Firefox slowdown during big IO ops

[Christopher Browne]

On Thu, Apr 29, 2010 at 2:29 PM, D. Hugh Redelmeier <hugh-pmF8o41NoarQT0dZR+AlfA at public.gmane.org> wrote:
> My theory of FireFox is that it is a monster program with really bad
> performance pathologies.  It eats unbelieveable amounts of memory and
> CPU when used the way I do: long sessions with lots of windows and
> tabs.  The obvious solutions are: switch browsers or fix FireFox.

One recent change to it which has had highly visible performance
effects was the embedding into it of SQLite.

On the instance of Firefox I have running, it has the following series
of databases:
<2g2t7pva.default>  ls -l *lite

                        <chris at dba2:>
-rw-r--r-- 1 chris chris     7168 Dec  7 13:38 content-prefs.sqlite
-rw-r--r-- 1 chris chris   454656 Apr 29 14:38 cookies.sqlite
-rw-r--r-- 1 chris chris    19456 Apr 16 14:15 downloads.sqlite
-rw-r--r-- 1 chris chris   110592 Apr 29 12:33 formhistory.sqlite
-rw-r--r-- 1 chris chris     2048 Mar 23 16:00 permissions.sqlite
-rw-r--r-- 1 chris chris 22573056 Apr 29 14:35 places.sqlite
-rw-r--r-- 1 chris chris     2048 Apr 27 15:03 search.sqlite
-rw-r--r-- 1 chris chris    44032 Apr  1 18:01 signons.sqlite
-rw-r--r-- 1 chris chris    71680 Jun  3  2009 stylish.sqlite
-rw-r--r-- 1 chris chris 32751616 Apr 29 14:09 urlclassifier3.sqlite
-rw-r--r-- 1 chris chris     6144 Jan  5 11:20 webappsstore.sqlite
-rw-r--r-- 1 chris chris  2763776 Apr 28 21:25 ybookmarks.sqlite

I tend to like this change, but it certainly comes at non-zero cost.

a) The "places" database stores bookmarks, URLs you've visited, and
data to fill into forms.  Some of it seems excessive.
b) Bookmarks also found in ybookmarks.  Probably due to some extension.
c) You're paying a lot for the "URL classifier."

There was a serious performance bug a while back relating to this;
every time SQLite does a COMMIT, this leads to an fsync() call, and
with rather-over-avid use of this, people were seeing Firefox freeze
up for 30 seconds on busy systems.
<https://bugzilla.redhat.com/show_bug.cgi?id=439908>

Someone somewhat validly asks the merits of this:
<http://aplawrence.com/Web/firefox-sqlite.html>

It seems to me that if you want a system that enables wild quantities
of extensions, then it *IS* the right idea to stow all the data in a
DBMS, because that enables the same data to be reused by other
extensions.

But for sure, Firefox has some issues of bloat.  I wonder how much
falls out of the interactions between XML processing, GUI rendering
bits, and Javascript.
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