pht requires a ZTS (Zend Thread Safety) version of
PHP. Currently, only PHP 7.2 is supported. Support for PHP 7.3
(which will be released at the end of 2018) will be coming soon.
PHP 7.0 and 7.1 are unsafe to support, due to race conditions in
pht should be compatible for any OS with the
pthread library (or pthread-win32 library, which is for