Bug#598347: hadoop: Better handling of HEAP_MEMORY_SIZE

[Thomas Koch]

Package: hadoop
Severity: normal

* Hadoop should not start, if the configured heap memory value is
  greater then the available memory size on the system

* Maybe one could build a shell script to adapt the memory size to a
  given percentage of the available memory, if no absolute size is
  given.

The shell code for both points could of course also be useful for other
java software on Debian.