now I can only set apache, to restart every hour in cron, but this method treats the symptoms rather than the root of the problem.
I am Ubuntu 16 + apache2 + php7.0 + mysql5.7

after running for a period of time, mysql hung up, and restart prompted insufficient memory. My top query found that apache2 and php occupied too much memory
. After I restarted apache, mysql can start normally, but it is estimated that it will hang up later. What is the situation?