#1458 new
Michael Gottschalk

Slowness in Development Mode

Reported by Michael Gottschalk | March 9th, 2012 @ 01:21 PM

In Development mode, many small, subsequent requests are slow because of the change detection.
Change detection is done on every request and in a synchronized method.

I attached a patch that has the effect that change detection is only performed every 2 seconds at most, which significantly
increases the speed of page loads with many requests.

Framework version: 1.2.4, with Scala Module (0.9.1)
Platform you're using: MacOS X Lion, Java 1.6.0_29

Reproduction steps:

Details:

Discussion on the mailing list:
https://groups.google.com/forum/?hl=de&fromgroups#!topic/play-f...

Text from the mailing list message:

I have a Play app that creates quite a few requests for one page view.
In Development mode, this is very slow, because the requests are all handled sequentially.
I increased the property "play.pool" in application.conf, but it did not have any real impact.
The requests still seemed to be handled sequentially.

I looked through the play source code for finding the reason for this behaviour. I saw that the pool size was indeed increased, so that did not seem to be the problem.
Instead, the real problem was the change detection in development mode. This is performed for every request and it is done in a synchronized method.
I attached a diff for a change I made: The change detection is now only performed if the last change detection was at least 2 seconds before.

This change significantly increases the speed in Development mode if there are many small requests at once, because they can now be performed in parallel. And I think that there will hardly be any changes that are more frequent than every 2 every seconds.

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<h2>Play framework</h2>

Play makes it easier to build Web applications with Java. It is a clean alternative to bloated Enterprise Java stacks. It focuses on developer productivity and targets RESTful architectures. Learn more on the <a href="http://www.playframework.org">http://www.playframework.org</a> website.<br><br>

<h2>Source code is hosted on github</h2>Check out our repository at <a href="http://github.com/playframework/play">http://github.com/playframework/play</a><br><br>

<h2>Contributing, creating a patch</h2> Please read the <a href="http://play.lighthouseapp.com/projects/57987/contributor-guide">contributor guide</a><br><br>

<h2>Reporting Security Vulnerabilities</h2> Since all bug reports are public, please report any security vulnerability directly to <em>guillaume dot bort at gmail dot com</em>.<br><br>

<h2>Creating a bug report</h2> Bug reports are incredibly helpful, so take time to report bugs and request features in our ticket tracker. We’re always grateful for patches to Play’s code. Indeed, bug reports with attached patches will get fixed far quickly than those without any.<br><br>

Please include as much relevant information as possible including the exact framework version you're using and a code snippet that reproduces the problem.<br><br>

Don't have too much expectations. Unless the bug is really a serious "everything is broken" thing, you're creating a ticket to start a discussion. Having a patch (or a branch on Github we can pull from) is better, but then again we'll only pull high quality branches that make sense to be in the core of Play.

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