# <syncstream>

**[<syncstream>](https://en.cppreference.com/w/cpp/header/syncstream)** provides `std::osyncstream`, a wrapper around `std::ostream` that buffers output and flushes it atomically, preventing interleaved writes from multiple threads (C++20).

Use it when multiple threads write to the same stream and you want each logical message to be atomic.

## Example

This example uses osyncstream from multiple threads to write atomic messages to stdout without interleaving.

```cpp
// compile: g++ -std=c++20 -pthread -o syncstreamexample syncstreamexample.cpp
// run: ./syncstreamexample
// description: synchronized output from multiple threads

#include <syncstream>
#include <iostream>
#include <thread>

int main() {
    std::osyncstream out(std::cout);
    
    auto worker = [](int id) {
        std::osyncstream local(std::cout);
        local << "thread " << id << " message\n";
    };
    
    std::thread t1(worker, 1);
    std::thread t2(worker, 2);
    
    t1.join();
    t2.join();
    
    return 0;
}
```