我写了一个简单的线程池实现,我得到terminate called without an active exception
错误。我已经检查过线程是否可以连接,然后我尝试调试调用析构函数的地方,但没有成功。
workerpool.hpp
#ifndef WORKERPOOL_H
#define WORKERPOOL_H
#include <condition_variable>
#include <iostream>
#include <memory>
#include <mutex>
#include <optional>
#include <queue>
#include <thread>
#include <vector>
class task {
public:
virtual void operator()() = 0;
virtual ~task() = default;
};
class WorkerPool {
private:
class Worker {
private:
std::shared_ptr<WorkerPool> wp;
long id;
public:
Worker(std::shared_ptr<WorkerPool> _wp, long _id) : wp(_wp), id(_id) {
std::cout << "Worker " << id << " created" << std::endl;
};
~Worker() { std::cout << "Worker " << id << " destroyed" << std::endl; }
void operator()() {
while (!wp->stop) {
auto t = wp->fetch_task();
if (!t.has_value())
continue;
else
t.value()->operator()();
}
std::cout << "thread " << id << " ended" << std::endl;
};
};
std::vector<std::thread> workers;
std::queue<std::unique_ptr<task>> q;
std::condition_variable cv;
std::mutex mx;
std::optional<std::unique_ptr<task>> fetch_task() {
std::unique_lock l(mx);
cv.wait(l, [&] { return !q.empty() || stop; });
if (stop)
return {};
auto res = std::move(q.front());
q.pop();
return std::move(res);
};
public:
WorkerPool() {
std::cout << "worker pool created" << std::endl;
for (long i = 0; i < std::thread::hardware_concurrency(); i++) {
workers.push_back(
std::thread(Worker(std::shared_ptr<WorkerPool>(this), i)));
}
}
~WorkerPool() {
std::cout << "worker pool destroyed" << std::endl;
terminate();
for (size_t i = 0; i < workers.capacity(); i++) {
if (workers[i].joinable())
workers[i].join();
}
}
WorkerPool(WorkerPool const &) = delete;
WorkerPool &operator=(WorkerPool const &) = delete;
WorkerPool(WorkerPool &&) = delete;
WorkerPool &operator=(WorkerPool &&) = delete;
bool stop;
void submit(std::unique_ptr<task> t) {
std::lock_guard l(mx);
q.push(std::move(t));
cv.notify_one();
}
void terminate() {
stop = true;
cv.notify_all();
}
};
#endif // WORKERPOOL_H
main.cpp
#include <workerpool.hpp>
#include <condition_variable>
#include <iostream>
#include <mutex>
using namespace std;
class foo : public task {
public:
void operator()() override { cout << "test" << endl; }
};
int main(int argc, char *argv[]) {
WorkerPool wp;
wp.submit(make_unique<foo>());
wp.terminate();
cout << "program ended" << endl;
return 0;
}
控制台输出:
> make run
rm -f bin/*
clang++ -std=c++17 -fuse-ld=lld -pthread -Iinclude -Llib -O2 src/main.cpp -o bin/main
./bin/main
worker pool created
Worker 0 created
Worker 0 destroyed
Worker 0 destroyed
Worker 1 created
Worker 1 destroyed
Worker 1 destroyed
Worker 2 created
Worker 2 destroyed
Worker 2 destroyed
Worker 3 created
Worker 3 destroyed
Worker 3 destroyed
thread 0 ended
Worker 0 destroyed
worker pool destroyed
program endedthread 2 ended
Worker 2 destroyed
worker pool destroyed
worker pool destroyed
terminate called without an active exception
make: *** [Makefile:32: run] Aborted (core dumped)
std::shared_ptr<WorkerPool>(this)
你不能这样做。你告诉shared_ptr
它拥有该对象,但事实并非如此。它的生命周期已在其他地方管理(在这种情况下,在main
的“堆栈”)。
因此,你显然最终得到了双重删除(通知2ד工作人员池被破坏”)。在形式上,结果是未定义的,特别是当你为每个工作线程创建更多无关的shared_ptr
s时:如果程序没有崩溃,我打赌你已经看到4×那条线。
有办法使这成为可能,using enable_shared_from_this
,虽然that cannot work in the constructor(因为“原始”shared_ptr
将不会完成所有权)。