mysql restart due to low memory on the server,may have DoS and DDoS problem how to fix it?

Dear Sir,
mysql restart due to low memory on the server,may have DoS and DDoS problem
how to fix it?

Many Thanks!

http://24hws.com/ddos.txt
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some times there is enaugh https traffic that take all memory and mysql crash
today again your mysql restart due to low memory on your server
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these are some kernal errors
Oct 12 06:23:09 ip-172-31-9-209 kernel: [84153.878914] httpd invoked oom-killer: gfp_mask=0x24280ca, order=0, oom_score_adj=0
Oct 12 06:23:09 ip-172-31-9-209 kernel: [84153.885184] httpd cpuset=/ mems_allowed=0
Oct 12 06:23:09 ip-172-31-9-209 kernel: [84153.888696] CPU: 0 PID: 5510 Comm: httpd Tainted: G E 4.4.19-29.55.amzn1.x86_64 #1
Oct 12 06:23:09 ip-172-31-9-209 kernel: [84153.892682] Hardware name: Xen HVM domU, BIOS 4.2.amazon 05/12/2016
Oct 12 06:23:09 ip-172-31-9-209 kernel: [84153.892682] 0000000000000000 ffff8800375b7b58 ffffffff812c958f ffff8800375b7d40
Oct 12 06:23:09 ip-172-31-9-209 kernel: [84153.892682] 0000000000000000 ffff8800375b7be8 ffffffff811ce76d ffff8803cffd3b30
Oct 12 06:23:09 ip-172-31-9-209 kernel: [84153.892682] ffffffff810b2d91 0000000000000000 0000000000000010 ffffffff817d0fe9