OpenJDK is a version of JDK released under GPL (with GNU Classpath exception) open source license. OpenJDK comes with various improvements over the classical Oracle's JDK which often makes the OpenJDK much less usable than the original. One of the problems is the modified launcher parameters as described in Virtualization page. Instead of being helpful, it just makes the whole system unusable. However, at least the system starts.
$ java Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine.
Why? The system has a lot of resources, so where is the problem? It turned out that the workaround is easy. Just to limit the number of available memory (this by itself is ridiculous, but it shows that allowing virtualization is not the primary driver for evolution of Java technology):
$ java -mx64M Usage: java [-options] class [args...] (to execute a class) or java [-options] -jar jarfile [args...] (to execute a jar file)
The question however is: How to modify each JDK utility (jar, javac, javadoc, etc.) to use this changed setting? Usual Unix style is to locate /etc/java.conf and tweak it. But of course Java has multiplatform, not Unix roots, so no such configuration file exists, as far as I can tell. I thought configuring the default options for all Java processes is impossible. However today I realized that
$ java -client
works too fine as well. From that moment it was just a small step to symlink the server directory inside the JDK installation to client:
$ cd jre/lib/i386/ $ mv server/ server.bak/ $ ln -s client server
Now I can use all the JDK functionality without problems. However it took me a while to get there. No surprise nobody offers Java in virtualized environments, when it is so hard to set it up (and PHP is instantly ready).
Jan 30, 2014 update
I've run into the same problem again after switching to new CentOS 6. This time it is amd64 bit virtualized environment and to make things worse, the 64-bit Java does not have the client mode anymore!
Well, it is not documented, but there is:
_JAVA_OPTIONS="-Xmx64M -XX:MaxPermSize=32M" export _JAVA_OPTIONS
Still I wonder. Am I really the only person on a planet to run into such issues?