Plesk 12.x / Linux :: Batch MySql Script Stopped

I've this terrible problem: on my site I start a script that executes a batch process that imports into the Mysql database a lot of products (texts and images). I'm monitoring the query process from Phpmyadmin>Status and I notice that after some minutes the number of queries decreases from ~900 to ~30, that means that the script is stopped! Then I check the error_log and infact there's this error:

[Thu Oct 02 17:09:34 2014] [warn] [client xxx.xxx.xxx.xxx] (104)Connection reset by peer: mod_fcgid: error reading data from FastCGI server
[Thu Oct 02 17:09:34 2014] [error] [client xxx.xxx.xxx.xxx] Premature end of script headers: insert_products.php

Some informations:
VPS server: 1 CPU; 40gb; RAM 1GB
OS: CentOS 6.5 (Final)
Plesk version: 12.0.18

What I tried via SSH console:

# /usr/local/psa/admin/bin/php_handlers_control --list
id: display name: version: type: cgi-bin: cli-bin: php.ini:

module 5.3.3 5.3.3 module /usr/bin/php-cgi /etc/php.ini
fastcgi 5.3.3 5.3.3 fastcgi /usr/bin/php-cgi /etc/php.ini
cgi 5.3.3 5.3.3 cgi /usr/bin/php-cgi /etc/php.ini
# /usr/bin/php-cgi -v

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