Traffic Spikes and the Shared Hosting Plan

The busiest hour of the year

A regional television show mentions your business at ten past seven in the morning. By half past, a few hundred people have typed your name into their phones.

The site slows, then shows a short error page instead of the home page. By the time anybody checks, the segment is over and the visitors have gone.

Nothing is broken, exactly. The hosting account has reached the limits its plan allows, and the server is turning people away to protect the other sites on it.

A big email promotion can do the same. So can the Black Friday weekend, which starts on November 29 this year.

What a shared plan actually limits

Shared hosting puts many accounts on one server and divides its capacity between them. The limits that matter in a rush are rarely on the price list.

• Processor time, the share of the server's computing your site may use.
• Memory, which every page needs while it is being put together.
• Simultaneous requests, how many visitors can be served at the same moment.
• Database connections, sometimes capped separately and reached first by busy stores.
• Bandwidth and storage, the figures usually advertised as unlimited.

The third usually runs out first. Each visitor holds a slot while the page is built, and once every slot is busy, the next visitor gets an error page, often numbered 503 or 508.

Unlimited, in hosting, describes storage and data transfer. The limits on processing and requests usually sit in the terms of service.

Why a crowd hits the limit

On a WordPress site, every page is normally built from scratch for every visitor: PHP runs, the database is queried, and the theme and plugins are assembled into a page.

That takes a fraction of a second, and a few hundred visits spread across a day barely register. The same few hundred in ten minutes queue for slots faster than the queue clears.

A heavy page makes it worse. A page builder and thirty plugins can turn a fraction of a second into several, and every one of those seconds holds a slot.

Caching does most of the work

Page caching keeps a finished copy of each page and sends it to the next visitor instead of building the page again, at a small fraction of the processing cost.

On a site that mostly describes services, nearly every page can be cached. On a store, product and category pages usually can, but carts, checkouts and account pages must be left out.

Set up carelessly, caching can show yesterday's prices or break a form, which is why it should be tested before the busy week, not during it.

A content delivery network for the heavy files

A content delivery network, or CDN, is a set of servers in many cities that keeps copies of your images, stylesheets and scripts and sends them from the one nearest each visitor.

Your own server then answers for the page itself and little else. Many CDNs can also hold whole pages and absorb a crowd before it reaches the server, and some hosting plans include one.

A worked example

A two-person hot sauce company in a Fraser Valley commercial kitchen sells through a small WordPress store on a basic shared plan, which suited its usual few dozen visitors a day.

Last November, a regional morning television show featured its gift sets. Within minutes the store was showing an error page about resource limits, and it stayed that way for most of an hour.

The cause was ordinary: every page built from scratch for every visitor, through a page builder and about thirty plugins, on a plan allowing only a handful of requests at once.

Over the winter, the store gained page caching with the cart and checkout excluded, compressed photographs served through a CDN, and eleven fewer plugins.

This month, the owner sent the host the dates of the Black Friday email and a local gift fair, and asked what the plan would allow on those days.

Make each visit cheaper

Every file a page asks for costs something under load, so a lighter page serves more people within the same limits.

Camera photographs of several megabytes, where a few hundred kilobytes would look the same, are the usual offender. Plugins that write every page view to the database are another.

Removing what nobody would miss is the cheapest extra capacity a site can get.

Talk to the host before the busy week

Hosts handle a predictable spike far better than a surprise, and most would rather hear about one in advance.

Ask what the plan's real limits are, what happens when they are reached, and whether the account can move to a larger plan for a week and back again.

Some hosts slow the site down, some show the error page, and a few suspend accounts that keep exceeding their limits. Better to learn which before the morning it matters.

Ask, too, where the control panel shows resource usage. A site that hits its limits on an ordinary Tuesday will not survive a busy Saturday.

When the plan itself is too small

A store whose checkout is busy every day, or a site that hits its limits on ordinary days with caching in place, has outgrown the plan.

The next step is a plan with resources reserved for the account. Sizing it from the usage history, not a guess, is part of what a web company that manages hosting does.

The counter-case

Most small business sites never see a crowd big enough to matter, and a trade whose visitors arrive a few at a time has little to gain from a CDN.

Caching also adds a moving part. A site showing live availability needs careful exclusions, and a spike from bots is a job for blocking, not serving.

But a business expecting press, running a big promotion or selling in December should know its plan's limits and have caching tested before the day.

Before the busy week

1. Find your plan's real limits in writing.
2. Check the resource usage page for recent hits.
3. Turn on page caching and test it.
4. Exclude the cart and checkout from the cache.
5. Serve images through a content delivery network.
6. Tell the host the dates of your promotions.
7. Ask who answers on a busy Saturday.

Step six costs nothing and changes the most. A host that knows the date can raise the limits and watch the server, instead of learning about the spike from an alarm.

Why shared plans are being repriced this year is covered in why hosting prices are changing this year.

Frequently asked questions

West Coast Media Solutions Inc. provides web design, web development, hosting, digital marketing, and business consulting to organisations across Canada, drawing on more than twenty-five years in the field.