測試環境：Ubuntu 20.04 LTS
Apache version：apache2 -v
Server version: Apache/2.4.41 (Ubuntu)
Server built: 2021-10-14T16:24:43
default 配置下啟動apache server帶起兩個process以及(25+1) * 2個thread
ps aux | grep apache | grep www-data | wc -l
2
ps -efL | grep apache2 | grep www-data | wc -l
54
同時間點的request越高所需要的thread也就越多，但防禦上比來就是可以針對同一IP多去進行rate-limit
Apache配置
<IfModule mpm_event_module>
StartServers 2
MinSpareThreads 25
MaxSpareThreads 75
# ServerLimit default 32 max 20000
ServerLimit 32
threadlimit 64
ThreadsPerChild 25
MaxRequestWorkers 1500
MaxConnectionsPerChild 0
</IfModule>
理論最高thread : 32 * (25+1) = 832 Max RequestWorkers是針對同一IP進行設定正常設定不應該超過最高thread數量這邊測試需求暫時不管
以下利用slowhttptest進行測試了解mpm_event底下的thread運作
case 1.
測試指令
slowhttptest -c 2000 -X -w 512 -y 1024 -n 5 -z 32 -k 3 -r 100 -u http://192.168.0.27 -p 3
root@test-Standard-PC:~# ps -aux | grep apache2 | grep www-data | wc -l
31
root@test-Standard-PC:~# ps -efL | grep apache2 | grep www-data | wc -l
837
該數字包含31個process，實際計算 31 * (25+1) + 31 = 837
case 2.
測試指令
slowhttptest -c 2000 -X -w 512 -y 1024 -n 5 -z 32 -k 3 -r 40 -u http://192.168.0.27 -p 3
ps -aux | grep apache2 | grep www-data | wc -l
27
root@test-Standard-PC:~# ps -efL | grep apache2 | grep www-data | wc -l
729
實際計算 27 * ( 25 +1) + 27 = 729
case 3.
測試指令
slowhttptest -c 2000 -X -w 512 -y 1024 -n 5 -z 32 -k 3 -r 200 -u http://192.168.0.27 -p 3
ps -aux | grep apache2 | grep www-data | wc -l
32
root@test-Standard-PC:~# ps -efL | grep apache2 | grep www-data | wc -l
864
此次測試直接把apache server打垮看到最高thread=864-32=832 = ServerLimit * (ThreadsPerChild+1)
Apache配置
<IfModule mpm_event_module>
StartServers 2
MinSpareThreads 25
MaxSpareThreads 75
# ServerLimit default 32 max 20000
ServerLimit 32
threadlimit 64
ThreadsPerChild 25
MaxRequestWorkers 200
MaxConnectionsPerChild 0
</IfModule>
理論最高thread : 32 * (25+1) = 832
以下測試MaxRequestWorkers不同設定值時對應的thread數量
測試指令
slowhttptest -c 2000 -X -w 512 -y 1024 -n 5 -z 32 -k 3 -r 100 -u http://192.168.0.27 -p 3
Case 1.
MaxRequestWorkers 200
root@test-Standard-PC:~# ps -aux | grep apache2 | grep www-data | wc -l
9
root@test-Standard-PC:~# ps -efL | grep apache2 | grep www-data | wc -l
243 = (9 * (25+1)) + 9
Case 2.
MaxRequestWorkers 300
ps aux | grep apache2 | grep www-data | wc -l
12
root@test-Standard-PC:~# ps -efL | grep apache2 | grep www-data | wc -l
324 = (12 * (25+1)) + 12
可知 MaxRequestWorkers 由於啟動一個新process 會同時代起MinSpareThreads個數量之thread，因此實際看到thread會是 child process (ThreadsPerChild+1) > MaxRequestWorkers > (child process-1) (ThreadsPerChild+1)
