Posting checkbox value via ajax

Before marking it as duplicate ,please read my concern

I have a ajax which post checked checkbox serialized data.I have around 40k checkboxes selected .But when i dumping the serialized data count i am only getting around 20k count.Am i missing anything

var investors=investorDatatable.$("input[name='investors[]']:checked").serializeArray();
    console.log(investorDatatable.$("input[name='investors[]']:checked").length);
    console.log(investors);
    if(investors)
    {
    $('#loader').show();
    $.ajax({
        url: deleteMultipleUrl,
        type: 'POST',
        data:  investors,
        dataType: 'json',
        success: function (data) {
            if (data['status'] = 'success') {
    }

first console ouput is 39862 second console ouput is an array of the 39862 records.

But when i dump the count in the controller it shows 20001