Applicable to:
- Plesk for Linux
Symptoms
-
High CPU usage by Apache is displayed in Health Monitor.
-
There is no DDOS attack on the server:
# netstat -an | egrep ':80|:443' | grep ESTABLISHED | awk '{print $5}' | grep -o -E "([0-9]{1,3}[\.]){3}[0-9]{1,3}" | sort -n | uniq -c | sort -nr
11 203.0.113.2
8 203.0.113.5
2 203.0.113.4 -
Time to first byte / Start transfer time for websites hosted on the server is high:
# curl -s -w '\nLookup time:\t\t%{time_namelookup}\nConnect time:\t\t%{time_connect}\nSSL handshake time:\t%{time_appconnect}\nPre-Transfer time:\t%{time_pretransfer}\nRedirect time:\t\t%{time_redirect}\nTime to first byte:\t%{time_starttransfer}\n\nTotal time:\t\t%{time_total}\n' -o /dev/null http://example.com
Lookup time: 0.001502
Connect time: 0.120165
SSL handshake time: 0.000000
Pre-Transfer time: 0.120240
Redirect time: 0.000000
Time to first byte: 25.204602 -
Piped logs feature is enabled in Tools & Settings > Apache Web Server.
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In some cases, the following error message can be found in Apache error log
/var/log/httpd/error_log
:CONFIG_TEXT: [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/
Cause
The enabled Piped logs feature slows down Apache performance.
Resolution
-
Disable the Piped logs feature in Tools & Settings > Apache Web Server.
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