Bug #87652 InnoDB: Warning: a long semaphore wait:
Submitted: 4 Sep 2017 9:35 Modified: 4 Sep 2017 19:40
Reporter: Dominik Müller Email Updates:
Status: Can't repeat Impact on me:
None 
Category:MySQL Server: InnoDB storage engine Severity:S1 (Critical)
Version:mysql Ver 14.14 Distrib 5.5.57, for deb OS:Debian (Jessie)
Assigned to: MySQL Verification Team CPU Architecture:Any
Tags: innodb semaphore crashs

File: Maximum allowed size is 50MB.
Description:
Privacy:

If the data you need to attach is more than 50MB, you should create a compressed archive of the data, split it to 50MB chunks, and upload each of them as a separate attachment.

To split a large file: