Java: May 2010 Archives

I knew I could get Java working in Firefox on my Tiny Core 2.11 Linux installation. I just had to think about it for a while.

I first tried the OpenJDK packages in Tiny Core, but those didn't work. Now that I know what I'm doing ... sort of ... I could probably get them to work, but I went about things another way.

Before I start, let me just stay that I didn't do this the entirely "kosher" way, but it works and for now (and for my idea of what Tiny Core is), I'm OK with it.

First I got the self-extracting Java runtime from Java.com.

After a few aborted attempts, I decided to do this in the /home directory, which in Tiny Core is /home/tc

I had the self-extracting .bin file jre-6u20-linux-i586.bin in the Desktop portion of the /home directory. I made a directory for it:

tc@box:~$ mkdir java

Then I moved the .bin into it — I wanted everything where I could keep an eye on it:

tc@box:~$ cd Desktop

tc@box:~$ mv jre-6u20-linux-i586.bin /home/tc/java

I went into my new directory and, per instructions from java.com, made the file executable:

tc@box:~$ cd /home/tc/java

tc@box:~$ chmod a+x jre-6u20-linux-i586.bin

Then, also per java.com instruction, I extracted and installed the archive:

tc@box:~$ ./jre-6u20-linux-i586.bin

After scrolling through the boilerplate EULA, I agreed to the terms and had the Java runtime installed in the directory I created.

(I know that it's better to have this somewhere under usr/bin, and I might very well move it later, but for now this works, so I'm keeping it.)

The next step was making the symbolic link to the plugin. Most instructions say to make this link in /home/tc/.mozilla/plugins. THIS DID NOT WORK in Firefox 3.0.4 aka Minefield.

Instead, the place to make the symbolic link is /usr/local/firefox/plugins

So opened a terminal, switched to root and did that:

tc@box:~$ sudo su

tc@box~# cd /usr/local/firefox/plugins

tc@box~# ln -s /home/tc/java/jre1.6.0_20/plugin/i386/ns7/libjavaplugin_oji.so libjavaplugin_oji.so

That leaves the symbolic link here:

/usr/local/firefox/plugins/libjavaplugin_oji.so

which leads to:

/home/tc/java/jre1.6.0_20/plugin/i386/ns7/libjavaplugin_oji.so

Remember, it was my choice to extract and install the Java runtime in the /home directory. There are probably better places for it, but until I know Tiny Core a whole lot better, I'll keep it where I can see it ...

I started Firefox 3.0.4 (aka Minefield) looked in Tools - Add-ons - Plugins, and the Java plugin was right where it was supposed to be.

Just to be sure Java will run in the browser, go to Edit - Preferences - Content and be sure the "Enable Java" box is checked.

Another way to check for Java is to go to about:plugins in the URL window of the browser. You should see a long list of Java-specific output.

I did confirm that Java works in Minefield/Firefox, and now I can use Tiny Core for those few yet critical tasks that require the Java runtime, making TC that much more valuable to me.

Potential problem: One thing I'm noticing is that the java_vm process is still knocking around in my system, even though I'm not using the Java runtime at this particular moment.

It wasn't using any CPU but was eating about 400 MB of RAM. Nice little thing, that Java.

I killed java_vm in a terminal, and it took Firefox/Minefield with it. Nice.

So I have Java, but I'll be keeping an eye on it, wondering if it will behave (and checking my other systems for errant java processes that run on too long).

As a way of explaining what this is all about, Cameron Simpson wrote the following way back in 2005:

The JVM gets started once and hangs around because a JVM has a noticable startup cost. If you want web pages with Java content to be "snappy" in loading (bandwidth aside) it helps if the JVM is already present and initialised, and so it doesn't go away when idle.

Provided it's consuming no CPU then it's no added burden on your system; memory contention will page it out to your swap space if necessary.

Do you have a technical reason for wanting it gone or does it just seem "untidy" to your eye?

I hope that's true. In my case, the /swap on my drive is encrypted and not available to be used by Tiny Core, so I'll be keeping an eye on java_vm when I run Java in TC.