add concurrency support in java

Signed-off-by: Mattias Andrée <maandree@operamail.com>
split python3 version into two files

Signed-off-by: Mattias Andrée <maandree@operamail.com>
split python2 version into two files

Signed-off-by: Mattias Andrée <maandree@operamail.com>