rlm_perl CLONE under freeradius 3.x

hi: I am writing rlm_perl script under freeradius 3.0.4 which comes with RHEL 7.1. and I am confused about how thread working with rlm_perl. according to the old message at email list, if I want every radius thread to have their own unique variable, I should put the variable at "CLONE" function like below: our ($var); CLONE { $var = ''; } but after testing, I found even if the variable is not put at the CLONE function, they are still unique to each thread. may I ask what is the correct method to make global thread shared variable and thread unique variable under rlm_perl ? Regards, tbskyd