Embedded Google v8 memory leak with sample - c++

Question

I'm trying to embed V8 but I have some memory leaks. The following minimal code reproduce the leaks.
int main(int argc, char* argv[])
{
// V8 version 7.1.302.33
v8::V8::InitializeICUDefaultLocation(argv[0]);
v8::V8::InitializeExternalStartupData(argv[0]);
std::unique_ptr<v8::Platform> platform = v8::platform::NewDefaultPlatform();
v8::V8::InitializePlatform(platform.get());
v8::V8::Initialize();
v8::Isolate::CreateParams create_params;
create_params.array_buffer_allocator = v8::ArrayBuffer::Allocator::NewDefaultAllocator();
v8::Isolate* pIsolate = v8::Isolate::New(create_params); // If I remove this line and the next one, memory leak disappears
pIsolate->Dispose();
v8::V8::Dispose();
v8::V8::ShutdownPlatform();
delete create_params.array_buffer_allocator;
}
With this code, my visual studio 2017 print theses leaks in the output
Detected memory leaks!
Dumping objects ->
{5565} normal block at 0x000001BA6F417950, 8 bytes long.
Data: < i > 00 00 E8 69 18 00 00 00
{5564} normal block at 0x000001BA6F416960, 16 bytes long.
Data : <8 >o > 38 D7 3E 6F BA 01 00 00 00 00 00 00 00 00 00 00
{5563} normal block at 0x000001BA6F3ED720, 56 bytes long.
Data: < >o > o > A0 D6 3E 6F BA 01 00 00 A0 D6 3E 6F BA 01 00 00
{989} normal block at 0x000001BA6F4194E0, 128 bytes long.
Data: < >o > o > A0 D6 3E 6F BA 01 00 00 A0 D6 3E 6F BA 01 00 00
{988} normal block at 0x000001BA6F416CD0, 16 bytes long.
Data: < p ` > 70 B4 60 0A FF 7F 00 00 00 00 00 00 00 00 00 00
{987} normal block at 0x000001BA6F417270, 16 bytes long.
Data : < X ` > 58 B4 60 0A FF 7F 00 00 00 00 00 00 00 00 00 00
{986} normal block at 0x000001BA6F3ED6A0, 56 bytes long.
Data : < >o > o > 20 D7 3E 6F BA 01 00 00 20 D7 3E 6F BA 01 00 00
Object dump complete.
So do you know what I forget ?
Thanks in advance for your help ;)

Answer 1

I copied your code, and ran it on linux environment, with -fsanitize=address flag setted, didn't get any memory leak error.

Answer 2

Here a dirty workaround to remove most memory leaks.
You have to redefine the internal class IsolateAllocator to call private function FreeProcessWidePtrComprCageForTesting().
A first way by adding a new function Free() to be able to call the private function.
namespace v8::internal
{
class IsolateAllocator
{
public:
static void Free() { FreeProcessWidePtrComprCageForTesting(); }
private:
static void FreeProcessWidePtrComprCageForTesting();
};
} // namespace v8::internal
or without adding a function to IsolateAllocator, but using a friend class like it's done in v8 unit test (I just rename the friend class).
namespace v8::internal
{
class IsolateAllocator
{
private:
friend class SequentialUnmapperTest;
static void FreeProcessWidePtrComprCageForTesting();
};
class SequentialUnmapperTest
{
public:
static void Free() { IsolateAllocator::FreeProcessWidePtrComprCageForTesting(); }
};
} // namespace v8::internal
Call the Free() function before v8::V8::Dispose();:
isolate->Dispose();
v8::internal::IsolateAllocator::Free();
v8::V8::Dispose();
v8::V8::ShutdownPlatform();
delete create_params.array_buffer_allocator;
There is still few memory leak due to call v8::V8::InitializeICUDefaultLocation() (which do some allocation using when calling udata_setCommonData()) and other due to base::LazyInstance<std::weak_ptr<CodeRange>>::type process_wide_code_range_ in code-range.cc which store a std::weak_ptr<> which is never destroyed...