phpexcelにビッグデータをインポートする際のメモリオーバーフローの解決策は何ですか?

PHPExcel_CachedObjectStorageFactory::cache_in_memory_serialized;

PHPExcel_CachedObjectStorageFactory::cache_in_memory_gzip;

PHPExcel_CachedObjectStorageFactory::cache_to_discISAM;

PHPExcel_CachedObjectStorageFactory::cache_to_phpTemp;

PHPExcel_CachedObjectStorageFactory::cache_to_memcache；

$cacheMethod = PHPExcel_CachedObjectStorageFactory::cache_to_memcache;  
$cacheSettings = array( 'memcacheServer'  => 'localhost',  
     'memcachePort'    => 11211,  
     'cacheTime'       => 600  
);  
PHPExcel_Settings::setCacheStorageMethod($cacheMethod, $cacheSettings);

require_once APPPATH .'third_party/PHPExcel/PHPExcel.php';
        
$cacheMethod = PHPExcel_CachedObjectStorageFactory::cache_to_phpTemp;
$cacheSettings = array('memoryCacheSize'=>'16MB');
PHPExcel_Settings::setCacheStorageMethod($cacheMethod, $cacheSettings);
$objPHPExcel = new PHPExcel();