Firefox "Studies" system brief technical investigation: Normandy, recipes, and what's going on behind the scenes (no drama) 

It's kind of neat to dig into 's "Studies" system, i.e. .

I'm highly interested in , flipping on the new Rust bookmark sync engine in stable - I've had out-of-order syncs with the old engine, which the new one should fix.

So, by viewing a graphical browser of Shield studies here:

I narrowed it down (check the "Surveys" box so all are enabled). Or, better yet, with Firefox's JSON viewer, you can directly browse the 1.26 MB JSON blob at

With this, I found the experiment I wanted by filtering on services.sync.bookmarks.buffer.enabled. I can tell that 25% of folks currently have it thanks to the filter_expression:

"( in [\"release\"]) && ((normandy.version>=\"70\"&&normandy.version<\"71\")) && ([\"new-sync-70\",normandy.userId]|bucketSample(0,250,1000))"

I.e. bucketSample(0, 250, 1000), creating 1000 buckets with 250 of them selected.

Which is documented here, along with the rest of Normandy on one of 's websites:

…I could just flip the pref manually in about:config, but I feel like I should wait for the rollout for some reason.

Sign in to participate in the conversation
The Vulpine Club

The Vulpine Club is a friendly and welcoming community of foxes and their associates, friends, and fans! =^^=