Why aren't my JQuery .ajax requests being made in parallel?

Question

I am trying to make two ajax requests in parallel using jQuery like this:

    var sources = ["source1", "source2"];

    $(sources).each(function() {
      var source = this;
      $.ajax({
        async: true,
        type: "POST",
        data: {post: "data", in: "here"},
        url: "/my/url/" + source,
        success: function(data) {
          process_result(data);
        }
      });
    });

I got the basic structure from this question, but my requests still aren't being made in parallel. "source1" takes a while to complete, and I can see on the server that the second request isn't made until the first is completed.

As far as I can tell, I don't have any other active requests, so I don't think it's a problem with the maximum number of parallel requests for the browser. Am I missing something else here?

I just re-tried my answer from that linked question and added a `sleep(4);` in the PHP page - still worked as expected. All 4 requests fired at once and all took ~4 seconds to complete. — Peter Bailey, Mar 29 '10 at 18:45
Backend was Catalyst running in my development sandbox without the --fork option. The Net panel in Firebug didn't display the second request until the first had completed. — Ryan Olson, Mar 30 '10 at 12:55

Matt · Accepted Answer · 2012-05-22T07:15:23.620

13

jQuery does not queue AJAX requests. If you're sure you're not making any other requests your end, how about the server? Maybe it only has one worker?

EDIT: And just to make sure, I tested it with a script that launches 2 AJAX POST requests to a PHP script which sleeps for 5 seconds. They were not queued.

edited May 22 '12 at 07:15

answered Mar 29 '10 at 18:43

Matt

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Seems like a server related issue. – BYK Mar 29 '10 at 18:50
1

Yes, was running my web server in my development sandbox without the --fork option, so it was only handling one request at a time. – Ryan Olson Mar 30 '10 at 12:53

score 8 · Answer 2 · answered Mar 29 '10 at 20:22

8

are you using php? are you using session_start()? sessions cannot be opened in parallel by multiple requests, to they will wait one after another to finish what they're doing.

answered Mar 29 '10 at 20:22

Quamis

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Man, I love you !!!!!! Totally forgot this, lost 3 hours until your post ;-( A big thanks from south of france ^^ – Thomas Decaux Jan 17 '13 at 20:53

score 0 · Answer 3 · answered Mar 29 '10 at 18:48

What if you used $.post instead of $.ajax. This works for me.

var sources = ["source1", "source2"];

$(sources).each(function() {
  var source = this;
  $.post("/my/url/" + source, {post:"data", in:"here"}, function(data) {
      process_result(data);
  });
)};

Why aren't my JQuery .ajax requests being made in parallel?

3 Answers3

Linked