Many server solutions like Apache, MySQL and CloudLinux have ways to limit resource usage of individual accounts in a shared hosting server. One commonly used resource limit is “Number of processes”.
What does exactly "Number of processes" means?
Each visit to a website in a shared server is made possible through a “process” in the server. Each process, in turn, uses up server resources such as Memory, CPU, etc. adding to the server load. So, limiting the number of processes effectively limits the resource usage, and denies one single account a monopoly over server resources.
In CloudLinux servers, “Number of processes” limit is known as “Entry process limit” or “EP limit”. By default, CloudLinux sets this limit as “20”, so that no website can have more than 20 simultaneous visitors at the same time. For an average shared hosting website, this default limit is adequate. When a website tries to open an additional connection over this limit, the error “508 Resource Limit Is Reached” is displayed.
Website abuse is the most common reason for this error to be shown. Situations such as DoS attacks, massive comment spamming and brute-force hack attempts easily exhaust the “Entry Process limit” and show the site as inaccessible. So, it is important to find what is causing the resource limit error before this issue can be resolved.
The process list also showed something very important – All the processes were requests to access “/home/username/public_html/xmlrpc.php“. “xmlrpc.php” is a file used by WordPress websites to track references of the website in other sites.
Valid increase in traffic
Some websites achieve a sudden increase of valid traffic, usually during a marketing campaign or during festive seasons. In such situations, the solution is to upgrade the “Entry Process limit”. In CloudLinux cPanel/WHM servers, it is modified by going to:
WHM Home >> Server Configuration >> CloudLinux LVE Manager >> Settings >> Edit >> Apply
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