How to handle time-consuming tasks in php

When the server access pressure is relatively high, we can use load balancing to distribute the load to multiple servers. But there are some more time-consuming requests. For example:

1. You need to connect to the mail server and send a very long HTML email. (Recommended learning: PHP Video Tutorial)

2. The images uploaded by users need to be cropped and multiple thumbnails generated.

3. Files uploaded by users need to be distributed to multiple servers.

We often encounter in our daily applications that the user needs to wait for a period of time before the request can be completed. When the user uploads a photo, after the photo is uploaded successfully, it is then cropped and finally a thumbnail is generated. In such a During the process, the user can only wait, so the user experience is quite bad.

Maybe after the user uses it for the first time, it will be difficult for him to use this image upload function next time.

So is there a way to run these processes slowly in the background?

The answer is yes. Through distributed processing, these time-consuming tasks can be placed in the background, or even distributed to multiple servers for processing. Asynchronous processing comes in handy for this problem.

There are many open source software that can achieve asynchronous communication, such as ActiveMQ, Hadoop, Gearman and MecacheMQ, etc. They cleverly transfer calculations to other servers, and all of this is hidden in the API. At the same time, These mechanisms are cross-language. You can use PHP to assign a task, and then use the background C/C program to process it. This is not a problem.

The following uses php and Gearman to demonstrate the asynchronous processing process.

1. Installation of Gearman

tar zxvf gearmand-0.11.tar.gz
cd  gearmand-0.11
./configure --prefix=/usr/local/gearman
make
make install

2. Installation of Gearman PHP extension.

　tar zxf gearman-0.6.0.tgz
cd gearman-0.6.0
　 phpize
　 ./configure
　 make

Copy gearman.so in the module directory to the module directory of php. The directory of my machine is /usr/lib/php5/20060613 lfs/.

cp module/gearman.so /usr/lib/php5/20060613 lfs/.

Then add

extension = “gearman.so”

to php.ini and finally restart the apache server.

3. Start the Gearman service

cd /usr/local/gearman/sbin
./gearman -d -u root

The default port of Job is 4730, which can be started by

[root@serv_1 sbin]# netstat -nl | grep 4730
tcp        0      0 :::4730                     :::*                        LISTEN

.

Through bin/ With gearman, we can experience the functions of Gearman.

Start Worker:

./gearman -w -f wc -- wc -l &
[1] 2547

Run Client:

./gearman -f wc < /etc/passwd
38

In the above example, a function wc is defined in the Worker. Its main function is to count the number of lines of text. The client passes the contents of the /etc/passwd file to the Worker for processing. Finally, it is concluded that passwd has 38 lines of text.

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