Do I need to restart Apache after changing the php.ini file?

Depends, actually. Depends on how you use php inside that webserver:

• using php a module: you have to restart the server process
• using php as cgi backend: you do not have to restart the server process
• using php fastcgi: not sure, actually... (restarting is on the safe side, though)
• using PHP-FPM: you have to restart the fpm server process to prevent inconsistencies

On Debian 8 I had to restart PHP-FPM (and Apache) The above answers are correct, but here are the commands so you won't have to googling them.

Restart Apache :

/etc/init.d/apache2 restart

Restart php5-fpm :

sudo service php5-fpm restart

That depends on the SAPI you're using. If you're using PHP as an Apache module for example, you need to restart apache so that the php.ini values take effect.

If you're using FCGI, you need to restart the FCGI daemon for the PHP script that you want to see the values changed. Compare with

• Trouble changing upload_max_filesize on nginx