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

Question

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.

See http://stackoverflow.com/questions/16924087/segfault-in-v8-on-windows-in-handlescope-constructor , you're probably missing a call to V8::initialize(); , which is probably also a documentation bug in the examples — nos, May 23 '14 at 09:15
I can't find any reference to `V8::initialize()` - has it been removed from the API? — donturner, May 23 '14 at 09:20
Not entirely sure, though it's defined in the file of your link to [Isolate::GetCurrent()](https://code.google.com/p/v8/codesearch#v8/trunk/src/api.cc&q=Isolate%3a%3aGetCurrent%28%29&sq=package%3av8&l=6523) — nos, May 23 '14 at 09:30

Peter K · Accepted Answer · 2014-06-23T13:37:04.893

3

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();
}

edited Jun 23 '14 at 13:37

answered Jun 23 '14 at 13:08

Peter K

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15

score 3 · Answer 2 · answered Nov 17 '15 at 21:19

3

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

answered Nov 17 '15 at 21:19

eh9

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43

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

2 Answers2

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