For now, switching to ICU was reverted.  Nonetheless, we need to make a switch eventually to fix v8:6031, v8:2137, v8:6076 (and other bugs). 

As for your case:  can you do something like this ?

https://cs.chromium.org/chromium/src/content/zygote/zygote_main_linux.cc?rcl=f21e201655b13db8d51873070f24c3c65bd378f2&l=400

 That is, before sandbox kicks in in your render process, you can call icu::TimeZone::createDefault(). createDefault() can read TZ and honor its value (because sandbox does not yet start). 

>  v8:6031, v8:2137, v8:6076
 bug v8:6031 ,  bug v8:2137 , bug v8:6076

I don't think that would be enough. Zygote has already started, so changing timezone in the browser process explicitly will not affect the zygote - it will still run with the host's timezone. To make it work the linked line should somehow "ask" TZ from the main process instead of detecting it itself.

For clarity - we are talking about changing TZ in runtime without changing TZ of the hosting system.

> For clarity - we are talking about changing TZ in runtime without changing TZ of the hosting system.

That was a missing piece to me. Thanks for the clarification. 

> Zygote has already started,so changing timezone in the browser process explicitly will not affect the zygote 

Yes, true. BTW, the code referred to in comment 1 is run in 'the' zygote process (as its filename implies), but once it's run at the start of the zygote process, a subsequent change in timezone does not affect the zygote process. 

Anyway, this bug is essentially the same as  bug 612010  except that timezone monitor does not monitor TZ change. So, fixing  bug 612010  and triggering timezone change event when you change TZ should work, shouldn't it? 

Correct, fixing the bug about propagating timezone changes to zygote + honouring TZ changes in the monitor will do the trick.

That said I'm not sure I can think of an efficient way of monitoring TZ variable without polling...

+Ali, this may affect Node.js.

This seems to have come back after https://chromium-review.googlesource.com/c/v8/v8/+/857333.

 bug 612010  was fixed by crrev.com/ecc9a74e8a6642d . Timezone monitor still does not monitor TZ change.  However, when a new render process is forked, the ICU timezone will be updated if TZ has changed since. 

So, this issue is fixed for new render process, while running render processes wouldn't respond to a change in TZ.