Resource limits on shared hosting
On shared hosting, many websites run on the same server. To keep one busy or faulty site from slowing down all the others, each hosting account gets a fair share of the server's resources. This guide explains what each limit measures, the signs that your site has reached one, and how to bring usage down before deciding whether you need a bigger plan.
What each limit means
| Resource | What it measures | What uses it |
|---|---|---|
| CPU | Processing power, often shown as a percentage of one processor core | Building pages, running plugins, search, imports, cron jobs |
| Memory (RAM) | Working memory used by your site's processes at the same time | Every running PHP process; heavy plugins use more |
| Processes | How many programs your account may run at once | PHP, cron jobs, scripts, email processes |
| Entry processes | How many requests may be handled at the same moment, roughly the number of visitors your site serves in parallel | Page loads, admin screens, bots and crawlers |
| Inodes | The number of files and folders, whatever their size | Cache files, email messages, backups, session files |
| Disk space | Total storage used | Files, databases, email, backups and logs |
| Bandwidth | Data sent to and from your site over a period, usually a month | Page views, images, video and downloads |
Entry processes and processes measure how many things happen at once, not in total. A site with many visitors spread over the day can stay within limits, while a burst of simultaneous requests, such as an aggressive crawler, can reach them in seconds.
Your hosting plan or account usually shows your current usage and limits. Where to find them depends on your host.
Signs you have reached a limit
- 503 Service Unavailable or 508 Resource Limit Is Reached errors, often only for some visitors or for a few minutes at a time.
- Pages that load slowly at busy times but are fine at quiet ones.
- The admin area of your website app becomes slow or times out.
- Uploads, emails or new files fail, which can mean the disk or inode limit is full.
- Cron jobs or imports stop part way through.
When a limit is reached, the server usually slows down or queues your site's requests rather than stopping it entirely. Usage graphs in your hosting account can show which limit was hit and when.
Reduce your usage
Most limit problems come from a few causes. Work through these before upgrading.
Use caching
Without caching, every page view runs PHP code and database queries. A page cache saves the finished page and serves the copy to the next visitor, which uses far less CPU and memory. Most website apps support caching through a built-in setting, an extension or a plugin.
Control bots and crawlers
Automated traffic can use more resources than real visitors. Check your site's access logs or statistics for addresses or user agents making large numbers of requests.
- Block bots you don't want, using your website's security tools or firewall rules.
- Use a
robots.txtfile to keep well-behaved crawlers out of areas such as search results and filtered product listings. Badly behaved bots ignore it, so blocking may still be needed. - Protect login pages from repeated sign-in attempts, see Protect your hosting account.
Review cron jobs
Jobs that run every minute, or that overlap with each other, add constant load. Run them less often and spread them out, see Schedule tasks with cron jobs.
Clean up files
- Delete old backups stored inside your hosting account once you have a copy elsewhere.
- Remove unused themes, plugins and old copies of the site, such as
old-siteortestfolders. - Clear old cache, log and session files, which can add up to many thousands of inodes.
- Empty large mailboxes, or archive old messages to your computer.
Fix slow code
A single slow plugin, theme or database query can account for most of a site's load. Update everything to current versions, remove plugins you don't use, and test with problem plugins switched off to find the cause. A current, supported PHP version also helps, see PHP versions and settings.
When to upgrade
Consider a larger plan when:
- you have applied caching, controlled bots and cleaned up, and you still reach limits regularly
- your traffic has grown steadily from real visitors, not from bots
- you need to run tasks that shared hosting is not designed for, such as long-running processes or custom server software
For sites that outgrow shared hosting, a VPS or cloud server gives you dedicated resources in exchange for managing the server yourself. Web hosting, VPS or cloud compares the options.