1518256 - Cache is more than 0 bytes after clear & restart

Status: RESOLVED INVALID

(Firefox :: Settings UI, defect)

Description

[aruseni]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:64.0) Gecko/20100101 Firefox/64.0

Steps to reproduce:

1. Delete ~/.mozilla
2. Open Firefox
3. Open Preferences
4. In Home, change Homepage and new windows to Blank Page
5. In Privacy & Security, uncheck Allow Firefox to send technical and interaction data to Mozilla
6. Click Clear History…
7. Click Clear Now
8. Restart Firefox
9. Open Preferences
10. In Privacy & Security, the following is displayed:
    Your stored cookies, site data and cache are currently using 2.0 kB of disc space.

Actual results:

Cache is 2.0 kB.

Expected results:

Expected cache size is 0 bytes (since no web pages were open after browser restart).

Now, if you restart the browser another time, cache size is going to be 4.0 kB, i.e. it is increased after each restart by 2.0 kB.

This is not always reproducible. If you repeat this experiment a few times, the cache can be, as expected, 0 bytes.

Comment 1

[Matthias Versen [:Matti]]

What is shown in about:cache (List of Entries) ?

Comment 2

[aruseni]

I have repeated the mentioned steps, and also disabled search suggestions (because otherwise the cache is filled very quickly as you type about:cache). Please see the attached screenshots (nothing is shown in about:cache).

Comment 3

[aruseni]

Attachment: Preferences

Comment 4

[aruseni]

Attachment: about:cache

Comment 5

[:Gijs (he/him)]

I don't see any reason to want to fix this. I do see things in about:cache, notably the snippets cache, various blocklist bits and pieces (like HTTPS cert pinning info, and soon more detailed cert intermediate information, add-on blocklist info, etc.).

The fact that it's not possible to navigate to about:preferences fast enough before we've made an effort to re-sync such things 100% of the attempts isn't really a bug.

Comment 6

[aruseni]

I don’t have anything in about:cache, yet in preferences the cache size is more than 0 bytes. To me, it clearly is a bug.

Comment 7

[aruseni]

As far as I understand, you haven’t really tried to reproduce it (I have specifically mentioned running Firefox without .mozilla in your home directory, so it is created for you). Please see if you can do it, and if you will still have different result, I can record a screencast to show it to you.

Comment 8

[:Gijs (he/him)]

(In reply to aruseni from comment #7)

As far as I understand, you haven’t really tried to reproduce it (I have specifically mentioned running Firefox without .mozilla in your home directory, so it is created for you)

I used a clean profile ( https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles ) , which does the same thing.

I tried at least 5 times, and each time I got more than 2kb, and I got entries in about:cache . Waiting another 5 minutes after startup, there were even more entries in about:cache .

(In reply to aruseni from comment #6)

To me, it clearly is a bug.

What, exactly, is the bug, in your eyes?

Comment 9

[:Gijs (he/him)]

OK, so after also disabling snippets on the new tab page, I could reproduce.

However, the issue is caused by the fact that we cache OCSP responses anonymously - so for OCSP checks on network connections for things like update checks, that response is stored in cache. If you tick 'anonymous' on about:cache and click 'update', you do see these entries, which match up to cache being used. That means this isn't a bug, just confusing UI in about:cache. As about:cache is meant for internal use, I don't think we should worry about it.

Comment 10

[aruseni]

OK, thank you for clearing this out, now it certainly makes sense. Let’s hope anybody else wondering about how it happens will be able to Google it. Have a nice day.