ModPagespeed changes cache expiry time of non-rewritten resource to 5 minutes

[David Scherfgen]

Hello,

on my page, I have a CSS resource that's not being rewritten by ModPagespeed. That's OK and to be expected because I'm dynamically adding it using JavaScript.

Since that resource doesn't profit from ModPagespeed, I thought I'd set at least a long cache expiry time in the server configuration:

# ModPagespeed doesn't handle the mobile CSS. Set its cache expiry to one year.

<FilesMatch "^mobile-min\.css$">

Header set Cache-Control "max-age=31556926"

</FilesMatch>

Now when I request that CSS file with ModPagespeed disabled for the site, I get the expected response headers:

1. Accept-Ranges:
   bytes
2. Cache-Control:
   max-age=31556926
3. Connection:
   Keep-Alive
4. Content-Encoding:
   gzip
5. Content-Length:
   1735
6. Content-Type:
   text/css
7. Date:
   Sun, 20 Aug 2017 08:15:09 GMT
8. ETag:
   "bf063-1540-555f2c92a6a40"
9. Keep-Alive:
   timeout=5, max=95
10. Last-Modified:
    Fri, 04 Aug 2017 19:48:49 GMT
11. Server:
    Apache
12. Strict-Transport-Security:
    max-age=63072000; includeSubDomains; preload
13. Vary:
    Accept-Encoding

Whereas with ModPagespeed enabled, I'm getting a cache expiry time of only 5 minutes:

1. Cache-Control:
   max-age=300
2. Connection:
   Keep-Alive
3. Content-Encoding:
   gzip
4. Content-Length:
   1754
5. Content-Type:
   text/css
6. Date:
   Sun, 20 Aug 2017 08:13:14 GMT
7. Etag:
   W/"PSA-aj-VHDXSHSESP"
8. Expires:
   Sun, 20 Aug 2017 08:18:14 GMT
9. Keep-Alive:
   timeout=5, max=100
10. Server:
    Apache
11. Vary:
    Accept-Encoding
12. X-Content-Type-Options:
    nosniff
13. X-Original-Content-Length:
    5440

Do you have any idea why ModPagespeed overwrites my cache expiry time?

Thank you!

[David Scherfgen]

Additional detail: I'm using a ModPagespeedLoadFromFileMatch directive, and it also applies to the CSS resource in question.

Could this be the reason why I'm getting that 5 minutes cache expiry time?

[Otto van der Schaaf]

mod_pagespeed may send out short and conservative caching directives in the header when it is till working to finish computing the fully optimized resource.

If that is the case, you should see the large original expiry value after a couple of refreshes.

(note that images added dynamically via javascript are still processed/optimized by mod_pagespeed's In-Place Resource optimization [1]).

However, I suspect you are running into an issue that I think has been solved in the latest release (1.12.34.2), which involved LoadFromFile and resources that mod_pagespeed can't further improve upon. Upgrading should resolve the issue, or alternatively you could try excluding affected resources from being matched by the LoadFromFile configuration.

[1] https://www.modpagespeed.com/doc/system#ipro

Otto

On Sun, Aug 20, 2017 at 10:35 AM 'David Scherfgen' via mod-pagespeed-discuss <mod-pagesp...@googlegroups.com> wrote:

Additional detail: I'm using a ModPagespeedLoadFromFileMatch directive, and it also applies to the CSS resource in question.

Could this be the reason why I'm getting that 5 minutes cache expiry time?

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[David Scherfgen]

Thanks for the quick response.

I am already using the latest version.

I was able to fix it by adding a "ModPagespeedLoadFromFileRuleMatch Disallow" directive.

[Joshua Marantz]

The resolution you gave works, but also means that mod_pagespeed will not minify the CSS in-place, or optimize any backround image URLs in that CSS.  The reason that your cache-control headers were being ignored is that mod_pagespeed doesn't see them if it loads the resource directly from the file-system.

In 1.12 you can declare the TTL for such resources with

    ModPagespeedLoadFromFileCacheTtlMs implicit_cache_ttl_in_milliseconds

See https://www.modpagespeed.com/doc/system#load_from_file_cache_ttl for details.

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[Luke Kenneth Casson Leighton]

On Sun, Aug 20, 2017 at 9:40 AM, Otto van der Schaaf <osc...@we-amp.com> wrote:

> However, I suspect you are running into an issue that I think has been
> solved in the latest release (1.12.34.2), which involved LoadFromFile and
> resources that mod_pagespeed can't further improve upon.

would symptoms of that involve things from the console like this:

Resources not rewritten because of restrictive Cache-Control headers: 68.81%
Cache misses: 36.22%
Cache lookups that were expired: 16.19%

despite having huge timeouts:

# set file cache ttl (ms) - 7*24*3600*1000
pagespeed LoadFromFileCacheTtlMs 604800000;
pagespeed ImplicitCacheTtlMs 604800000;

[Kevin Nguyen]

pagespeed ImplicitCacheTtlMs 3600000000000;

pagespeed LoadFromFileCacheTtlMs 360000000000;

I had the same issue and finally this works for me. 

[Luke Kenneth Casson Leighton]

On Thu, Aug 31, 2017 at 12:28 PM, Kevin Nguyen
<kevinng...@gmail.com> wrote:

> pagespeed ImplicitCacheTtlMs 3600000000000;
>
> pagespeed LoadFromFileCacheTtlMs 360000000000;
>
>
> I had the same issue and finally this works for me.

ok great i'll give that a shot, thanks kevin