Hi Mark, Thanks for getting in touch! I'm not familiar with Android WebView, so I'll let someone else comment on that topic. Regarding file: URLs, I believe that the problem is that file: URLs don't use the network cache. This seems sort of obvious, I guess: caching a file from a local disk on the same local disk would waste space and not speed anything up. However, when requests use the network cache, servers have the opportunity to respond with "304 Not Modified". When the browser receives that response, it can be confident in reusing code cache data from a previous load. See also the "Don't change code" section in "Code caching for JavaScript developers" <https://v8.dev/blog/code-caching-for-devs#don%E2%80%99t-change-code>. Otherwise, the browser has no clear guarantee that the newly loaded file matches what it loaded previously, so it must re-parse.
file: URLs are not the only script loads that suffer from lack of code caching because they bypass the network cache. Last year, I worked on a feature to enable code caching for WebUI scripts. WebUI refers to web pages provided by the browser itself rather than a remote server, such as the History page or the Downloads popup. The feature is still disabled by default due to underwhelming results when we enabled it for a small percentage of users, but I hope to get time (eventually...) to return to it and improve performance. I suspect that the documents and code reviews related to that feature work might help point you in the right direction regarding scripts loaded by file: URLs or WebViews. Everything is linked from this bug: Extend V8 code caches to WebUI scripts <https://bugs.chromium.org/p/chromium/issues/detail?id=1210399>. Best, Seth On Monday, June 27, 2022 at 8:28:35 AM UTC-7 Egor Pasko wrote: > +v8-dev (take 2) > > On Sat, Jun 4, 2022 at 12:37 AM Mark Meeus <mark....@gmail.com> wrote: > >> Hi Everyone, >> >> I'm trying to figure out why chromium is not using script compilation >> cache when the script loaded from a page served by file:// (and not at all >> in an Android WebView) >> >> I am testing with this html: >> <html><head></head> >> <body> >> <script src="https://code.jquery.com/jquery-3.6.0.js";></script> >> </body></html> >> >> When serving this page over* file://* => performance profiler reports: >> >> *Streamed: true* >> *Compilation cache status: script not eligible* >> >> When serving over *http:// * >> >> *Streamed: false: script has code-cache available* >> *Compilation cache status: script loaded from cache* >> *Compilation cache: size127 kB* >> >> >> Having observed this behaviour with the Chromium profiling tool, I would >> like to trace it back in the Chromium source code. >> >> It's the first time I'm looking at Chromium code, and it's a bit >> overwhelming :-) >> >> I'm thinking the ScriptCacheConsumer would be involved, but a breakpoint >> in it's constructor doesn't seem to get hit when loading the page over http. >> The ScriptStreamer::ScriptDecoder DidReveiveData triggers on a >> breakpoint, even when the compilation cache is used. >> >> >> We have a pretty large javascript app which we also run on Android >> WebView, we could have a huge benefit from compiled script cache. On >> Android however, the script cache isn't always working on pages served over >> https either (script not eligible). >> >> So I'm actually searching for the code that decides wether a script is >> eligible or not for the code caching. >> Could anyone point me in the right direction? >> >> kind regards, >> Mark >> >> -- >> -- >> Chromium Developers mailing list: chromi...@chromium.org >> View archives, change email options, or unsubscribe: >> http://groups.google.com/a/chromium.org/group/chromium-dev >> --- >> You received this message because you are subscribed to the Google Groups >> "Chromium-dev" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to chromium-dev...@chromium.org. >> To view this discussion on the web visit >> https://groups.google.com/a/chromium.org/d/msgid/chromium-dev/9fe77bd9-f4da-4b1d-a9ea-f5d701d72b6en%40chromium.org >> >> <https://groups.google.com/a/chromium.org/d/msgid/chromium-dev/9fe77bd9-f4da-4b1d-a9ea-f5d701d72b6en%40chromium.org?utm_medium=email&utm_source=footer> >> . >> > > > -- > Egor Pasko > -- -- v8-dev mailing list v8-dev@googlegroups.com http://groups.google.com/group/v8-dev --- You received this message because you are subscribed to the Google Groups "v8-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to v8-dev+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/v8-dev/4b53796e-21e8-4d9f-a118-bf1578b339f3n%40googlegroups.com.
