Memory Leak in `v8::Isolate::New(v8::Isolate::CreateParams const&)`

[Immanuel Haffner]

Hi all,

after upgrading to v8.5.183 the LeakSanitizer of clang detects a memory leak in embedded V8:

==145652==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 12300 byte(s) in 3 object(s) allocated from:

    #0 0x562b902d2ff1 in calloc (/home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/bin/shell+0x11b2ff1)

    #1 0x562b91eb83fe in v8::internal::BasicMemoryChunk::Initialize(v8::internal::Heap*, unsigned long, unsigned long, unsigned long, unsigned long, v8::internal::Space*, v8::internal::VirtualMemory) ../../../../../third-party/v8/v8/src/heap/basic-memory-chunk.cc:31:42

    #2 0x562b90fe3740 in v8::internal::MemoryChunk::Initialize(v8::internal::Heap*, unsigned long, unsigned long, unsigned long, unsigned long, v8::internal::Executability, v8::internal::Space*, v8::internal::VirtualMemory) ../../../../../third-party/v8/v8/src/heap/memory-chunk.cc:176:3

    #3 0x562b90fddaa6 in v8::internal::MemoryAllocator::AllocateChunk(unsigned long, unsigned long, v8::internal::Executability, v8::internal::Space*) ../../../../../third-party/v8/v8/src/heap/memory-allocator.cc:491:7

    #4 0x562b90fdd5a3 in v8::internal::Page* v8::internal::MemoryAllocator::AllocatePage<(v8::internal::MemoryAllocator::AllocationMode)0, v8::internal::PagedSpace>(unsigned long, v8::internal::PagedSpace*, v8::internal::Executability) ../../../../../third-party/v8/v8/src/heap/memory-allocator.cc:617:13

    #5 0x562b91002712 in v8::internal::PagedSpace::Expand() ../../../../../third-party/v8/v8/src/heap/paged-spaces.cc:336:38

    #6 0x562b91005bcf in v8::internal::PagedSpace::RawSlowRefillLinearAllocationArea(int, v8::internal::AllocationOrigin) ../../../../../third-party/v8/v8/src/heap/paged-spaces.cc:974:18

    #7 0x562b910058ba in v8::internal::PagedSpace::SlowRefillLinearAllocationArea(int, v8::internal::AllocationOrigin) ../../../../../third-party/v8/v8/src/heap/paged-spaces.cc:902:10

    #8 0x562b90f2ffea in v8::internal::PagedSpace::AllocateRawUnaligned(int, v8::internal::AllocationOrigin) ../../../../../third-party/v8/v8/src/heap/paged-spaces-inl.h:98:10

    #9 0x562b90f4e53d in v8::internal::Heap::ReserveSpace(std::vector<v8::internal::Heap::Chunk, std::allocator<v8::internal::Heap::Chunk> >*, std::vector<unsigned long, std::allocator<unsigned long> >*) ../../../../../third-party/v8/v8/src/heap/heap.cc:1982:46

    #10 0x562b9204daa6 in v8::internal::DeserializerAllocator::ReserveSpace() ../../../../../third-party/v8/v8/src/snapshot/deserializer-allocator.cc:179:31

    #11 0x562b913d5e31 in v8::internal::ReadOnlyDeserializer::DeserializeInto(v8::internal::Isolate*) ../../../../../third-party/v8/v8/src/snapshot/read-only-deserializer.cc:20:21

    #12 0x562b91007f9e in v8::internal::ReadOnlyHeap::SetUp(v8::internal::Isolate*, v8::internal::ReadOnlyDeserializer*) ../../../../../third-party/v8/v8/src/heap/read-only-heap.cc:119:8

    #13 0x562b90ec89ee in v8::internal::Isolate::Init(v8::internal::ReadOnlyDeserializer*, v8::internal::StartupDeserializer*) ../../../../../third-party/v8/v8/src/execution/isolate.cc:3378:3

    #14 0x562b90ec98ca in v8::internal::Isolate::InitWithSnapshot(v8::internal::ReadOnlyDeserializer*, v8::internal::StartupDeserializer*) ../../../../../third-party/v8/v8/src/execution/isolate.cc:3277:10

    #15 0x562b913f4765 in v8::internal::Snapshot::Initialize(v8::internal::Isolate*) ../../../../../third-party/v8/v8/src/snapshot/snapshot.cc:163:16

    #16 0x562b90d8aaff in v8::Isolate::Initialize(v8::Isolate*, v8::Isolate::CreateParams const&) ../../../../../third-party/v8/v8/src/api/api.cc:8242:8

    #17 0x562b90d8b1ae in v8::Isolate::New(v8::Isolate::CreateParams const&) ../../../../../third-party/v8/v8/src/api/api.cc:8276:3

    #18 0x562b90513208 in db::V8Platform::V8Platform() /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/backend/V8Platform.cpp:198:16

    #19 0x562b9051e429 in std::_MakeUniq<db::V8Platform>::__single_object std::make_unique<db::V8Platform>() /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/10.1.0/../../../../include/c++/10.1.0/bits/unique_ptr.h:961:34

    #20 0x562b9051a26b in db::Backend::CreateWasmV8() /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/backend/V8Platform.cpp:384:42

    #21 0x562b90436e24 in db::Backend::Create(db::Backend::kind_t) /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/tables/Backend.tbl:10:1

    #22 0x562b9032fe6f in db::Backend::Create(char const*) /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/backend/Backend.hpp:27:71

    #23 0x562b9030f065 in process_stream(std::istream&, char const*, db::Diagnostic) /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/shell.cpp:148:32

    #24 0x562b90322319 in main /home/immanuel/Documents/Work/PhD/mutable/mutable/build/debug/../../src/shell.cpp:668:13

    #25 0x7f90097ed001 in __libc_start_main (/usr/lib/libc.so.6+0x27001)

SUMMARY: AddressSanitizer: 12300 byte(s) leaked in 3 allocation(s).

What can I do to help solve this?

Regards,

Immanuel

[Immanuel Haffner]

Build args are

is_clang=true is_component_build=false v8_monolithic=true v8_enable_pointer_compression=false treat_warnings_as_errors=false v8_use_external_startup_data=false use_sysroot=false use_custom_libcxx=false clang_use_chrome_plugins=false target_cpu="x64" is_debug=true use_debug_fission=true

[Immanuel Haffner]

I create an instance with

    v8::Isolate::CreateParams create_params;

    create_params.array_buffer_allocator = allocator_ = v8::ArrayBuffer::Allocator::NewDefaultAllocator();

    isolate_ = v8::Isolate::New(create_params);

and dispose of it with

    isolate_->Dispose();

    delete allocator_;

[Dan Elphick]

Thanks for the report. This may be a bogus report (in that the memory isn't actually leaked) because we use mmap to allocate our memory for MemoryChunks, which means LeakSanitiser doesn't see that there is a connection to the memory pointed to by the MemoryChunk. Alternatively I've created a real leak and this needs addressing.

I'm actively working on this code right now and will take a look at it. It looks like it's related to read-only space sharing which is disabled by pointer compression (which you in turn have disabled), which is probably why our bots missed it.

Thanks,

Dan

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[Immanuel Haffner]

Hey Dan,

thanks for the quick reply. I figured that this is related to pointer compression. I *enabled* pointer compression and the leak is gone.  

Regards,

Immanuel

[Dan Elphick]

I've attempted to reproduce with your sample code and I can't get it to work. I modified samples/hello-world.cc and changed main to this:

int main(int argc, char* argv[]) {
  std::unique_ptr<v8::Platform> platform = v8::platform::NewDefaultPlatform();
  v8::V8::InitializePlatform(platform.get());
  v8::V8::Initialize();
  v8::Isolate::CreateParams create_params;
  auto* allocator_ = create_params.array_buffer_allocator =
      v8::ArrayBuffer::Allocator::NewDefaultAllocator();
  v8::Isolate* isolate_ = v8::Isolate::New(create_params);

  isolate_->Dispose();
  delete allocator_;
  printf("%p\n", malloc(123));
  return 0;
}

built it with "ninja -C out/asan v8_hello_world" and ran it with 

ASAN_OPTIONS=detect_leaks=1 out/asan/v8_hello_world

This shows the memory leak for my spurious malloc but no others. My gn args are the same as the ones you listed except I added is_asan=true. That's probably not quite the same as what you have since this results in a statically linked binary but I'm not sure that would make a difference.

Is there any more detail you could give me? Exact repro code/build steps?

Thanks,

Dan