170066 - Using RAM Disk for cache (Mac OS classic)

Status: VERIFIED WONTFIX

(Core :: Networking: Cache, defect, P2)

Description

[Mike]

Configuration:
Mozilla rv 1.1 build: Mozilla/5.0 #20020824
Using a bondi-iMac REV A, with system 9.1, 128Mb RAM
site where problem occurs: www.foxnews.com

I have set up a 10Mb RAM Disk that I use exclusively as the disk cache for
Mozilla.I have the disk cache size set to 9Mb in the Mozilla preferences. I have
Mozilla set to compare at each visit to a page.

After several days of normal surfing, I'll read a news article on the above
site, and then when I return to the main page using the Mozilla back button a
blank page loads. If I use the "clear disk chche" button in the prefs panel the
page loads normaly and at a speed consistent with the use of the cache.

Comment 1

[Henri Sivonen (:hsivonen)]

What's the point in putting the disk cache on a RAm disk instead of disabling
the disk cache and using Mozilla's internal RAM cache only?

Comment 2

[Jo Hermans]

The Mac RAM Disk is persistent (it isn't wiped out by a restart), and a lot
faster than a regular disk. It's great for data that needs fast access, but
that's not so important. If the whole computer locks up, your RAM disk isn't
saved on to the hard disk, and you got back to the state of the RAM disk before
you booted. That's not too bad for a cache.

I think it's a more general cache-bug, and it has nothing to do with a RAM disk.
Mozilla doesn't know the difference anyway. The cache-file might have been
damaged somehow.

Comment 3

[Boris Zbarsky [:bzbarsky]]

confirming to get this investigated... I bet we ignore the "9MB" limit, run into
the size limit of the ramdisk, and corrupt the cache...

Comment 4

[Jo Hermans]

See also bug 142069 (cache uses more memory than configured, because of
file-system issues)

Comment 5

[gordon]

What happens when you try shift-reload on the blank page (before clearing the
cache).  I'm trying to determine if the cache is corrupted or if a single cache
entry is bad.

Comment 6

[gordon]

*** Bug 196866 has been marked as a duplicate of this bug. ***

Comment 7

[benc]

gordon: should we WONTFIX this because it is a CFM bug?

Solaris is the only other OS I know of that liberally uses memory mapped disk
space (/tmp is RAM in most default configs), but it wouldn't suffer from this
problem because the partion allocation is dynamic.

Comment 8

[benc]

RESOLVED/WONTFIX:
CFM is RIP.

The disk cache overflow bugs are clearly documented elsewhere, but this config
is not supported.

Comment 9

[Frankie]

v