Isn't that one of the issues nowadays, that people have the attitude "we have enough memory" and thus don't tend to care about optimizing for memory usage anymore.

Your suggested solution, about discarding when memory is needed, solves this problem. But it solves a problem that would be created by needlessly storing a lot more data than needed. So it's a solution to a problem that was not a problem to begin with.

But I know, if it's a few kb, it will not make a huge difference.

No this is really not the case of thinking we have enough memory. This is the realization that the static source code of a page is a percentage error compared to the memory overhead of a rendered page. The modern browser are memory hog I would rather they focus on that.

Its also a broken implementation function wise since I have asked for the source of the current page not of a reload.

100kb * 100 tabs is 10MB. I'll take my chances.

So hide it behind a feature flag?

> "we have enough memory"

Your phone is in disagreement.

We're talking about a default feature which is disabled 'for average users'. Average users only have a few tabs open in their browser. Not 100. Average users also don't have 3 GB RAM, nor do they use view source on a mobile phone, and neither do average users actually use the feature. So the default setting makes sense even though a user who is using the feature may end up using several MB due to a reload (not cool on a plan).

If you are saving 57 kB per tab open, that'd be ~5,7 MB with 100 tabs open. But if you have 100 tabs open on a mobile phone (!!), you have a bigger problem, and all those tabs are causing swapping already anyway. In that sense, enabling the feature by default makes sense. And don't forget that some people don't have flat rate internet.

My phone has a quite insane 3 GB of RAM.

My phone also has the insane 3GB of RAM, but last week Chrome killed Spotify and vice versa (music stopped playing) as soon as I switched apps. Sadly 3GB is not enough for Android and todays apps.

The most common $150 phone from last year only has 1GB, half of which is reserved for the OS.

Similar "tab discarding" feature already exists in Chrome, by the way:

https://developers.google.com/web/updates/2015/09/tab-discar...

> So, the browser should load the HTML page into a part of memory that can be discarded by the OS if the OS needs more memory. Actually I think it is strange that no such memory API exists in Unix.

It is more tricky then you would think to determine what "needed" memory means. Does the OS need disk cache? Or the content of memory mapped files?

It's not unlikely that you currently have some process active which has memory mapped a huge file. Does it need the content? Who knows.

You are talking about an OS-provided cache for the browser to store it's own cache in? There's little sense in that.

Moving memory management into the OS often makes sense, because the OS has the big cross-application picture, knows the system-wide memory pressure, and most importantly, already manages the memory of applications, by swapping between RAM and disk.

For the same reason, OS X and Android Linux both have systems for OS managed caches, and AFAIK Firefox already uses these: https://bugzilla.mozilla.org/show_bug.cgi?id=748598

The status on mainline Linux is a bit more nebulous (seems Android's ashmem has been upstreamed, but it's not directly usable on GNU/Linux systems?), and other efforts have stranded: https://lwn.net/Articles/602650/

For some more thoughts about memory management on OS level vs. application level, I can recommend this "random outburst" from the designer of the Varnish HTTP cache: https://www.varnish-cache.org/docs/trunk/phk/notes.html