In V8 why does Isolate::GetCurrent() return NULL?

问题:

I have compiled V8 on Ubuntu and have a very simple V8 program called isolate_test.cc. It is based on the Hello World example from Google:

#include <v8.h> 
using namespace v8;

int main(int argc, char* argv[]) {

    V8::initialize();
    Isolate* isolate = Isolate::GetCurrent(); //Always returns NULL

    return 0; 
}

The command I use to compile this program is:

g++ -Iinclude -g isolate_test.cc -o isolate_test -Wl,--start-group out/x64.debug/obj.target/{tools/gyp/libv8_{base,snapshot},third_party/icu/libicu{uc,i18n,data}}.a -Wl,--end-group -lrt -lpthread

Problem is Isolate::GetCurrent() always returns NULL. Why does this happen and what is the correct way of getting the current Isolate?

I could be way off track but my first thought is that this relates to Isolate::GetCurrent() being unable to get the current thread from libpthread.

Update: As per this question I have added V8::initialize() as the first call in the program, however this does not solve the problem.

回答1:

I have the same issue. I don't really know the underlying reason, but NULL here means default isolate was not created and entered. The obvious workaround is to do it manually

Isolate* isolate = Isolate::GetCurrent(); // returns NULL
if (!isolate) {
    isolate = Isolate::New();
    isolate->Enter();
}

回答2:

The default isolate has been removed from v8. As a result, GetCurrent() is no longer initialized by default.

Here's the issue for the change: https://code.google.com/p/chromium/issues/detail?id=359977