For longer php scripts: opcache_reset() will obtain a lock and it will reset the cache only after the script has ended, after which the lock is released.
Calling opcache_reset() multiple times or any other opcache manipulation method, like opcache_invalidate(), after calling opcache_reset() in a single script is not useful: while opcache_reset() holds the lock, other opcache methods will return false and they will have zero effect on the cache.
Although the opcache manipulation methods have no effect during this lock, opcache does recache scripts corresponding to the opcache.revalidate_freq setting, provided that opcache.validate_timestamps is switched on.
To keep the cache up to date, use opcache_invalidate() when modifying single php files. Use opcache_reset() for bigger changes and only at the end of a php script.