【Web-Apache】Worker MPM探索

Author：小怪獸Nikki 微博：@再見了小怪獸

去除http.conf中Include conf/extra/httpd-mpm.conf前的#，以使httpd-mpm.conf中的配置生效。

#Server-pool management (MPM specific)
Include conf/extra/httpd-mpm.conf

一、Apache的默認情況

<IfModule mpm_worker_module>
StartServers             3
 MinSpareThreads         75
MaxSpareThreads        250
ThreadsPerChild         25
MaxRequestWorkers      400
MaxConnectionsPerChild   0
</IfModule>

由此可見，Apache在啓動時，按照默認StartServers啓動3個子進程，並且由於已經符合最小空閒進程，故不再變化。

二、startServers*ThreadsPerChild < MinSpareThreads，MinSpareTreads爲ThreadsPerChild的整數倍：

<IfModule mpm_worker_module>
    StartServers             3
    MinSpareThreads         100
    MaxSpareThreads        250
    ThreadsPerChild         25
    MaxRequestWorkers      400
    MaxConnectionsPerChild   0
</IfModule>

[root@testhadoop-slave1 extra]# ps -ef|grep httpd
root     43900     1  0 03:37 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
daemon   43903 43900  0 03:37 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
daemon   43904 43900  0 03:37 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
daemon   43911 43900  0 03:37 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
daemon   44087 43900  0 03:37 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
root     45907 20322  0 03:37 pts/0    00:00:00 grep httpd

由於3個初始的子進程共提供75個線程，故不滿足100個最小空閒線程數的要求，所以apache新啓動一個子進程來提供額外的線程.

三、startServers*ThreadsPerChild < MinSpareThreads，MinSpareTreads爲ThreadsPerChild的非整數倍：

<IfModule mpm_worker_module>
    StartServers             3
    MinSpareThreads         90
    MaxSpareThreads        250
    ThreadsPerChild         25
    MaxRequestWorkers      400
    MaxConnectionsPerChild   0
</IfModule>

[root@testhadoop-slave1 extra]# ps -ef|grep httpd
root     38933     1  0 03:46 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
daemon   38937 38933  0 03:46 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
daemon   38938 38933  0 03:46 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
daemon   38942 38933  0 03:46 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
daemon   39112 38933  0 03:46 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start

[root@testhadoop-slave1 bin]# sh jingjingtest/test.sh
38937:26
38938:26
38942:26
38937:26
38938:26
38942:26
39112:26

由此可見apache在啓動3個子進程後又啓動一個子進程，但是並沒有給新的子進程新建90-25*3=15個線程，而是也生成26個線程（其中一個爲監控線程），新子進程的線程數爲：ThreadsPerChild個。

四、startServers*ThreadsPerChild > MinSpareThreads

<IfModule mpm_worker_module>
    StartServers             3
    MinSpareThreads         10
    MaxSpareThreads        250
    ThreadsPerChild         25
    MaxRequestWorkers      400
    MaxConnectionsPerChild   0
</IfModule>

[root@testhadoop-slave1 extra]# ps -ef|grep httpd
root     21985     1  0 03:53 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
daemon   21987 21985  0 03:53 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
daemon   21988 21985  0 03:53 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
daemon   21992 21985  0 03:53 ?        00:00:00 /data2/irunner9001/lamp/apache//bin/httpd -k start
root     23846 20322  0 03:53 pts/0    00:00:00 grep httpd
[root@testhadoop-slave1 bin]# sh jingjingtest/test.sh
21987:26
21988:26
21992:26
21987:26
21988:26
21992:26
21987:26
21988:26
21992:26
21987:26
21988:26
21992:26

由此可見，當初始啓動的線程數已經滿足最小空閒線程，而沒有超過最大空閒線程，則不會再清除線程。

五、有請求時，已有線程數-請求數 < 最小空閒線程：

<IfModule mpm_worker_module>
    StartServers             3
    MinSpareThreads         75
    MaxSpareThreads        250
    ThreadsPerChild         25
    MaxRequestWorkers      400
    MaxConnectionsPerChild   0
</IfModule>

發送請求：

ab -n 10000 -c 10  http://10.210.228.50:9001/

各子進程線程情況：
---
19202:26
19203:26
19210:26
---
19202:26
19203:26
19210:26
---
19202:26
19203:26
19210:26
20082:26
---
19202:26
19203:26
19210:26
20082:26
---
19202:26
19203:26
19210:26
20082:26
---
19202:26
19203:26
19210:26
20082:26
---
19202:26
19203:26
19210:26
20082:26
---
19202:26
19203:26
19210:26
20082:26
---
19202:26
19203:26
19210:26
20082:26

由此可以看出，初始有3個子進程，共有3*25=75個線程，當有10個請求到來，存在空閒線程不足minSpareThread個，則新啓動一個子進程。