How do I use v8 in a thread?

Question

I'm trying to use v8 from c++ inside a thread that isn't the main thread. There's no multi-threading as far as v8 is concerned, all v8 objects are created and destroyed within that thread. Nothing is running in parallel, nothing is being shared. When I run my program from the main thread, everything works fine. When I have the v8 stuff in another thread, I get segmentation fault when I create a v8::HandleScope.

I can't find any useful documentation on how threading is actually addressed with v8. The instruction "use isolates and lockers" pops up often when searching, but I can't find any examples on how this is done. There's this API doc on v8::Isolate, but nothing on that page tells me if I need them in my specific case (I'm not sharing memory or executing in parallel). The docs on v8::Locker() don't even have information about what the class is for. The included samples in the project don't deal with any of this either.

So my questions are...

• Do I need to use isolates and/or lockers here?
• Could I get a minimal example of how to use them? Even pseudo-code or something would be really useful

Answer 1

You do need V8::Locker in the methods that will be working with the context when calling HandleScope. https://github.com/jasondelponte/go-v8/blob/master/src/v8context.cc#L41 is an example of how I've use the locker with v8. In this example it is used with multiple threads, but I believe the rule applies with single threads also.

Isolates are only needed when you want multiple instances of v8 in parallel.

https://groups.google.com/forum/?fromgroups=#!topic/v8-users/FXpeTYuAqKI Is an old thread I found a bit ago that helped me solve my problem with the library crashing as soon as HandleScope local variable was created.