std::jthread (C++20)

One-Liner

A thread class with built-in RAII semantics — on destruction it automatically sends a stop request and joins, wiping out the 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 parameter receives std::stop_token
Destructor	~jthread()	Requests stop + joins (if joinable)
Request stop	bool request_stop() noexcept	Requests cooperative stop, returns whether it succeeded
Get stop token	std::stop_token get_stop_token() const noexcept	Gets the current thread's stop token
Wait for completion	void join()	Blocks until the thread finishes
Detach thread	void detach()	Detaches; the thread then runs independently
Is joinable	bool joinable() const noexcept	Checks whether the thread is joinable
Get ID	std::thread::id get_id() const noexcept	Returns the 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 in automatically
    // t's destructor automatically calls request_stop() + join()
} // Output: working... stopped

Embedded Applicability: Medium

• The RAII automatic join eliminates the hazard of forgetting to join, improving code robustness.
• The std::stop_token cooperative cancellation mechanism is more disciplined than hand-rolled flag variables.
• Depends on OS thread support; bare-metal RTOS scenarios require a thread abstraction layer alongside it.
• Requires C++20 standard library support; available from 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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