[tex-live] Tlmgr closing takes fairly long

[Paulo Roberto Massa Cereda]

'ello! :)

[Simon May]
 > There are no “standard classes that are not distributed with JRE but
 > JDK is required”. Java has a standard library, required to be
 > implemented by all conforming implementations (like the C standard
 > library for the C language) and which is distributed in what is
 > called the JRE, or Java Runtime Environment. The JDK (Java
 > Development Kit) is for development, as the name suggests. Any
 > program relying specifically on the presence of a JDK is doing
 > something seriously wrong.

It is worth mentioning that some Linux distros deliberately separate 
Java components in order to avoid unnecessary bindings. In Fedora, 
there's a headless version:

[paulo at cambridge ~] $ rpm -qa | grep headless
java-1.8.0-openjdk-headless-1.8.0.91-6.b14.fc23.x86_64

This package has no graphical components. As the name indicates, it is 
used in environments where there is no need for a GUI (there are no X11 
bindings). This is my Java setup:

[paulo at cambridge ~] $ rpm -qa | grep openjdk
java-1.8.0-openjdk-1.8.0.91-6.b14.fc23.x86_64
java-1.8.0-openjdk-headless-1.8.0.91-6.b14.fc23.x86_64
java-1.8.0-openjdk-devel-1.8.0.91-6.b14.fc23.x86_64

The first two ensure normal execution of Java programs, including the 
ones with GUI features. The last one regards development and it is not 
needed for the average user.

About execution, as time goes by, each version gets enhanced (or 
bloated, pick the term you like) with new features. In general, you can 
run older code in newer JVMs, but the opposite is not always true. Also, 
bytecode compatibility does not always guarantee proper execution in 
older JVMs, but that's another chapter. :)