A strange problem arises when high concurrency generates QR Code

[wangyouw]

this is my problem detail ,can somebody help?
In the PHP error_log，Intermittent occurrence of warning,like this ：
1.imagecreatefromstring(): gd-png: fatal libpng error: [00][00][00][00]: invalid chunk type
2.imagecreatefromstring(): gd-png: fatal libpng error: Read Error: truncated data
3.imagecreatefromstring(): gd-png: fatal libpng error: PLTE: CRC error
4.imagecreatefromstring(): gd warning: one parameter to a memory allocation multiplication is negative or zero
5.imagecreatefromstring(): gd-png: fatal libpng error: IHDR: CRC error

1.Server environment（centos7.2+php7.1 + nginx+gd2.1.0+libpng1.5.13+zlib1.2.7）
2.QPS is somewhere around 100 to 500
3.code like this:
QRcode::png($url, $file_path, $errorCorrectionLevel, $matrixPointSize, $margin);
$QR = imagecreatefromstring(file_get_contents($file_path));

I wonder if the file_put_content need a lock in phpqrcode project ?
This problem has been bothering me for a few days，Jesus，I'm crazy..... help