Profiling Sync on Fennec

Summary

Fennec sync continues to cause performance issues on first time syncing with very large amounts of data. More specifically, there are still millions of javascript objects that sit on the IO thread that Garbage collection does not clean up properly.

How you can help, Provide sync logging through a custom extension, and submit your data to the Mozilla Services team. Follow the instructions below

Steps to execute

1. Pick a Sync account with lots of data in it. The more history, bookmarks, etc., the better.
2. Install Fennec on the Android phone. If it's already installed, clear all data in Applications > Manage Applications > Fennec.
3. Go to http://bit.ly/syncaddon to install the sync extension
4. After the add-on has been installed, restart Fennec. (Verify that the Sync add-on is installed in the add-ons manager)
5. Connect to your Sync account using the easy setup (aka Jpake authentication method).
6. Press "Sync Now" immediately after connecting
7. At the end of the Sync, mount the internal disk via USB and get the "sync-log-NNNN.txt" files. These files should live in your /mnt/sdcard/downloads directory. There may be more than one file. Just select the largest file size (eg. 800k, 1.2Mb)
8. Repeat all steps for Three Runs per phone. Then do the following:
   • Rename log files to phone and data in the name. (eg. NexusS_20100309_1.txt, NexusS_20100309_2.txt, etc..)
   • Email them to philikon@mozilla.com
   • Then, make sure that you always clear Fennec's data (step 2)
   • Reboot Fennec (step 3) to get absolutely repeatable data.
   • when uploading your data, indicate what type of phone and build you are using.

Resources

• Philikon's Sync Instrumentation Research
• Blog on profiling Javascript Objects