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This article introduces the knowledge of "how to solve the script blocking problem caused by Session in PHP". In the operation of actual cases, many people will encounter such a dilemma, so 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 solution to the session blocking problem: call session_write_close () after the session operation is completed to avoid this problem

Case 1:

In the process of using session, after opening session, the same browser executes the same program, and different pages are locked. This does not happen in different browsers.

Question: is session_start causing the blockage?

So I wrote a few pages and tested it, and found that session caused the blocking, while the other two cases did not.

Looking at PHP's Bug list, it was found that this question was raised:

The copy code is as follows:

Description:

-

Calling session_start () appears to wait until other scripts have exited

That are using the same session. My guess is the 1st request locks the

Session file for exclusive use, and the second request blocks until it

Can open it.

The official response from PHP is:

The copy code is as follows:

Thank you for taking the time to write to us, but this is not a bug.This is expected, the session file is locked to avoid corruption.

Combined with the Session mechanism of PHP, the cause of blocking is found. Because the Session information of PHP is written to the file, 1 client owns 1 session file. Therefore, when session_start is called, the file is locked and locked in read-write mode (because the value of session may have to be changed in the program), so that the second call to session_start is blocked.

The simplest solution:

Check the PHP manual and find a session_write_close function that acts as Write session data and end session, that is, to write the data of session, while closing the session. Therefore, after we have finished using session, we can call this function to close the session file and unlock it. In general, session is used to record user identity information so that PHP can authenticate, so you can put the read and write of session at the beginning of the page, and call the session_write_close function immediately after execution.

Case 2:

Last time, I said that to change opencart is to add a function to opencart to grab products on Taobao, but after finishing it, I found a problem, that is, when the script was crawling, because the process was relatively slow, the execution of all other scripts was blocked until other scripts were crawled. After studying it for a long time, there was no result. I asked the question of session on Zhihu, which needs to be solved by calling session_write_close (). Then what is the use of this session_write_close ()? it is written in the manual:

The copy code is as follows:

End the current session and save the session data.

Session data is usually saved at the end of script execution without calling session_write_close (), but to protect that session can only be written by one script at any time, session data is locked. When using frame pages and session at the same time, you will find that the pages in the frame will be loaded one by one because of this lock. You can speed up the load time by ending session as soon as all session data changes are saved.

This is a good explanation for why my crawl script blocks other pages. So, if you have an ajax request that takes a long time to execute and uses session, you need to call session_write_close () on the server side, otherwise your other pages will be suspended until the request ends!

This is the end of "how to solve the problem of script blocking caused by Session in PHP". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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