Hello,
I'm working on a library where multiple threads can run JS code
independently at the same time. In the library, each thread creates and
uses its own Isolate. However, I noticed clang's AddressSanitizer was
complaining about a data race during Isolate creation. I managed to
reproduce the problem outside our library, and I'm sending both the code
and the sanitizer's error message (the code needs to be compiled with
-std=c++11 and -pthread). I'm using V8 5.8.283.38, but I repeated the test
on the master branch and got the same result. What the test does is spawn
10 threads; each one of them just creates and destroys Isolates repeatedly.
I have found a recent issue in the bug tracker [1] that reports a similar
problem, but the commit is not included in V8 5.8, and the problem is
reproducible in the master branch anyway.
So, my question is: I know that multiple threads can run JS code
simultaneously, provided that each thread has its own Isolate; but does
Isolate creation need to be synchronous?
Best regards,
Andre
[1] https://bugs.chromium.org/p/v8/issues/detail?id=5807
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#include <thread>
#include <vector>
#include "v8.h"
#include "libplatform/libplatform.h"
using namespace v8;
const size_t kNumThreads = 10;
const size_t kNumIterations = 1000;
int main() {
V8::InitializeICUDefaultLocation("./v8/out.gn/x64.debug/");
V8::InitializeExternalStartupData("./v8/out.gn/x64.debug/");
Platform* platform = platform::CreateDefaultPlatform();
V8::InitializePlatform(platform);
V8::Initialize();
std::vector<std::thread> threads(kNumThreads);
for (size_t i = 0; i < kNumThreads; ++i) {
threads[i] = std::thread([](){
for (int i = 0; i < kNumIterations; ++i) {
Isolate::CreateParams create_params;
create_params.array_buffer_allocator =
v8::ArrayBuffer::Allocator::NewDefaultAllocator();
Isolate* isolate = Isolate::New(create_params);
{
Isolate::Scope isolate_scope(isolate);
}
delete create_params.array_buffer_allocator;
isolate->Dispose();
}
});
}
for (std::thread &t : threads) {
t.join();
}
V8::Dispose();
V8::ShutdownPlatform();
delete platform;
return 0;
}
==================
WARNING: ThreadSanitizer: data race (pid=19032)
Atomic read of size 1 at 0x7fa59714e078 by thread T9:
#0 pthread_mutex_lock <null> (stress+0x000000439dc5)
#1 v8::base::LockNativeHandle(pthread_mutex_t*)
/home/andre/Develop/v8/v8/out.gn/x64.debug/../../src/base/platform/mutex.cc:57:16
(libv8_libbase.so+0x000000021284)
#2 void std::_Bind_simple<main::$_0 ()>::_M_invoke<>(std::_Index_tuple<>)
/usr/bin/../lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/functional:1390:18
(stress+0x0000004b2cb8)
#3 std::_Bind_simple<main::$_0 ()>::operator()()
/usr/bin/../lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/functional:1380:16
(stress+0x0000004b2c68)
#4 std::thread::_State_impl<std::_Bind_simple<main::$_0 ()> >::_M_run()
/usr/bin/../lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/thread:196:13
(stress+0x0000004b2a9c)
#5 execute_native_thread_routine
/usr/src/debug/gcc-6.3.1-20161221/obj-x86_64-redhat-linux/x86_64-redhat-linux/libstdc++-v3/src/c++11/../../../../../libstdc++-v3/src/c++11/thread.cc:83
(libstdc++.so.6+0x0000000bb5ce)
Previous write of size 1 at 0x7fa59714e078 by thread T8:
#0 pthread_mutex_init <null> (stress+0x00000042580a)
#1 v8::base::InitializeNativeHandle(pthread_mutex_t*)
/home/andre/Develop/v8/v8/out.gn/x64.debug/../../src/base/platform/mutex.cc:23:12
(libv8_libbase.so+0x00000002108e)
#2 void std::_Bind_simple<main::$_0 ()>::_M_invoke<>(std::_Index_tuple<>)
/usr/bin/../lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/functional:1390:18
(stress+0x0000004b2cb8)
#3 std::_Bind_simple<main::$_0 ()>::operator()()
/usr/bin/../lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/functional:1380:16
(stress+0x0000004b2c68)
#4 std::thread::_State_impl<std::_Bind_simple<main::$_0 ()> >::_M_run()
/usr/bin/../lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/thread:196:13
(stress+0x0000004b2a9c)
#5 execute_native_thread_routine
/usr/src/debug/gcc-6.3.1-20161221/obj-x86_64-redhat-linux/x86_64-redhat-linux/libstdc++-v3/src/c++11/../../../../../libstdc++-v3/src/c++11/thread.cc:83
(libstdc++.so.6+0x0000000bb5ce)
Location is global 'v8::base::entropy_mutex' of size 56 at 0x7fa59714e070
(libv8_libbase.so+0x000000034078)
Thread T9 (tid=19042, running) created by main thread at:
#0 pthread_create <null> (stress+0x000000425346)
#1 __gthread_create
/usr/src/debug/gcc-6.3.1-20161221/obj-x86_64-redhat-linux/x86_64-redhat-linux/libstdc++-v3/include/x86_64-redhat-linux/bits/gthr-default.h:662
(libstdc++.so.6+0x0000000bb8e4)
#2 std::thread::_M_start_thread(std::unique_ptr<std::thread::_State,
std::default_delete<std::thread::_State> >, void (*)())
/usr/src/debug/gcc-6.3.1-20161221/obj-x86_64-redhat-linux/x86_64-redhat-linux/libstdc++-v3/src/c++11/../../../../../libstdc++-v3/src/c++11/thread.cc:163
(libstdc++.so.6+0x0000000bb8e4)
#3 main /home/andre/Develop/v8/stress.cc:21:18 (stress+0x0000004b2569)
Thread T8 (tid=19041, running) created by main thread at:
#0 pthread_create <null> (stress+0x000000425346)
#1 __gthread_create
/usr/src/debug/gcc-6.3.1-20161221/obj-x86_64-redhat-linux/x86_64-redhat-linux/libstdc++-v3/include/x86_64-redhat-linux/bits/gthr-default.h:662
(libstdc++.so.6+0x0000000bb8e4)
#2 std::thread::_M_start_thread(std::unique_ptr<std::thread::_State,
std::default_delete<std::thread::_State> >, void (*)())
/usr/src/debug/gcc-6.3.1-20161221/obj-x86_64-redhat-linux/x86_64-redhat-linux/libstdc++-v3/src/c++11/../../../../../libstdc++-v3/src/c++11/thread.cc:163
(libstdc++.so.6+0x0000000bb8e4)
#3 main /home/andre/Develop/v8/stress.cc:21:18 (stress+0x0000004b2569)
SUMMARY: ThreadSanitizer: data race (/home/andre/Develop/v8/stress+0x439dc5) in
pthread_mutex_lock
==================
