Monday, December 31, 2012

Adventures in Pi Land Part Two

In the first part of this blog we looked at the initial setup of the Raspberry Pi. In this one we'll look first at building and running Fuse Fabric, followed by vert.x. So first Fabric and before I go on it's worth mentioning that this is still not complete and I need to check with the team in the new year to figure get more details on the problems, which could very well be due to my setup on the Pi.

Initially we had 256 Meg of swap and with maven2 installed the Fabric build docs tell us to use the m2 profile option (and the right MAVEN_OPTS). Unfortunately the initial build attempt failed with maven2, so I installed maven 3.0.4 which gets us a little further:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.12:test (default-test) on project archetype-builder: Error while executing forked tests.; nested exception is Cannot run program "/bin/sh" (in directory "/home/pi/fusesource/fuse/tooling/archetype-builder"): error=12, Cannot allocate memory -> [Help 1]

So we increase swap to 1024 Meg by again editing the /etc/dphys-swapfile as mentioned before. This helped, but even with these options, the Pi crashed after about 6 hours of building. (Yes, the Pi crashed!) And as you can see from the screen shot, prior to this Java was taking up a lot of the processor time.

And if not Java, then writing to swap:

After playing with more configuration parameters (with failures 6+ hours later) and ordering a faster SD card (which has not turned up at the time of writing), I decided to try the the latest official binary of Fabric from the download site (fuse-fabric-7.0.1.fuse-084) - no point struggling to get it to build if it won't run anyway. Working through the Getting Started tutorial did not produce the expected output, which needs investigation once I get back to work and can talk with the team. For instance, when trying to use camel ...

And over 7 minutes later the same command gave:

And running top showed the processes were fairly idle:

I spent a few more hours trying other options, but nothing really seemed to make a difference or indicate whether the issues were with the Pi or elsewhere. But I still consider this a success, since I learnt a few things more about the capabilities and limitations of the Pi that I hadn't before, as well as about Fabric (which was the original project I had set myself). And I will return to this and see it through the completion soon.

So onwards to vert.x. Initially I decided not to build the latest source, but to just see if the official binary would run. Now vert.x requires JDK 7, so we need to download and that from Oracle. Next, downloading and installing and following the installation guide brings us to:

Success! It took over a minute for the server.js example to initialise (since I'm connecting remotely to the Pi, I changed localhost to the actual IP address). But HelloWorld eventually worked.

We're on a roll here! Next we moved on to the JavaScript Web Application Tutorial - I want to test as much of vert.x as possible and implicitly the Raspberry Pi's boundaries. This tutorial needs MongoDB. Unfortunately you can't just install the Linux distribution version as it's not suitable for the Pi. I looked around to see if there was a build I could get elsewhere and found one, but unfortunately that needs the hardware floating point version of Wheezy, which we can't use if we are using Java 6 or 7.

Someone said that you can build an older version of MongoDB from source which I tried. To do this I made sure we were still working with 1024 Meg of swap. But unfortunately after about 10 hours, the build failed:

Fortunately a little digging around found a couple of other options and I went with the first, i.e., Still with 1024 Meg of swap, after 12 hours of building and similarly for installation, I ended up with a running version of MongoDB on the Raspberry Pi!

I was then able to progress through the example, but still had a few failures due to incorrect module versions mentioned in the walkthrough. Thanks to Tim for giving the right numbers and he's going to update the pages asap. There are still a few niggles with the example failing during authentication, but I can live with them for now and will get to the bottom of them eventually.

But what about building vert.x from scratch on the Pi? Well that was a lot easier than I had thought given everything else that's happened so far. Building vert.x head from source and getting Jython 2.5.2,  we initially get an error:

But if you use the nightly build of gradle:

Which eventually results in ...

Success again!

So what does all of this mean? Well apart from the obvious areas where I still need to see success, I think it's been a great exercise in learning more about the Pi. I've also learnt a lot more about the various projects I wanted to play with this festive season. I'm happy, even if it did take quite a few more days to do than I expected originally!


Unknown said...

Hi Mark, thanks for sharing your experiences. I also got vert.x running on a pi, but when I wanted to do something more serious, running the event bus example app (examples/java/eventbusbridge), the CPU went to 100% and stayed there, never responding to web requests or exchanging messages on the event bus. I use openjdk 7 on a wheezy distro, so hardware floating point should be supported. Still I am curious to know if your setup has more success. If all fails, I want to consider making the pi connect to the event bus through a dedicated host, much like javascript clients can participate on the event bus, but then using java code. Naturally this is less elegant than transparently hooking up to the cluster. Hope to hear from you. Jeroen

Mark Little said...

Hi Jeroen. I'll take a look at that example myself this week. I'm currently using the soft float version of Wheezy, but would have thought that would simply make my system slower. I'll let you know here how it goes.

Mark Little said...

Jeroen, check out