Instant start

Most of the time your app is asleep, and when someone arrives a copy of it starts. Most apps start in a second or two. A Java app, such as one built with Spring Boot, takes several seconds, so the first visitor after a quiet spell waits.

Instant start saves your app, already started, each time you deploy. Every new copy then starts from that save instead of starting from nothing. A Spring app's first visitor waited about 6 seconds without it and about 1 second with it.

It is for Java apps. Other apps already start quickly.

What it costs

Like busy hours, it costs money by existing, so the price is shown before you turn it on. It is sold at cost: you pay what Amazon charges us to keep the saved copy, plus the card fee on the credit that pays for it. We make nothing on it.

For a Java app with 2,048 MB of memory, the usual size:

• $8.73 a month while it is on, charged by the hour.
• About 4 cents for each deploy. Amazon charges every new save for at least its first three hours, even if you deploy again sooner, so each deploy pays those at once.
• About 0.03 cents each time a new copy of the app starts from the save.

No plan includes instant start. It is paid from your Uarpie credit as it is used, and it counts toward your spending limit. So it needs three things: a paid plan, credit above $0, and a spending limit above $0.

If the credit runs out, or the month's use above your plan reaches your spending limit, your apps pause. Nothing of yours is deleted. While an app is paused its saved copy is let go of, so it costs nothing; instant start stays on, and your next deploy saves a new one. Apps come back at the start of the next month, or straight away when you add credit or raise the limit.

How to turn it on

Tell your AI: "Turn on instant start for my app." It tells you what that costs a month, and asks before turning it on. Or open the app's page in the dashboard and choose Start in about a second, which shows the same price.

The change goes out as a new version of your app. That version, and every deploy after it, takes about a minute longer, while the save is made.

Turning it off is always allowed, and stops the charge from the next version on.

Things to know

• Busy hours and instant start cannot be on together. Busy hours keep copies of your app awake, and a saved copy cannot be kept awake. Pick one: busy hours for known busy moments, instant start for any time.
• Every copy makes its own random numbers. Copies started from one save begin with the same memory. Uarpie makes sure Java's secure random numbers, session ids and plain random numbers differ in every copy. A random value your own code makes once at start and keeps, such as an id it gives itself, is the same in every copy, so make those when they are first needed instead.
• Database connections are made again. Connections your app had open when it was saved may be closed in a new copy. The usual Java connection pool, HikariCP, notices and opens new ones.