Designing an ultra low-overhead multithreading runtime for Nim Mamy Ratsimbazafy mamy@numforge.co Weave https://github.com/mratsim/weave Hello! I am Mamy Ratsimbazafy During the day blockchain/Ethereum refactoring of the internals 3 Agenda ◇ Understanding the design space ◇ Hardware and software multithreading: definitions and use-cases ◇ Parallel APIs ◇ Sources of overhead and runtime design ◇ Minimum threads -> N hardware threads The same distinctions can be done at a multithreaded language or multithreading runtime level. The problem 8 How to schedule M tasks on N hardware threads? Latency vs

categories) ❏ Modern C++ Data Types (move semantics) ❏ CsString library (unicode) ❏ Multithreading in C++ ❏ Multithreading using libGuarded ❏ Signals and Slots ❏ Templates in the Real World ❏ What’s in ● CsString Library ○ standalone unicode aware string library ● CsLibGuarded ○ standalone multithreading library for shared data 46Applications ● KitchenSink ○ contains 30 demos and links with almost

char8_t ❏ Multithreading in C++ ❏ Modern C++ Threads ❏ C++ Memory ModelPresentations - www.youtube.com/copperspice ❏ Why CopperSpice, Why DoxyPress ❏ Compile Time Counter ❏ Multithreading using CsLibGuarded ● CsString Library ○ standalone unicode aware string library ● CsLibGuarded ○ standalone multithreading library for shared data 52Libraries ● CsCrypto ○ C++ interface to the Botan and OpenSSL libraries

2.7 starts in 54s ◉ Stellaris 2.8 beta starts in 21s ◉ Same amount of work ◉ Both rely on multithreading 112.7 (Old) Startup CPU Usage2.8 (New) Startup CPU UsageStartup Breakdown ◉ Enumerate asset tracks from zips ◉ Can we optimize unzip() further? ◉ PhysFS still has a lock per archive, so multithreading might be tricky 67Loading audio ◉ How many music tracks do we need to display loading screen

AbstractMonitoringInterceptor * fixed DebugInterceptor to properly synchronize access to its count field in a multithreading environment Package org.springframework.beans * BeanWrapperImpl keeps registered editors in fixed ResponseTimeMonitorImpl to properly synchronize access to its instance variables in a multithreading environment Package org.springframework.web * used NestedServletException wherever a root cause ManagedList and ManagedMap resolution for prototypes in AbstractBeanFactory * fixed potential multithreading issue on nested prototype resolution in AbstractBeanFactory * dependent beans (with corresponding

AbstractMonitoringInterceptor * fixed DebugInterceptor to properly synchronize access to its count field in a multithreading environment Package org.springframework.beans * BeanWrapperImpl keeps registered editors in fixed ResponseTimeMonitorImpl to properly synchronize access to its instance variables in a multithreading environment Package org.springframework.web * used NestedServletException wherever a root cause ManagedList and ManagedMap resolution for prototypes in AbstractBeanFactory * fixed potential multithreading issue on nested prototype resolution in AbstractBeanFactory * dependent beans (with corresponding

AbstractMonitoringInterceptor * fixed DebugInterceptor to properly synchronize access to its count field in a multithreading environment Package org.springframework.beans * BeanWrapperImpl keeps registered editors in fixed ResponseTimeMonitorImpl to properly synchronize access to its instance variables in a multithreading environment Package org.springframework.web * used NestedServletException wherever a root cause ManagedList and ManagedMap resolution for prototypes in AbstractBeanFactory * fixed potential multithreading issue on nested prototype resolution in AbstractBeanFactory * dependent beans (with corresponding

getCount()" accessor * fixed DebugInterceptor to properly synchronize access to its count field in a multithreading environment Package org.springframework.beans * factored out extended PropertyAccessor and fixed ResponseTimeMonitorImpl to properly synchronize access to its instance variables in a multithreading environment Package org.springframework.validation * added further accessors to Errors interface:

getCount()" accessor * fixed DebugInterceptor to properly synchronize access to its count field in a multithreading environment Package org.springframework.beans * factored out extended PropertyAccessor and fixed ResponseTimeMonitorImpl to properly synchronize access to its instance variables in a multithreading environment Package org.springframework.validation * added further accessors to Errors interface:

getCount()" accessor * fixed DebugInterceptor to properly synchronize access to its count field in a multithreading environment Package org.springframework.beans * factored out extended PropertyAccessor and fixed ResponseTimeMonitorImpl to properly synchronize access to its instance variables in a multithreading environment Package org.springframework.validation * added further accessors to Errors interface: