std::jthread (C++20)

In a Nutshell

A thread class with built-in RAII semantics—automatically sends a stop request and joins on destruction, eliminating crashes caused by forgetting to join.

Header

#include <thread>

Core API Cheat Sheet

Operation	Signature	Description
Construct (with function)	template<class F> jthread(F&& f, Args&&... args)	Starts a new thread executing f(args...)
Construct (with stop_token)	template<class F> jthread(F&& f)	f's first argument receives std::stop_token
Destructor	~jthread()	Requests stop + join (if joinable)
Request stop	bool request_stop() noexcept	Requests cooperative stop, returns success status
Get stop token	std::stop_token get_stop_token() const noexcept	Gets the current thread's stop token
Wait for completion	void join()	Blocks waiting for thread to finish
Detach thread	void detach()	Detaches, thread runs independently
Is joinable	bool joinable() const noexcept	Checks if thread is joinable
Get ID	std::thread::id get_id() const noexcept	Returns thread identifier

Minimal Example

// Standard: C++20
#include <iostream>
#include <thread>

void worker(std::stop_token st) {
    while (!st.stop_requested()) {
        std::cout << "working...\n";
    }
    std::cout << "stopped\n";
}

int main() {
    std::jthread t(worker); // 自动传入 stop_token
    // t 析构时自动 request_stop() + join()
} // 输出: working... stopped

Embedded Applicability: Medium

• RAII automatic join eliminates the risk of forgetting to join, improving code robustness.
• std::stop_token cooperative cancellation mechanism is more standardized than manual flag variables.
• Relies on OS thread support; bare-metal RTOS scenarios require a thread abstraction layer.
• Requires C++20 standard library support; available in GCC 10+, but Clang/libc++ support came later (17+).

Compiler Support

GCC	Clang	MSVC
10	17	19.28

See Also

• cppreference: std::jthread
• cppreference: std::stop_token

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