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This article introduces the relevant knowledge of "how to make the website faster". In the operation of actual cases, many people will encounter such a dilemma. Then let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

The performance improvements in Apache 2.0 are the most attractive. On Unix systems that support POSIX threads, Apache can run in a mixed mode of multi-process and multi-thread through different MPM to enhance the scalable performance of some configurations. A lot of optimizations have been made to improve processing power and scalability compared to Apache 1.3 and 2.0, and most of the improvements take effect by default. But at compile and run time, 2.0 also has many options that can significantly improve performance.

MPM (Multi-Processing Modules) is the core feature that affects the performance of Apache2.0.

It is no exaggeration to say that the introduction of MPM is the most important change in Apache 2.0. As you all know, Apache is based on modular design, and Apache 2.0 extends modular design to the most basic functions of Web servers. The server is loaded with a multiprocessing module, which is responsible for binding native network ports, accepting requests, and dispatching child processes to process requests. Extended modular design has two important benefits:

◆ Apache can support multiple operating systems more succinctly and efficiently

The ◆ server can be customized according to the special needs of the site.

At the user level, MPM looks very similar to other Apache modules. The main difference is that only one MPM can be loaded into the server at any one time.

Using Linux RedHat AS3 as the platform, the following demonstrates how to specify MPM in Apache 2.0.

# wget http://archive.apache.org/dist/httpd/httpd-2.0.52.tar.bz2

# tar jxvf httpd-2.0.52.tar.bz2

# cd httpd-2.0.52

#. / configure-- help | grep mpm

The display is as follows:

-- with-mpm=MPM Choose the process model for Apache to use. MPM= {beos | worker | prefork | mpmt_os2 | perchild | leader | threadpool}

The above operation is used to select the process model to be used, that is, which MPM module to use. Beos and mpmt_os2 are the default MPM on BeOS and OS/2, respectively. Perchild is mainly designed to run different child processes as different users and groups. This is particularly useful when running multiple virtual hosts that require CGI, which is better than the SuExec mechanism in version 1.3. Both leader and threadpool are based on worker variants, are still in the experimental stage, and in some cases do not work as expected, so Apache officially does not recommend it. Therefore, we mainly describe prefork and worker, the two product-level MPM that have the greatest relationship with performance.

How prefork works

If you do not use "--with-mpm" to explicitly specify that some kind of MPM,prefork is the default MPM on the Unix platform. The pre-spawning child process adopted by it is also the mode adopted in Apache 1.3. Prefork itself does not use threads, version 2.0 uses it to maintain compatibility with version 1.3; on the other hand, prefork uses separate child processes to handle different requests, which are independent of each other, which makes it one of the most stable MPM.

The principle of prefork is that after the control process initially establishes the "StartServers" child process, in order to meet the needs of the MinSpareServers setting, create one process, wait one second, continue to create two, and then wait one second, continue to create four. This increases the number of processes created exponentially to a maximum of 32 per second until the value set by MinSpareServers is met. This is the origin of prederivation (prefork). This mode eliminates the need to generate new processes when the request arrives, thus reducing system overhead to increase performance.

How worker works

Relative to prefork,worker, it is a new MPM in version 2.0 that supports a mixed model of multi-threading and multi-process. Because threads are used to process, it is possible to handle a relatively large number of requests, and the overhead of system resources is less than that of process-based servers. However, worker also uses multiple processes, and each process generates multiple threads to achieve process server-based stability. The way MPM works will be the trend of Apache 2.0.

The principle of worker is that "StartServers" child processes are generated by the main control process. Each child process contains a fixed number of ThreadsPerChild threads, and each thread processes the request independently. Similarly, in order not to generate threads when the request arrives, MinSpareThreads and MaxSpareThreads set the minimum and maximum number of idle threads, while MaxClients sets the total number of threads in all child processes. If the total number of threads in the existing child process does not meet the load, the control process will derive a new child process.

# next I will compile and install in worker mode

#. / configure-- prefix=/usr/local/apache-- with-mpm=worker-- enable-so (let it support the DSO function so that the module can be loaded dynamically later)

# make

# make install

# cd / usr/local/apache/conf

# vi httpd.conf

StartServers 2 MaxClients 150 ServerLimit 25 MinSpareThreads 25 MaxSpareThreads 75 ThreadLimit 25 ThreadsPerChild 25 MaxRequestsPerChild 0

The total number of requests that can be processed simultaneously in Worker mode is determined by the total number of child processes multiplied by the ThreadsPerChild value, which should be greater than or equal to MaxClients. If the load is so heavy that the number of existing child processes cannot be satisfied, the control process will derive new child processes. The default maximum number of child processes is 16, and you also need to explicitly declare ServerLimit when enlarged (the maximum is 20000).

It is important to note that if ServerLimit is explicitly declared, its value multiplied by ThreadsPerChild must be greater than or equal to MaxClients, and MaxClients must be an integral multiple of ThreadsPerChild, otherwise Apache will automatically adjust to a corresponding value (which may be an unexpected value). The following is the author's worker configuration section:

StartServers 3 MaxClients 2000 ServerLimit 25 MinSpareThreads 50 MaxSpareThreads 200 ThreadLimit 200 ThreadsPerChild 100 MaxRequestsPerChild 0

# Save exit.

# / usr/local/apache/bin/apachectl start

# the core parameters related to Apache can be configured according to the actual situation to achieve maximum performance and stability.

2. Limit the number of Apache concurrent connections

We know that when the website provides software download in the way of http, if each user opens multiple threads and there is no bandwidth limit, it will soon reach the maximum number of http connections or cause network congestion, making many normal services of the site unable to run. Let's add a mod_limitipconn module to control the number of concurrent connections to http.

The directory restricted by # wget #, which means that the number of concurrent connections per IP is limited by MaxConnPerIP 2 #, the root directory of the host.

# Save exit.

# / usr/local/apache/bin/apachectl start

# Let's test it with ants or express, as shown in figure 1:

As shown in the above figure, the configuration is successful.

Third, prevent documents from being hacked.

We have just limited the number of IP concurrency, but if the other party steals the link to another page, what we just did is meaningless, because he can download it through ants or express cars. So in this case, we will refer to the mod_rewrite.so module. In this way, when he hacked the file, the mod_rewrite.so module led the page to an error page that we had made in advance, thus preventing the hotlink.

# / usr/local/apache/bin/apxs-c-I-a / opt/httpd-2.0.52/modules/mappers/mod_rewrite.c

# after compilation, mod_rewrite.so will be automatically copied to / usr/local/apache/modules and your httpd.conf file will be modified.

# vi / usr/local/apache/conf/httpd.conf

RewriteEngine onRewriteCond% {HTTP_REFERER}! ^ http://www.squall.cn/.*$ [NC] RewriteCond% {HTTP_REFERER}! ^ http://www.squall.cn$ [NC] RewriteCond% {HTTP_REFERER}! ^ http://squall.cn/.*$ [NC] RewriteCond% {HTTP_REFERER}! ^ http://squall.cn$ [NC] RewriteRule. *\. (jpg | gif | png | bmp | tar | gz | rar | zip | exe) $http://www.squall.cn/error.htm [rjjnc]

# Let's open a browser to test http://dominia.org/djao/limit/mod_limitipconn-0.22.tar.gz

# tar zxvf mod_limitipconn-0.22.tar.gz

# cd mod_limitipconn-0.22

# / usr/local/apache/bin/ apxs-c-I-a mod_limitipconn.c

# after compilation, mod_rewrite.so will be automatically copied to / usr/local/apache/modules and your httpd.conf file will be modified.

# vi / usr/local/apache/conf/httpd.conf

# add on the last line

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