WordPress Import Plugin dies abruptly

Ok so I have created a WordPress plugin which imports a bunch of CSV entries and converts them into WordPress posts. The script sets memory limit to -1 and maxexecutiontime to 0. I am trying to run this on a 1024 MB node provided by Linode. The node has VirtualMin installed and PHP is configured to run as FCGId. I have added the following to /etc/apache2/mods-available/fcgid.conf:

FcgidBusyTimeout 604800

FcgidIdleTimeout 999999999

FcgidMaxRequestsPerProcess 999999999

MaxRequestsPerProcess 999999999

IdleTimeout 999999999999999

FcgidMaxRequestsPerProcess 999999999

FcgidIOTimeout 999999999

I am trying to import a CSV file with over 20k entries but the script dies after importing around 4k entries.

I would like to know if whether this could be because of a setting related to MySQL/Apache/PHP or is it related to the amount of resources available like memory etc?

When the script dies, the error_log makes no mention of anything related to this.

The script runs for around 3 or 4 minutes before it dies but I know this isn't related to the amount of time it's allotted because I have successfully run a test script I created to run for 15 minutes in which it sleeps every second and then writes to a file. It ran fine without any problem.