Thanks Leif! These comments were really helpful.
We've upgraded to version 10 and tweaked the dir entry memory to 32KB. 1.8TB cache disk, partitioned into 5 cache volumes 8KB min_average_object_size: memory util 2.9GB 32KB min_average_object_size: memory util 665.2m 1800GB_32KB:"proxy.process.cache.volume_1.direntries.total": "12491400", 1800GB_8KB:"proxy.process.cache.volume_1.direntries.total": "49872896", Woot woot! Awesome. Significant memory saved for our workload. stale-while-revalidate is also a huge win! On Sat, Apr 20, 2024 at 12:12 PM Leif Hedstrom <apachezw...@gmail.com> wrote: > > > On Apr 19, 2024, at 21:42, dave seddon <dave.seddon...@gmail.com> wrote: > > > Thanks Brian! Very cool > > I don't know if you're supposed to retroactively update release notes, but > that's a pretty big feature not in the notes. > > > https://docs.trafficserver.apache.org/en/10.0.x/release-notes/upgrading.en.html > > > Yeh the release notes for 10.x are not done yet. > > Stale-while-revaldate feature was a major challenge for some of our use > cases, so it's awesome to hear that is resolved. Congratulations and thank > you! > > A potentially larger challenge is memory footprint. Generally, for Yahoo, > Apple, Comcast CDNs, and all you guys all have beefy machines with plenty > of RAM, so this isn't a drama. In those scenarios ATS is an amazing > solution! Woot woot. Love it! > > There are more unique situations, home caching for example, where you want > large amounts of cache storage, but much lower in memory indexes to that > storage. > > I'm not suggesting ATS needs to solve is, but, for the sake of the mailing > list history, people need to keep in mind. > > Specifically, and unless I'm mistaken, RAM consumption is directly linear > with the available cache size, regardless of the "working set". > > E.g. If you have a large storage you need a (relatively) large amount of > RAM to index into that storage, even if most of the storage is not accessed. > > > Well, yes. However it’s 10x less memory than e.g. squid for the same disk > cache size :). The cost is 10 bytes of memory per directory entry (index). > > Now, you can, and should, tune the number of directory entries to your > data set. The default is pretty conservative, one dir entry for every 8KB > of disk cache. If your average object size is noticeably larger than this > (very likely), you can reduce memory usage accordingly. So setting this > configuration to 16KB would reduce memory use in half, 32KB is 1/4 memory > etc. > > Cheers, > > — Leif > > > Again, this is a totally understandable engineering decision, and makes > sense in most situations. > > On Fri, Apr 19, 2024, 14:02 Brian Neradt <brian.ner...@gmail.com> wrote: > >> If I understand correctly, ATS does NOT support stale while revalidate, >>> which is surprising given the RFC was created by a Yahoo-ligan. ;) >>> >> >> I'm glad you mentioned this. Actually Yahoo open-sourced the >> functionality for stale while revalidate via the stale_response.so plugin >> for ATS 10: >> >> >> https://docs.trafficserver.apache.org/en/latest/admin-guide/plugins/stale_response.en.html#stale-response-plugin >> >> On Fri, Apr 19, 2024 at 3:38 PM dave seddon <dave.seddon...@gmail.com> >> wrote: >> >>> Depending on your use case, you also want to carefully consider the >>> cache control headers for the downloaded object. >>> >>> If I understand correctly, ATS does NOT support stale while revalidate, >>> which is surprising given the RFC was created by a Yahoo-ligan. ;) >>> >>> On Fri, Apr 19, 2024 at 9:51 AM Leif Hedstrom <zw...@apache.org> wrote: >>> >>>> We discussed this in the slack channel. Probably the best option for >>>> you (other than writing a new plugin) is to use the background_fetch >>>> plugin. You will still need to trigger a download, but you can avoid having >>>> to wait for the full response in the client. So, what you’d do is >>>> >>>> curl -H “Range: bytes=0-1” >>>> https://www.example.com/some/url/foo.img >>>> >>>> >>>> And make sure background_fetch is enabled on this remap rule. No matter >>>> what you do, you will have to have something that tells ATS to kick off a >>>> download, and the above is probably as good as any alternative. >>>> >>>> Cheers, >>>> >>>> — Leif >>>> >>>> >>>> On Apr 17, 2024, at 9:33 AM, Pavel Vazharov <pa...@x3me.net> wrote: >>>> >>>> Hi Brian, >>>> >>>> Thank you for your response. >>>> It'll do the job but, as far as I understand it, an external >>>> functionality will need to download the content in order to push it into >>>> the ATS. >>>> The content that I want to write in the ATS storage is on the Internet. >>>> >>>> Regards, >>>> Pavel. >>>> >>>> On Wed, Apr 17, 2024 at 6:26 PM Brian Neradt <brian.ner...@gmail.com> >>>> wrote: >>>> >>>>> Hi Pavel, >>>>> >>>>> This isn't a direct answer to your question, but are you aware of the >>>>> ATS HTTP PUSH feature? That allows you to push objects into the ATS cache >>>>> without the typical caching of proxied response. Can that help you in this >>>>> situation? >>>>> >>>>> >>>>> https://docs.trafficserver.apache.org/en/latest/admin-guide/configuration/cache-basics.en.html#pushing-content-into-the-cache >>>>> >>>>> >>>>> On Wed, Apr 17, 2024 at 8:41 AM Pavel Vazharov <pa...@x3me.net> wrote: >>>>> >>>>>> Hi there, >>>>>> >>>>>> Is there a way to use the ATS as an HTTP client to download and store >>>>>> given content? >>>>>> I'm aware that I can achieve this with a local HTTP client (wget, >>>>>> curl) which uses the ATS as a forward proxy and then the ATS will store >>>>>> the >>>>>> content (which is the actual goal). >>>>>> I was wondering if there is a way without using an additional HTTP >>>>>> client so that I can skip the additional content moving between sockets. >>>>>> >>>>>> Thanks, >>>>>> Pavel. >>>>>> >>>>> >>>>> >>>>> -- >>>>> "Come to Me, all who are weary and heavy-laden, and I will >>>>> give you rest. Take My yoke upon you and learn from Me, for >>>>> I am gentle and humble in heart, and you will find rest for >>>>> your souls. For My yoke is easy and My burden is light." >>>>> >>>>> ~ Matthew 11:28-30 >>>>> >>>> >>>> >>> >>> -- >>> Regards, >>> Dave Seddon >>> +1 415 857 5102 >>> >> >> >> -- >> "Come to Me, all who are weary and heavy-laden, and I will >> give you rest. Take My yoke upon you and learn from Me, for >> I am gentle and humble in heart, and you will find rest for >> your souls. For My yoke is easy and My burden is light." >> >> ~ Matthew 11:28-30 >> > -- Regards, Dave Seddon +1 415 857 5102
