502 Gateway timeout while uploading gif image

I have install imagick extension on my server and uses its function while uploading GIF images.
I have created custom toolkit for this and alter the image scale effect to add imagick extension function for gif images. For jpeg/jpg images I have used GD library function. On conditional basis I have used GD and my custom toolkit.

But for some GIF images I am getting 502 gateway timeout error. When I have checked server error logs and found following errors:

018/08/01 04:53:47 [error] 15450#0: *508865 recv() failed (104: Connection reset by peer) while reading response header from upstream

2018/08/01 06:28:34 [error] 15450#0: *509548 upstream timed out (110: Connection timed out) while reading response header from upstream

2018/08/01 06:32:52 [error] 15451#0: *509581 recv() failed (104: Connection reset by peer) while reading response header from upstream

The gif image is taking full RAM while uploading on server. I am attaching the gif image which is creating issue.