Run Custom Firefox Plugins In Their Own Process

Martin Brinkmann
Jun 24, 2010
Updated • Feb 23, 2015

Firefox 3.6.4 has just been released by Mozilla after a longer than usual wait time. The new version of the web browser comes with out-of-process plugins enabled.

This feature runs plugins in their own process to improve the stability and security of the browser.

By default, only Silverlight, Flash and Quicktime are making use of this feature. Every other plugin is still running in the main Firefox process which is probably something that you may not want if you consider the benefits of the out-of-process solution.

Mozilla has however added an option to include other plugins to the out-of-process plugins list so that they are run in their own process as well.

Custom out-of-process plugins

The first step of the process is to get the filename of the plugin, this can be done via about:plugins in the Firefox address bar.

firefox installed plugins

The plugin name of the Java plugin in the screenshot above is npjp2.dll. Just look at the File reference to find the names of other plugins that are installed in the web browser.

Write down the names or open a new tab in Firefox and enter about:config into the address bar. This opens the Firefox configuration editor.

First time users need to get passed a warning message first before they can make changes.

A new Boolean preference needs to be created for every plugin that you want to be run in its own process. This is done by right-clicking in the configuration window and selecting New > Boolean from the list.

This opens a form popup where the new parameter needs to be entered. The syntax is always the same; dom.ipc.plugins.enabled.Pluginname.

For the Java file found on the screenshot above it is dom.ipc.plugins.enabled.npjp2.dll.

out of process plugins

A second option is displayed right after the creation. Setting the value of the new parameter to true enables out-of-process for the Java plugin.

boolean value

Firefox needs to be restarted before the changes take effect. Setting the value to false disables the feature again which can be helpful if a configured plugin is not running stable in its own process. (via Mozilla Links)

Article Name
Run Custom Firefox Plugins In Their Own Process
The guide provides you with information on how to run plugins installed in the Firefox browser in their own process for improved security and stability.

Tutorials & Tips

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  1. Looker Labs said on July 29, 2011 at 4:43 pm

    All fine and good.

    Anyone know how to use this thing?

    It seems…phhht

    to provide a lot of necessary tunnels

    to run 16bit apps.

  2. Taomyn said on June 25, 2010 at 9:25 am

    Is it possible that simply enabling dom.ipc.plugins.enabled from false to true will enable this for _any_ plugin that’s installed?

    1. Martin said on June 25, 2010 at 10:24 am

      Taomyn, here is my understanding of this. dom.ipc.plugins.enabled is a global setting for all plugins. This setting is overruled by specific plugin entries. If you set dom.ipc.plugins.enabled to true you can still disable individual plugins from making use of the out-of-process feature by setting them to false.

  3. bf said on June 25, 2010 at 7:10 am

    Anyhow. I used these instructions and put Shockwave, Acrobat and Java out of process.

  4. Shazam said on June 24, 2010 at 10:01 pm

    Memory Fox is still being worked on. Here’s a link

  5. Inolvidable said on June 24, 2010 at 12:55 pm

    I recommend you use Memory Fox extension. Works flawless

    1. bf said on June 24, 2010 at 5:08 pm

      Regrettably that extension was has not been updated for quite a while.

  6. Raphael Tsavkko said on June 24, 2010 at 11:28 am

    So far the new Fx sucks… I’ve installed three times and is still crashing every 5 minutes… I can’t even think about using my Brief extension… So, I’ll roll back for the previous version!

    1. Martin said on June 24, 2010 at 12:05 pm

      You might want to disable the out-of-process plugin feature to see if it fixes the issue. You can do that by setting dom.ipc.plugins.enabled to false. You might also need to set the individual plugins to false, not sure about that though.

  7. BalaC said on June 24, 2010 at 11:13 am

    Good Tip

  8. Paulus said on June 24, 2010 at 10:35 am

    Jojo you answer is to use Cleanmem the program will install and set it to run every 30 min via the windows task scheduler. And than it will run and clean the memory out of all processes.
    Next to that you want to use Memory Fox because this program flushes Firefox’s Memory Constantly. normal white 20 tabs or more i have 15 Mb memory use.

  9. Jojo said on June 24, 2010 at 10:12 am

    What I want to see is EXTENSIONS running in their own thread or process so I can see which one(s) is/are using up memory.

    I have to shut down FF at least twice daily because total memory usage gets over 1GB and then FF slows down dramatically.

    1. Martin said on June 24, 2010 at 10:16 am

      Statistic on the memory usage would indeed be very interesting. The only time-consuming option right now is to enable and disable extensions manually to identify the culprits.

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