What is for PHP_ZTS predefined constant in PHP?

Question

There is a predefined constant PHP_ZTS available from PHP 5.2.7, but there is no documentation for it in the manual.

Can anyone explain what's its purpose?

Answer 1

PHP_ZTS is predefined constant which returns whether Zend Thread Safety (ZTS) is enabled or not.

PHP_ZTS (return value of "0" (false) indicates compiled php is non thead safe)

Some extensions need ZTS enabled to work properly with PHP; it's enabled using the option:

--enable-maintainer-zts

at PHP build time.