Random 500 internal server error loading json data via ajax in Codeigniter project

问题

I am loading json data that is displayed in graph via AJAX aas implemented by the c3js library (http://c3js.org).

The function that

site = 'http://example.co.ke/';
   var debits_ = c3.generate({
    bindto: '#account-debits',
    data: {
            x: 'time',
            xFormat: formart_,
            type:"area", 
            colors: {
                credit_type: '#1ABB9C'
            },
            url: site+"dashboard/credits_data/db/"+log_data,
            mimeType: 'json'
        });

I am making about 5 to 7 similar requests at the same time.

I however get random 500 Internal server error messages. (requests work and show data or give error randomly every time I make a new request)

No error

Error

Error

Could the issue be caused by CodeIgniter session? What is a possible solution? It works well on localhost without any error but on a shared server it fails.

来源：https://stackoverflow.com/questions/32632735/random-500-internal-server-error-loading-json-data-via-ajax-in-codeigniter-proje