Processes Limit

What is a Process?

Processes refer to the tasks a server carries out when running commands—like checking your email or opening a message. These tasks are handled through multiple processes that usually finish within seconds. The number of processes you can run at once depends on the type of hosting plan your account uses.

This article discusses the following topics.

• Concurrent Processes Limitation
• Mail Client Exceeding Processes Limit
• VPS or Dedicated server is Limiting Me to 25 Processes
• Summary
   

Concurrent Processes limitation

Shared and Reseller hosting

Shared and Reseller hosting accounts can run up to 25 active processes at the same time for each cPanel. For most websites, this limit is more than enough, since processes start and finish so quickly that they rarely overlap.

If a user has between 15 and 19 IMAP processes running, the system will automatically terminate any process that has been active for more than five minutes. Once the number of IMAP processes reaches 20 or more, the system shortens this window and ends any process that has been running for over two minutes.

SSH access is limited to two simultaneous connections on Shared and Reseller plans.

VPS and Dedicated hosting

VPS and Dedicated hosting plans let you set your own limit for simultaneous processes, with no fixed cap imposed.

Mail client exceeding the Processes limit

If you go over the process limit, it may be because your email application (such as Thunderbird, Mac Mail, or Outlook) is checking the server for new messages too frequently within an hour.

Mail Policy

When this limit is hit, the server queues each additional mail check as a pending process until the 30‑check window resets. However, if your mail client continues sending requests, those processes keep stacking up. Eventually, they accumulate to the 25‑process cap, which can cause your website to crash and display a 500 error.

How to determine if your email client is the problem

Try the steps below to check whether your email client is the reason your site is hitting the process limits.

1. Close your email application to clear out any active processes. Once it’s fully closed, your website should begin loading normally again.
2. Once your site is loading again, reopen your email client and find the setting that controls how often it checks for new messages. Make sure the interval is set to at least 10 minutes.

If you continue hitting the process limit, it may indicate that your website is receiving more traffic than a Shared hosting plan can handle, or that your database needs optimization to improve query speed.

VPS or Dedicated server is limiting me to 25 processes

This number can be increased at your discretion by making changes in the following file: /usr/local/apache/conf/includes/pre_main_global.conf

To make the appropriate changes, use the command line:

    RLimitNPROC 25 30

1. Change the first number to the new limit (in the command above, it is 25).
2. Add 5 to get the second number (in the command above, 30).
3. Restart Apache (location: /etc/init.d/httpd, command: restart).

After Apache is restarted, you should be able to see the new process limit functioning accordingly.

Summary

This article explains how process limits work on different hosting plans. Shared and Reseller accounts allow up to 25 concurrent processes, while VPS and Dedicated servers have adjustable limits. It also highlights how email clients checking too frequently can exceed these limits and cause website errors. Troubleshooting steps and guidance for increasing process limits on VPS/Dedicated servers are included.