CODEWITHSUNDEEP
javascriptphpajaxdojo
Varin
Varin

Reputation: 2443

Dojo: all xhr / ajax calls seem to be synchronous and block other calls

I am working on a CRM we inherited. Long story short - there is a button that calls a php script which should run in background and we don't need to wait for response. 

request(idata+'transferInTimeExec.php',{
    sync: false,
    preventCache:true,
    method:'GET'
});

Now, the transferInTimeExec.php takes an hour to run, it's a very complex script that deals with weekly timesheets for a recruitment company, processes them, does a lot of DB operations etc.

Using Chrome. Every time I press the button to run it, it blocks all the xhr calls until it finishes. CRM is "ajax heavy" and while the script is running, the user can't do anything, if they navigate to another subpage, no xhr requests will resolve until that process we started has finished. Even when I open a new browser tab and try to do something, it won't do it. If I open the CRM in another browser (Firefox) while the script is running, I can use the CRM.

In Network tab - the first one is pending, and as you can see all the subsequential calls to a different Ajax call wait (all have sync:false)

enter image description here

I even replaced the whole logic with PHP function sleep(30) to make it just do nothing for 30 seconds before returning anything - same issue.

I tried XHR in plain javascript, inside onClick on the button HTML markup, rather than Dojo methods - same issue.

I've done a brutal Search/Replace on the whole project, replacing sync:true to sync:false - nothing changed.

I have run out of ideas, maybe anyone here can help to figure this out? Is there a global switch for sync/async? What else could it be if not ajax issue?

Upvotes: 5

Views: 589

Answers (1)

ascsoftw
ascsoftw

Reputation: 3476

Your script transferInTimeExec.php is probably using session. When thats the case, other AJAX Call would not initiate and instead wait for this AJAX Call to Finish so as to not overwrite the session data. Setting AJAX call to asynchronous does not change the behavior.

If this script takes 1 hour to run it is a bad idea to call it as an AJAX from UI. You should setup a Cron, hourly or daily, and perform all the operations in the backend. Of course, you will need to make some adjustment to the script if it is using session.

EDIT

You could use session_write_close(); at the top of your script. This tells the PHP that this script would not write anything to the Session so other AJAX Calls are free to use the Session. However be careful to not write anything to Session after this as this will result in an error.

Upvotes: 3

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