SOFTWARE OR THE USE OR OTHER DEALINGS IN THE // SOFTWARE. Lockfree, MPMC Queue - Legal CppCon 2024 | Erez Strauss | Lockfree, MPMC Queue https://github.com/erez-strauss/lockfree_mpmc_queueAbout me ● C++/C com/in/erezstrauss/ 3 CppCon 2024 | Erez Strauss | Lockfree, MPMC Queue https://github.com/erez-strauss/lockfree_mpmc_queueLockfree, MPMC Queue - Agenda 1. Trading Platform, Latency 2. Queues Environment 5. Queues Classification 6. Queue creation, push, pop 7. Queue internals 8. Testing 9. Performance - Benchmarking 4 CppCon 2024 | Erez Strauss | Lockfree, MPMC Queue https://github.com/erez-strau

We need a system Orchestrator to implement the robot behaviorRobot Behaviors This Coordinator or Task Planner is also the highest level of abstraction of our system, where we focus on WHAT the robot

used when we created them.” - Albert EinsteinSo what is there to Rethink?Rethinking: Task Queues Problem #1 - Task Queues Do Not Scale Well: ● Contention: ○ Even the most meticulously designed lock-free problems: ○ Task starvation ○ Load balancing ○ Forfeits strict FIFO behaviour ○ Increases memory footprint (or requires allocations) ○ Terrible task selection “fairness” Task Thread Thread Thread Task Task Task Task Task Task Task Task Back Front Task Queue Execute Task() Thread Thread PoolRethinking: Task Queues Problem #2 - No Inherent Support For Prioritization: ● Priority queues address this but

in a top-down task graph What is Task Graph-based Programming System (TGPS) Code 4• TGPS encapsulates function calls and their dependencies in a top-down task graph What is Task Graph-based Programming top-down task graph What is Task Graph-based Programming System (TGPS) Code A B C D B A C D 6• TGPS encapsulates function calls and their dependencies in a top-down task graph What is Task Graph-based sched; 2 task_a = sched.emplace([](&){ 3 // Code block A; 4 }); 5 task_b = sched.emplace([](&){ 6 // Code block B; 7 }); 8 task_c = sched.emplace([](&){ 9 // Code block C; 10 }); 11 task_d = sched

understanding the general behavior only. template struct task; task sum(int a, int b) { int result = a + b; co_return result; } task sum4(int a, int b, int c, int d) { int ab = co_await initial_suspend_awaitable_t initial_suspend_awaitable; final_suspend_awaitable_t final_suspend_awaitable; }; }; task sum(int a, int b) { auto frame = make_unique<__sum_frame>(a, b); decltype(auto) returnObject release())); return returnObject; } template struct task; task sum(int a, int b) { int result = a + b; co_return result; } task sum4(int a, int b, int c, int d) { int ab = co_await

org/projects/tornado/downloads/]. User’s guide Introduction Asynchronous and non-Blocking I/O Coroutines Queue example - a concurrent web spider Structure of a Tornado web application Templates and UI Authentication patterns Calling blocking functions Parallelism Interleaving Looping Running in the background Queue example - a concurrent web spider Structure of a Tornado web application The main coroutine The Application asynchronous interfaces: Callback argument Return a placeholder (Future, Promise, Deferred) Deliver to a queue Callback registry (e.g. POSIX signals) Regardless of which type of interface is used, asynchronous

interfaces: • Callback argument • Return a placeholder (Future, Promise, Deferred) • Deliver to a queue • Callback registry (e.g. POSIX signals) Regardless of which type of interface is used, asynchronous await nxt # Wait for the timer to run out. 6.1.4 Queue example - a concurrent web spider Tornado’s tornado.queues module (and the very similar Queue classes in asyncio) implements an asynchronous producer Python standard library’s queue module. A coroutine that yields Queue.get pauses until there is an item in the queue. If the queue has a maximum size set, a coroutine that yields Queue.put pauses until there

projects, etc. ● Our brains (i.e., human cpus) however tend to perform best when we can focus on one task at a time ○ (e.g., I am unable to code and listen to music with any lyrics...unfortunately) Thinking machines So--does our hardware support concurrency? Yes! Each core can be working on a separate task. (Note: A single core can also handle concurrency)(Quick Examples) X-Box One ● Yes, the hardware threads work with data? 681000 threads working together (1/4) 69 ● Assume you have some shared task: ○ Perhaps 1000 threads counting the sizes of files in a directory to find the total bytes of the

accessors, ... private: T* storage_; }; 1 2 3 4 5 6 7 8Queue template class Queue { public: Queue& Push(const T& element); ElementContainer Pop(); private: use-case of Queue class TaskQueue { public: Add(OnceCallback task) { task_queue_.Push(std::move(task)); } private: void Run() { while (true) { std::move(task_queue_.Pop()).Run(); Run(); } } ThreadSafeQueue> task_queue_; }; 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Outlook and Future Work Early results show that TaskQueue can pass tasks between threads with

31 2.3.3 C++ COM API . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.3.4 Event queue processing . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 2.3.5 Visual Basic and Visual h file in the glue layer. 2.3.4 Event queue processing Both VirtualBox client programs and frontends should periodically perform processing of the main event queue, and do that on the application’s main using VirtualBox cannot directly control the main event loop and the main event queue is separated from the event queue of the programming librarly (for example in case of Qt on Unix platforms). In such