Questions 1 and 2

Signed-off-by: Thiago de Barros Lacerda <thiago.lacerda@openbossa.org>
Using ReentrantLock

Signed-off-by: Thiago de Barros Lacerda <thiagotbl@gmail.com>
One lock per counter

Signed-off-by: Thiago de Barros Lacerda <thiagotbl@gmail.com>