Windows PHP通过popen重复脚本

Question

I'm trying to create a browser-started self-calling/repeating PHP script on Windows with PHP (currently 5.3.24 but soon will be latest). It will act as a daemon to monitor changes in a database (every few seconds, so cron/schedule is out) and then call other PHP scripts to perform work when changes are found. For the purposes of this question please ignore the fact that I'd be better off doing this in C# or some other language :)

To keep things simple I started out by trying to use popen to run a second PHP script in the background...

// BatchMonitor.php
SaveToMonitorTable(1);   // save 1st test entry to see if the script reached this point

$Command = '"" "C:\Program Files (x86)\PHP\v5.3\php.exe" C:\inetpub\wwwroot\Test.php --Instance=' . $Data->Instance;

pclose(popen("start /B $Command", "r"));
SaveToMonitorTable(2);   // save 2nd test entry to see if the script reached this point
exit();


// Test.php
SaveToTestTable(1);
Sleep(10);
SaveToTestTable(2);
exit();

If I run BatchMonitor.php in the browser it works fine. As expected it will save 1 to the monitor table, call Test.php which saves 1 to the test table, the original BatchMonitor.php will continue without waiting for a response and save 2 to the monitor table before exiting, then 10 seconds later the test page saves 2 to the test table before exiting. The second script starts fine, the first script does not wait for a reply and all parameters are correctly passed between scripts. With everything working as intended I then changed the system to work as a repeating loop by calling itself (with delay) instead of another script...

// BatchMonitor.php
SaveToMonitorTable(1);   // save 1st test entry to see if the script reached this point

$Command = '"" "C:\Program Files (x86)\PHP\v5.3\php.exe" C:\inetpub\wwwroot\BatchMonitor.php --Instance=' . $Data->Instance;

pclose(popen("start /B $Command", "r"));
SaveToMonitorTable(2);   // save 2nd test entry to see if the script reached this point
exit();

If I run BatchMonitor.php in the browser it runs once and that is it. It will save 1 to the database, wait 10 seconds and then save 2 to the database before exiting. The page returns successfully with no script or PHP errors but it doesn't repeat as it should.

Both BatchMonitor.php and Test.php use line-for-line identical functions to get the parameters and both files run correctly and identical on the first iteration. If I use exec instead of popen then the page loops correctly with all logic working as expected (with the one obvious flaw of creating a never-ending chain of scripts awaiting for response values that will never come).

Am I missing something obvious? Does popen have some sort of secret rule that prevents a page/process from opening duplicates of itself? Are there any alternatives to using popen or exec? I read about WScript.Shell but it might be a while before I can schedule that to get enabled so for now it's not an option and I'm hoping there is something more standard that I can use.

Answer 1

I dont feel like this should cbe your actual answer, But why do you disbandon scheduled tasks/cronjobs because you want something done every X seconds? Having the script minute.php calling 5seconds.php with ofcouse 5 second intervals in between would create a repeated taak evert 5 seconds right? Strangely enough you are kinda using the same sort of mechanism from your browser already. My only concern would be to take the processed time in account and create a safe script which ensures no more than 1 '5seconds.php' can run at any given time.