Grails startup is slow

Question

Help! I'm porting a large ruby app to Grails - but the Grails startup of my application takes more than 2 minutes.

I've already set dbCreate to "read" I've ensured my high end dual processor desktop windows box gives Grails needed RAM (1 Gig). I have no plugins installed. I have 170 domain classes that used to be ruby classes.

When it starts up it prints out the line "Running Grails App.." and then hangs for a long time before it then prints out the "Server running" line.

I just did something where I migrated all my ids to bigints. That seems to have worsened the problem. Now it takes about 10 minutes to startup.

I am new to grails would you please give me a few more details on what and where to log the events at startup? As to profiling the vm, its been a few years since I did a lot of Java. What do you recommend as the best profiling tool to use now?

What else can I do to speed up Grails startup?

Answer 1

Unfortunately, I am not sure too much can be done beyond what you already did. As you know, there is a lot going on when it starts up, with all the plugin resolution / loading, adding dynamic methods to your domain objects, and overall dynamic nature of Groovy.

I am not sure which version you are using, but I've asked for ability to turn off dependency checking when you start up in 1.2, since that adds a bunch of time to startup time as well.

I realize above isn't too helpful, so perhaps this will be: I split up my application into several plugins. One for domain objects, one for graphing capability, one for excel import, another for some UI constructs I needed. I didn't do it just because of slow startup times, but the advantage is that I can test parts of the system separately from each other before integrating everything together.

I am about to add a piece of new functionality that involves at least 10 new domain objects, and I am first developing them in a separate plugin by having stubs for the few objects they have to interact with from the core app. That allows me to both reduce startup times, and also have my code better isolated.

So if it's an option for you, try to separate out things so you can work on them separately, which will alleviate your issue somewhat. There may also be other benefits in terms of having your team work on smaller components separately, better modularization, etc.

Hope this is helpful.

Answer 2

You might want to see if there are other knobs you can turn other than Grails in order to fix this.

Have you tried approaching this as a performance issue? You can a look at the box performance and try to find out what the bottleneck is. Is it CPU? Is it a disk read issue? Can you attach a profiler to the VM and find out what's using up most of your startup time?

Answer 3

170 domain classes is fairly large, but 2 minutes still seems really long to me. Do you have a ton of plugins installed? Potentially too verbose debug settings?

I'd be curious how long it took if you created a fresh grails app, copied in all of your domain objects (and the subset of plugins that the domain objects might need to actually operate) and see how long that takes to start.

Jean's suggestion about separating things out if possible is a good one. I've done something similar on previous projects where we have a domain plugin, and our other apps all rely on that domain plugin.

You could also use the grails events to log some timing information on start up to see where your bottlenecks are. Timing the "PluginInstalled" event should be good as I think that the hibernate plugin would be caught by this in addition to the other plugins.