2013/11/19 Yuras Shumovich
[...] but I see only one not trivial difference with my code. I'm creating isolate manually, and you are using the default one. Check that Isolate::GetCurrent() returns anything. I can imaging that your code is running in unbound green thread, or it is bound to OS thread other then the main one. v8 use thread local storage, that can be the issue.
Yes, v8 uses TLS to store the current Isolate (= VM instance) for historical reasons, and if you want to use the default Isolate (created even before main() is entered) things get tricky if you are not using it from the main thread. Furthermore, if you use an Isolate from various threads (sequentially, re-entry is not allowed) you have to use v8's Locker to tell v8 what's happening. Isolate::Scope has to be used to tell v8 when you are switching between several Isolates in a single thread. This is all sub-optimal (<- huge understatement) and we regret the introduction of TLS in v8 every single day, it is a constant source of bugs, confusion and complexity. Having said that, we are currently in the process of removing TLS and make the Isolate very explicit in v8's API. But this is easier said than done, given all the various complex embedders v8 has (Chrome, node.js, ...). In a bright future, v8 uses no TLS, all Isolates are explicit, there is no default Isolate and no "current Isolate", and Isolate::Scope and Locker are merged. Until then things are a bit tricky, but you can make your life easier by building a debug version of v8, which has tons of assertions, making stuff like a NULL Isolate blindingly obvious. Choosing a combination of 2 multi-threaded runtimes for learning purposes has a slightly masochistic touch... ;-)