Found similar questions: Is it safe to `delete this`?
I know that it's unsafe to access member variable. Because this becomes a dangling pointer after delete. But what about stack variable？Clang ASAN does report error if member variable is accessed. But it does not report any problems about stack variable access.
IMHO. Stack is destroyed after the current execution thread is finished. So it is probably safe to access stack variable even if this is deleted. Is there any better solution in this scenario? Following is the test case.
#include <atomic>
#include <chrono>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <ratio>
#include <string>
#include <system_error>
#include <thread>
#include <vector>
std::mutex g_iostream_mutex;
class TestDeleteBase {
int task_num_ = 0;
std::atomic<int> counter_;
public:
virtual void Run() = 0;
void Init(int task_num) {
task_num_ = task_num;
counter_.store(0, std::memory_order_relaxed);
}
void RunParallel() {
int local = counter_;
if (counter_.fetch_add(1, std::memory_order_acq_rel) == task_num_ - 1) {
delete this;
{
std::lock_guard<std::mutex> guard(g_iostream_mutex);
std::cout << std::this_thread::get_id() << " deleted this\n";
}
return;
} else {
{
std::lock_guard<std::mutex> guard(g_iostream_mutex);
std::cout << std::this_thread::get_id() << " not delete \n";
}
std::this_thread::sleep_for(std::chrono::seconds(1));
}
{
std::lock_guard<std::mutex> guard(g_iostream_mutex);
std::cout << std::this_thread::get_id() << " Access " << local << '\n';
std::cout << std::this_thread::get_id() << " Still alive\n";
}
}
virtual ~TestDeleteBase() {}
};
class TestDelete : public TestDeleteBase {
void Run() override {}
};
int main(int argc, char* argv[]) {
TestDeleteBase* obj = new TestDelete();
obj->Init(5);
std::vector<std::thread> threads;
for (int i = 0; i < 5; ++i) {
threads.emplace_back(&TestDeleteBase::RunParallel, obj);
}
for (auto&& thread : threads) {
thread.join();
}
}
