Wordpress What does this look like to you? admin-ajax.php loads

Screenshot: Screenshot by Lightshot - happens everyday at the same exact time and for the life of me, I can not figure out what is causing this spike. The CPU load shoots to 30+ and lasts for 15-20 minutes and everything goes back to normal again. My first thought was a plugin so I disabled them all for 24 hours and it still happen - I monitored traffic with How to sniff HTTP traffic from the command line on Linux - Xmodulo and it was moving extremely fast and I monitored with How to sniff HTTP traffic from the command line on Linux - Xmodulo and it said the file being hit the hardest was admin-ajax.php so I disabled that from within functions.php and it still didn't do anything

Think DDoS maybe? But why such a short burst and then just die and go back to normal. A DDoS is usually continuous until it crashes the VPS but this VPS doesn't crash even under a 30+ load average - It slows down to a crawl but it doesn't crash.

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Did that and didn't work - Then I edited the functions.php file and added:

I wanted to completely stop it and the plugin only "controls" it but even code didn't work

 

Bingo! Brian, the person who posted that post referenced above is a good friend, I even read this post awhile ago!

Screenshot by Lightshot

The plugin "Thrive Leads" was the issue - Disabling it did nothing - Deleting it did the trick.

 

Couldn't possibly be an issue with Admin-Ajax. Happened 3 times tonight - VPS was down 3 times and all 3 times looked exactly the same as the others.
So I decided to break out the trusted Siege tool and do a little bombing myself on this site and see if I can come close to replicating what is happening..

Test run:

Code:

Lifting the server siege...      done.

Transactions:                  53653 hits
Availability:                 100.00 %
Elapsed time:                 599.82 secs
Data transferred:            1057.02 MB
Response time:                  7.82 secs
Transaction rate:              89.45 trans/sec
Throughput:                     1.76 MB/sec
Concurrency:                  699.26
Successful transactions:       52940
Failed transactions:               1
Longest transaction:           25.26
Shortest transaction:           0.14

The VPS never failed, Never went down at all. The CPU reached 30+ but still didn't fail. I think im going to enable DDoS protection on this VPS...

53K hits in 10 minutes without a break and never failed - I give that a ( using Redis )