PHP使用睡眠循环时不更新数据库直到循环结束

Question

I have a while loop with a sleep function that I wan´t to run -> update database -> sleep -> run again for a number of 10 times. With the below script the script loops 10 times, but it only updates the database when all 10 loops have finished.

I added an echo at the end just to verify, and the echo does not appear on the page until the and when every loop is echoed out at once.

I have also tried placing ob_flush() and flush() after the echo with no luck.

Script

$loops = 10;
while ($loops > 0)
{
  while($row = mysql_fetch_array($result))
  {
    // Get current User status
    $username = $row['username'];
    $user_status = $row['user_status'];
    $user_updated = date('Y-m-d H:i:s');

    // Update database
    $update_sql = "UPDATE  `database`.`user` SET  `user_status` =  '$user_status',
                                                  `user_updated` =  '$agent_updated'
                                            WHERE  
                                                  `user`.`username` =  '$username'";
    $update=mysql_query($update_sql);
    echo "Loop #".$loops."<br>";
  }
flush();
$loops--;
Sleep(5);
}

I've also tried the same with a FOR loop .
Any suggestions would be appreciated. I've gone through the search and haven´t found users with similar issues but I couldn't find the answer.

Answer 1

You can get those echoes to show one by one, but on a controlled environment (according to php documentation, flush may still buffer the output on several Win32 systems), you can read further in the php flush manual page .

To be more specific, make sure APaches mod_gzip is disabled, also, some php.ini settings like output_buffering and zlib.output_compression should be set to false.

output_buffering = false
zlib.output_compression = false

Even with all of this, you may also need to send a "big" amount of data (like 2048 chars) in order to make some browser to actually display new data.

echo "One"
echo str_repeat(" ", 2048);
Sleep(3)
echo "Two"
echo str_repeat(" ", 2048);
// Ans so on

In the comments of the aforementioned manual page, you can see more examples.

Answer 2

根据提供的代码，似乎所有更新都在第一个循环中完成，然后mysql_fetch_array（$ result）仅返回falses并且内部循环不会在其他主循环中再次进行，除非您再次填充$ result（之间）而循环标题）。

Answer 3

As pointed out by NB that PHP only returns results all at once after the script runs, I have ended with the following solution:

A bash.sh script that runs the PHP page every 5 seconds:

#!/bin/bash

set -e
count=1
while [ $count -le 12 ] :
do
  # run this scripts for one minute (12 times every 5 seconds = 60 seconds)
  /usr/bin/php -q thescript.php
  (($count++))
sleep 5
done

Then a cronjob that runs the page every minute. The above works and solves my issue.