Relaxed Guide to memory_order_relaxed Hans Boehm Paul E. McKenney Google Facebook CPPCON 2020std::atomic/std::atomic_ref and memory_order_relaxed ● C++ atomic operations simple threads-as-interleaving semantics ● by passing memory_order enum values to explicit atomic operations. ● In particular, memory_order_relaxed allows arbitrary visibility reordering with respect memory_order_relaxed? ● Just a load, just a store: Full control, excellent efficiency and scalability! ○ Assuming aligned machine-sized atomic objects, that is…What is Not to Like About memory_order_relaxed

seemingly simple algorithms such as max and min. • We will also discuss the use of operator < in other order-related algorithms, showing how easy it is to make mistakes when using the operator < primitive All rights reserved. 20 An important insight • Given two values a and b, in that order: � Unless we find a reason to the contrary, … � min should prefer to return a, and … � max should min return the same item: � When values a and b are in order, min should return a / max should return b; … � When values a and b are out of order, min should return b / max should return a. 21 Copyright

execution (< 1μs) Low-latency strategy layer (1-10 μs)Order book deep dive “The order book is the heart of any trading system.” Larry Harris 12Order Book In a Nutshell 14 $92 $92 $95 50 $90 100 $85 price” at which you can sell is $92Order Book – Challenges 15 • Latency constraint for algorithmic trading ◦ Remember – it’s not just about being fast to send an order, but being fast to be accurate lowest price - Asks: from lowest to highest price $92 $92 $95 50 $90 100 $85 250 $95 50 $100 75Order Book – Properties 17 • Two ordered sequences - Bids: from highest to lowest price - Asks: from

achieving data determinism via: • Deterministic execution2 will always run computations in the same order. • Deterministic communication2 is when, for a message going from process A to process B, communication deterministic, the ROS application will be in free running mode and could have the impact that the order of messages coming from simulator bridge will not be the same sequence which triggers the running based Apex.Grace constructs related to determinism: 1. Executor management framework 2. Fixed-order execution coordinator based on executor Our proposal© 2023 Apex.AI, Inc. | All rights reserved.

functions and the avoidance of side effects ● Functional programming is identified by the use of higher order functions, pure functions, monads, declarative syntax What is Functional Programming?● A programming functions and the avoidance of side effects ● Functional programming is identified by the use of higher order functions, pure functions, monads, declarative syntax ○ C++ has all the tools to implement functional functions and the avoidance of side effects ● Functional programming is identified by the use of higher order functions, pure functions, monads, declarative syntax ○ C++ has all the tools to implement functional

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 1211 7.7.28 What is the order of executing DML and DDL statements? · · · · · · · · · · 1211 7.7.29 How should I check whether the MySQL variables that TiDB is compatible with? · · · · · · · 5251 15.3.6 The order of results is different from MySQL when ORDER BY is omitted5251 15.3.7 Does TiDB support SELECT FOR UPDATE? · · · · · · automatically collect statistics. In future releases, the priority queue will be the only way to order tasks for automatically collecting statistics, so this system variable will be deprecated. 84 •

MySQL variables that TiDB is compatible with? · · · · · · · 5230 15.3.6 The order of results is different from MySQL when ORDER BY is omitted5230 22 15.3.7 Does TiDB support SELECT FOR UPDATE? · · · · automatically collect statistics. In future releases, the priority queue will be the only way to order tasks for automatically collecting statistics, so this system variable will be deprecated. 79 • fallback action when the memory limit is exceeded #56185 @xzhangxian1008 • Fix the issue that the ORDER BY column in the Sort operator is stuck if it contains a constant #55344 @xzhangxian1008 • Fix the

MySQL variables that TiDB is compatible with? · · · · · · · 5178 15.3.6 The order of results is different from MySQL when ORDER BY is omitted5178 15.3.7 Does TiDB support SELECT FOR UPDATE? · · · · · · automatically collect statistics. In future releases, the priority queue will be the only way to order tasks for automatically collecting statistics, so this system variable will be deprecated. • TiDB idx_col_2 < 20)) #54337 @ghazalfamilyusa • Use index order to avoid extra sorting operations for SQL queries like WHERE idx �→ _col_1 IS NULL ORDER BY idx_col_2 #54188 @ari-e • Display analyzed indexes

MySQL variables that TiDB is compatible with? · · · · · · · 5149 15.3.6 The order of results is different from MySQL when ORDER BY is omitted5149 15.3.7 Does TiDB support SELECT FOR UPDATE? · · · · · · following priority order: status, health, memory, CPU, location, and connection count. • location: the location priority policy performs load balancing based on the fol- lowing priority order: status, location minimum connection count priority policy performs load balanc- ing based on the following priority order: status and connection count. For more information, see documentation. 2.2.1.4 SQL • TiDB supports

template struct atomic_ref { T load(memory_order = memory_order::seq_cst) const noexcept; //... };} namespace sycl { template order DefaultOrder, memory_scope DefaultScope, access Space = access::address_space::generic_space> struct atomic_ref { T load(memory_order order = default_read_order, memory_scope scope = DefaultScope) const noexcept; //... };} ● std::atomic_ref template struct atomic_ref { T load(memory_order = memory_order::seq_cst) const noexcept; //... };} namespace sycl { template order DefaultOrder, memory_scope DefaultScope, access