Differences Amazon Corretto and OpenJDK

Question

What are the differences between Amazon Corretto and OpenJDK (and Oracle\'s OpenJDK - but there is already a ticket about this)? Corretto is a OpenJDK version 8 implementation.

Answer 1

The patches applied are listed in the following pages:

• https://docs.aws.amazon.com/corretto/latest/corretto-8-ug/patches.html
• https://docs.aws.amazon.com/corretto/latest/corretto-8-ug/change-log.html

I am not copying over as the list is going to grow over time, but the focus seems to be bug fixes and performance fixes patches and backports.

Answer 2

From Amazon's description:

"Patches and improvements in Corretto enable Amazon to address high-scale, real-world service concerns, meeting heavy performance and scalability demands. We’re making these available to customers with no-cost, long-term support, with quarterly updates including bug fixes and security patches. AWS will also provide urgent fixes to customers outside of the quarterly schedule"

So Corretto has tweaks that are specific to performance (e.g. for server or cloud applications), and also additional bug fixes that users can take advantage of that aren't necessarily in OpenJDK proper yet. Also with this Amazon is offering proper LTS support of their build, as other commercial companies are starting to do for the JDK (Oracle and Azul come to mind, as well as others).

Answer 3

A very detailed presentation about Amazon Corretto by James Gosling can be found here

Answer 4

I can tell you we have found a few subtle differences. We have not identified the root cause of the differences but we do know that Jasper reports generated with Corretto have minor differences in some of the offset numbers, such as leadingOffset="-2.9667969" in corretto vs "-2.737793" in the Oracle JVM. There is no visual difference but it led to failure in golden master tests. Additionally some very old deprecated tools such as text to tiff rendering are not included. Other than that we have converted many projects over to Corretto without issue.