While I'm restoring a large session, there's an intermediate state during the restoration where we're writing to sessionstore.js, but only a small part of the information that should be in it is in it. If Firefox crashes during this time, for example, due to an intermittent crash on one of the pages in the session being restored, I'll end up losing most of the information about my session. Steps to reproduce: 1. restore a large session 2. monitor the size of the sessionstore.js file while the session is being restored Actual results: For a while, sessionstore.js isn't touched at all. Then, it gets much smaller and then grows back up to its original size. Expected results: sessionstore.js modified at the very beginning to note that the browser was running (and that a further restore should give the restore-from-crash dialog), but not otherwise shrunk during the restoration process. (If windows/tabs are opened/closed before the restore is complete, that information should be recorded properly as well.) Seen in: Linux debug build, 2007-12-19 (and for a long time before that)

Does this happen for large single-window sessions or only for multi-window sessions? If the latter is the case then this is probably a dupe of bug 395488. Otherwise it would help to get two differently-sized snapshots of sessionstore.js from during the same startup process. BTW: Does sessionstore.js get modified during the first 10 seconds? It shouldn't...

This does not block the final release of Firefox 3.

FIXED in bug 395488.