> reference counts are exposed IIUC this is also true for PHP but HHVM has/had some interesting techniques to deal with it, like pairing up and cancelling out

> reference counts are exposed IIUC this is also true for PHP but HHVM has/had some interesting techniques to deal with it, like pairing up and cancelling out reference count operations, and bulk changing the reference count before taking a side exit or calling a C function.