This post talks about a better way to retry failed operations in Java using classes in Spring.

Requirements

Stuff used in this post.

• Spring Core 4.2.1.RELEASE

Retry Codes in Vanilla Java

Off the top of our head, how would we code something that does the following?

• retries a failed operation n  times
• each retry, the amount of time to wait before next try increases
• stops retrying an operation after n  times

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Here’s mine:

Output:

That’s ugly!

Let’s try a better way at doing this.

Back Off

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Spring Core has these related interfaces and classes:

• Interfaces
  • org.springframework.util.backoff.BackOff
  • org.springframework.util.backoff.BackOfExecution
• Classes
  • org.springframework.util.backoff.ExponentialBackOff
    • Implementation of BackOff  that increases the back off period for each retry attempt. When the interval has reached the max interval, it is no longer increased. Stops retrying once the max elapsed time has been reached.
  • org.springframework.util.backoff.FixedBackOff
    • A simple BackOff  implementation that provides a fixed interval between two attempts and a maximum number of retries.

They allow us to create the wait-and-retry functionality in a more elegant way.

Using FixedBackOff

These are sample codes for FixedBackOff.

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Output:

Using ExponentialBackOff

These are codes for ExponentialBackOff.

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Output:

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