OK . I tried running the runcrawl.php via PuTTy SSH client and it indexed around 15,000 products and then gave following error:
PHP Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 14580497 bytes) in /var/www/vhosts/ZZZZ.com/subdomains/comparison/httpdocs/generator/pages/class.utils.inc.php(2) : eval()'d code on line 6
PHP Warning: Unknown: open(/var/lib/php/session/sess_d4633d7ba9cdb38103129a155e390286, O_RDWR) failed: Permission denied (13) in Unknown on line 0
PHP Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/var/lib/php/session) in Unknown on line 0