std::jthread (C++20)

In a Nutshell

A thread class with built-in RAII semantics — on destruction it automatically sends a stop request and joins, eliminating crashes from forgotten joins.

Header

#include <thread>

Core API Quick Reference

Operation	Signature	Description
Construct with function	template<class F> jthread(F&& f, Args&&... args)	Start 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()	Request stop + join (if joinable)
Request stop	bool request_stop() noexcept	Request cooperative stop, returns success
Get stop token	std::stop_token get_stop_token() const noexcept	Get the thread's stop token
Wait for completion	void join()	Block until thread finishes
Detach thread	void detach()	Detach; thread runs independently
Is joinable	bool joinable() const noexcept	Check if thread can be joined
Get ID	std::thread::id get_id() const noexcept	Return 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); // stop_token is passed automatically
    // t destructor calls request_stop() + join() automatically
} // Output: working... stopped

Embedded Applicability: Medium

• RAII auto-join eliminates the risk of forgotten joins, improving robustness
• std::stop_token cooperative cancellation is more disciplined than hand-rolled flag variables
• Requires OS thread support; bare-metal RTOS scenarios need a threading abstraction layer
• Requires C++20 standard library support; GCC 10+ works, 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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