Piped logs feature in Tools & Settings > Apache Web Server.