- Default:
OFF - Values:
ON|OFF
Better known as Zend Thread Safety (ZTS), this feature allows PHP to handle multiple threads safely in web server environments that require thread-safe execution.
For instance, if Apache uses PHP with a threaded Multi-Processing Module (MPM)
or on Windows, PHP must be configured and built with PHP_THREAD_SAFETY set to
ON. Thread safety is also enabled automatically during configuration if a
threaded Apache is detected on the system.
Since enabling thread safety adds complexity to PHP usage and installation due to separate builds of PHP SAPIs and extensions, it is recommended to enable it only when necessary. At the time of writing, the non-thread-safe (NTS) PHP build may be a better choice for most environments.