PHPExcel fails on a heavy file import - php

Question

I am trying to import excel files (xlsx) using PHPExcel library and store the data in a database. Following is my code:
require_once $_SERVER['DOCUMENT_ROOT']."/application/views/subfolder/PHPExcel/Classes/PHPExcel/IOFactory.php";
$file_name = $_FILES['controlname']['tmp_name'];
$ext = pathinfo($file_name, PATHINFO_EXTENSION);
$inputFileName = $file_name;
$inputFileType = PHPExcel_IOFactory::identify($inputFileName);
$objReader = PHPExcel_IOFactory::createReader($inputFileType);
$objPHPExcel = $objReader->load($inputFileName);
$objPHPExcel->setActiveSheetIndex(0);
$sheet = $objPHPExcel->getActiveSheet();
When I import a 1MB+ file having more than 1000 records, the code fails without returning any error with a strange behavior. However when I reupload that file by splitting it into multiple excels such that each excel contains only 1000 records, the same code works successfully.
To test, I tried echoing some message before and after the following line:
$objPHPExcel = $objReader->load($inputFileName);
The message echoed before this line is printed, but the message written after this line does not work.
In order to allow heavy loads I have made settings of ini in MBs as well as GBs, but nothing works.
ini_set("pcre.backtrack_limit", "100000000");
ini_set("max_allowed_packet ", "2G");
ini_set("max_execution_time ", "20000");
ini_set('max_input_time','20000');
ini_set('memory_limit', '2G');
ini_set('upload_max_filesize','20M');
ini_set('post_max_size', '2G');
set_time_limit(0);