Rails script terminating in between

I am trying to debug a rails script which is terminating in between, i am doing API calls and processing results in Batch format.

when my action is executed say its executed for 50 employees in a batch, for every employee i do a API call and process the response. But i observed that some times the script executes as expected but sometimes it terminates at different points, no specific pattern observed.

can anyone suggest as to what could be going wrong, how can u debug it further and reach the conclusion as to what could be going wrong.

Also i see that in the log the action is executed twice, i.e. the first time the script terminates abruptly it again makes an entry in the log not sure how that happens

for example i see http://ift.tt/2birYUL called twice in the log.