Status: New
Owner: ----
New issue 3374 by [email protected]: A compatibility problem of v8`s
default isolate
http://code.google.com/p/v8/issues/detail?id=3374
I use the newest code in the trunk of v8, and I found a core dump, when I
execute the hello_world program in the
link "https://developers.google.com/v8/get_started";.
I think it is a compatibility problem.
The reason of core dump is analyzed as below:
In hello_world.cc, the code is:
// Get the default Isolate created at startup.
Isolate* isolate = Isolate::GetCurrent(); // --here is the problem
// Create a stack-allocated handle scope.
HandleScope handle_scope(isolate);
// Create a new context.
Handle<Context> context = Context::New(isolate);
when i debug the core dump file, i found the pointer of "isolate" is a null
pointer.
Program received signal SIGSEGV, Segmentation fault.
0x0000000000414883 in v8::HandleScope::Initialize (this=0x7fffffffe3c0,
isolate=0x0) at ../src/api.cc:572
572 prev_next_ = current->next;
(gdb) bt
#0 0x0000000000414883 in v8::HandleScope::Initialize (this=0x7fffffffe3c0,
isolate=0x0) at ../src/api.cc:572
#1 0x0000000000414805 in v8::HandleScope::HandleScope
(this=0x7fffffffe3c0, isolate=0x0) at ../src/api.cc:557
#2 0x0000000000403871 in main ()
(gdb) p current
$1 = (v8::internal::HandleScopeData *) 0x3530
(gdb)
By analyzing, I found that it caused by the modify of
function "EnsureDefaultIsolate".
The process of default isolate is changed, and in the new version, there
will not be a default isolate,
so the functin "Isolate::GetCurrent()" will return a NULL pointer.
This problem will make those software that based on old v8 version unusable
when they update to a new version.
At last the code:
In the old release version of V8:
void Isolate::EnsureDefaultIsolate() {
LockGuard<Mutex> lock_guard(&process_wide_mutex_);
CHECK(default_isolate_status_ != kDefaultIsolateCrashIfInitialized);
if (default_isolate_ == NULL) {
isolate_key_ = Thread::CreateThreadLocalKey();
thread_id_key_ = Thread::CreateThreadLocalKey();
per_isolate_thread_data_key_ = Thread::CreateThreadLocalKey();
#ifdef DEBUG
PerThreadAssertScopeBase::thread_local_key =
Thread::CreateThreadLocalKey();
#endif // DEBUG
thread_data_table_ = new Isolate::ThreadDataTable();
default_isolate_ = new Isolate();
}
// Can't use SetIsolateThreadLocals(default_isolate_, NULL) here
// because a non-null thread data may be already set.
if (Thread::GetThreadLocal(isolate_key_) == NULL) {
Thread::SetThreadLocal(isolate_key_, default_isolate_);
}
}
And in the newest code:
void Isolate::EnsureDefaultIsolate() {
LockGuard<Mutex> lock_guard(&process_wide_mutex_);
CHECK(default_isolate_status_ != kDefaultIsolateCrashIfInitialized);
if (default_isolate_ == NULL) {
isolate_key_ = Thread::CreateThreadLocalKey();
thread_id_key_ = Thread::CreateThreadLocalKey();
per_isolate_thread_data_key_ = Thread::CreateThreadLocalKey();
#ifdef DEBUG
PerThreadAssertScopeBase::thread_local_key =
Thread::CreateThreadLocalKey();
#endif // DEBUG
thread_data_table_ = new Isolate::ThreadDataTable();
}
}
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