Timeout error and 500 error while updating huge xml file

What happened for you to see this error, what is the cause of this error, how can you solve it immediately, and how can ensure that it won’t happen again?

 What happened?The allowed memory size is not a Joomla error, it’s a PHP error. It happens when PHP needs more memory to run your scripts, but is unable to allocate more memory because its available memory limited to 128 MB (128 MB = 134217728 bytes – note that 128 MB is just an example, your memory limit might be smaller or higher). By default, the memory limitation is determined in the php.ini file.What is the cause of this problem?Joomla is a memory hungry CMS, and sometimes it takes a lot of memory to process a page, especially if that page contains many 3rd party extensions that are also heavy on the memory. On a recent job, the customer was using an extension that was creating an array out of a 200,000 row MySQL table. The extension author was not aware that his extension will be used to process such a large amount of data, and thus has not optimized it. Naturally, our customer was running into the “Allowed memory size…” error every time the extension ran.How can this problem be solved immediately?The fastest and most expedient way to solve this problem is by increasing the PHP memory limit. The PHP memory limit can be increased in one of the following 4 ways:

1. Increasing the PHP memory limit at the server level (global php.ini): This can only be done if your website is running on a dedicated server or on a VPS. What you do is that you edit the php.ini file and change the memory_limit value to a larger amount. Once you do that, you will need to restart Apache in order for the changes to take effect.
2. Increasing the PHP memory limit at the application level (local.php.ini): This can be done by just making a copy of your global php.ini, changing the memory_limit value to a larger amount, and then uploading the modified copy to the root directory of your Joomla website (e.g. /public_html/ or /public_html/yourjoomlawebsite.com/). (You will need the server administrator to send you the global copy of php.ini in order to do this.)
3. Increasing the PHP memory limit at the .htaccess level: This can be done by adding the below line to the beginning of your .htaccess file (which is located in the root directory of your website):

   php_value memory_limit 512M

   The above code will increase the PHP memory limit to 512 megabytes.
4. Increasing the PHP memory limit at the code level: This can be done by adding the following line to your beginning of your index.php (which is located in the root directory of your Joomla website – do not add it to your configuration.php, because any change in your configuration settings will overwrite your configuration.php and your custom changes will be lost):

   ini_set('memory_limit', '512M');

Now what is the best way to increase the memory limit? We believe the best way to increase your memory limit is either by doing it in the index.php file or in the .htaccess file. This will ensure that if you decide to switch hosting companies, then your PHP memory settings will remain the same.Using Ro csvi component you will have to do a tricky modification.
Add the  following line