Why is there so much data in the session restore anyway? If the goal is to have the URLs of the currently opened tabs, I'd expect that just the given URLs should be enough? I think I've seen some unexpected stuff there like the images base64 encoded? Maybe there's enough users that would be satisfied just with the URLs? At least for them the "rewrite" would be seldom needed.
Or, maybe to reformulate, which wild scenarios does Firefox want to support now? I can imagine that the user's experience wouldn't match the wishes. Some people that use session restore claimed they "lost everything" from time to time, and I had to fish "just the urls" from their session store files which looked strange ("full of everything"), but automatically restored to nothing.
Session store contains open tabs, windows, history for each tab, form fields, referrers (so we can re-request the page correctly), titles (so we can restore tabs without re-fetching every page), favicons, charsets, some timestamps, extension data, some kinds of site storage, scroll positions, and a few other things.
The goal of session restore is to restore your session -- your open tabs should come back, the same pages should load, scrolled to the same place, and with the right content.
I'd wish they'd also restore themselves to the proper location on the proper virtual desktop. With hundreds of windows, typically organized by task, I dread having to reorganize things every time Firefox (or the computer) restarts.
Someday the pain may motivate me to try to learn enough about Firefox's internals to do it. :)
Definitely worth filing a bug in bugzilla if they are not on the right virtual desktop... it might take years to get fixed, but they do generally get round to it.
Storing a lot of static images as JSON base64 encoded, every 15 seconds is certainly not something that users should be blamed ("some users have 300MB JSON files"), just the poor programming.
It would be interesting if somebody would actually analyze what takes the most of the mentioned 300 MB. I see a lot of base64 encoded stuff, if they are "favicons," come-on. There are so many caches in Firefox already, JSON files certainly aren't the place for these images.
700 KB of binary images in a 1.7 MB session file, which can be compressed only to the 70% of its size.
I also see a lot of things like \\u0440 which spends eight characters for one unicode character (in another file, not from me). But that file was reduced to 37% of initial size with LZ4. It seems LZ4 is still worth doing, if the content remains easily accessible with the external tools, e.g. lz4cli.
As an Fx user, I'm glad that favicons are stored though. The icons are a much easier, quicker indicator of what the tab is, when I'm scrolling through dozens of tabs to see which one to click and load.
There's no need to store favicons in the session JSON. They're stored in the browser cache. If the cache gets cleared in the meantime, they can be redownloaded.
Agreed. If my computer crashes (once in a blue moon) I would be happy for it to just open the urls again. I don't care whatsoever about it keeping the current state of every tab. If any users do care about that, it should be optional (perhaps a tickbox in the preferences window).
My FF has crashed many times on OS X and while it does restore the URLs, it has never restored the state. I know it because sometimes I am in the middle of writing a comment and it crashes. On recovery, the comment is gone.
Or, maybe to reformulate, which wild scenarios does Firefox want to support now? I can imagine that the user's experience wouldn't match the wishes. Some people that use session restore claimed they "lost everything" from time to time, and I had to fish "just the urls" from their session store files which looked strange ("full of everything"), but automatically restored to nothing.