| > what is "OpenJDK"? It is an open source project, comprising a codebase, a set of contributors, and various mailing lists, processes, and so on, just like any other open source project. The codebase is a continuation of the original Sun (later Oracle) JDK, now licensed under GPL 2 [1], with a linking exception that makes it fairly similar to the LGPL [2]. The contributors are mostly employees of big companies, with Oracle having by far the largest share. The OpenJDK project releases source code, but does not itself distribute binary builds. In this respect, it is like numerous other open source projects, such as GNU coreutils. Binary builds are made and distributed by operating system distributors (Red Hat, Debian, FreeBSD, etc), and also by various independent groups. As usual, each distributor may or may not add its own patches before building, and may or may not contribute these upstream. Eclipse Adoptium (formerly known as AdoptOpenJDK) [1] does not apply significant proprietary patches (just branding stuff), so it's a good place to get a plain vanilla OpenJDK build. Amazon's Corretto [4] in principle could contain whatever patches Amazon thinks are cool, but in practice usually just has a few backported bugfixes [5]. Azul's Core (formerly known as Zulu) has a bunch of patches (i couldn't find a list), and an option of commercial support) [6]. Oracle have a couple of builds, but you can ignore them. There are also builds from SAP, Bellsoft, and maybe others, but i have never really looked into them. Most people i know just use the AdoptOpenJDK / Adoptium builds, or whatever their distro gives them. EDIT: I got the Adoptium thing slightly wrong. AdoptOpenJDK made builds; those builds are now called Eclipse Temurin. Eclipse Adoptium is some sort of 'marketplace' where different builds are validated and made available. To me, this sounds like one of those Apache grand ideas that won't go anywhere, but we'll see. [1] https://github.com/openjdk/jdk/blob/master/LICENSE [2] https://opensource.stackexchange.com/questions/1410/what-is-... [3] https://adoptium.net/releases.html [4] https://aws.amazon.com/corretto/ [5] https://docs.aws.amazon.com/corretto/latest/corretto-11-ug/p... [6] https://www.azul.com/products/core/ |
But seriously, you don't see how this might be confusing? And what you've described is really only the tip of the iceberg. Who defines the specs? Who writes the compliance tests with the specs? Who runs those and certifies that implementations are compatible? What limits are there on entities that make builds, either on the patches they can apply (and still call it "Java") or the licenses they can adopt? What does "GPL with classpath exception" mean in the real world, that JDK-itself changes must be upstreamed, but linked applications need not be? What are the limits there?
The point is, getting an open source JDK binary is not easy, especially if you want to understand what you're getting. "OpenJDK" may exist as an OSS project, but I wouldn't call it typical. Not because it doesn't release binaries (although I just discovered it does, provided by Oracle for Windows/Linux only), but because of the license, the owner, and the owner's relationship to binary builders. The binaries you can get in practice have unknown additions from the vendor, and possible adjustments to the license (or is only Oracle allowed to make alternative licenses for an OpenJDK build?)
Compare java distribution to, say, node or python. Is it really fair to accuse someone who is confused of being an idiot?