© 2020 Bloomberg Finance L.P. All rights reserved. Retiring the Singleton Pattern Concrete suggestions for what to use instead CppCon 2020 September 18, 2020 Peter Muldoon Senior Software DeveloperBloomberg

Bad_Speculation,Retiring –p pidRunning perf on a benchmark 46 • First perf measurements should never be too specific perf stat –I 10000 –M Frontend_Bound,Backend_Bound,Bad_Speculation,Retiring –p pid Source: should never be too specific perf stat –I 10000 –M Frontend_Bound,Backend_Bound,Bad_Speculation,Retiring –p pid # counts unit events 43194329517 de_src_op_disp.all:u # 25.0 % bad_speculation 13998678938 ls_not_halted_cyc:u # 26.4 % retiring 22162353234 ex_ret_ops:u 15111861755 de_no_dispatch_per_slot.backend_stalls:u

– Maged Michael Occasionally objects in a cohort’s reclaimableObjects_ list are reclaimed when retiring objects to the cohort (by a related thread). • Pop all objects from domain cohort object list shards deprecated. Still supported for testing and microbenchmarking. • 2020: One user: High frequency of retiring objects. Unsharded list grew out of control. • 2020: Sharded cohorts without reclamation under lock

Std:move_only_function example https://godbolt.org/z/d56PYe4vo - be my own mock Godbolt listings124 Bloomberg Retiring The Singleton Pattern : Concrete Suggestions on What to Use Instead Redesigning Legacy Systems :

determined by catch functionality) • Preferably using only the OmegaException class102 Bloomberg Retiring The Singleton Pattern : Concrete Suggestions on What to Use Instead Redesigning Legacy Systems :

serve this �→ country: Justice Stephen Breyer—an Army veteran, Constitutional �→ scholar, and retiring Justice of the United States Supreme Court. �→ Justice Breyer, thank you for your service. One serve this �→ country: Justice Stephen Breyer—an Army veteran, Constitutional �→ scholar, and retiring Justice of the United States Supreme Court. �→ Justice Breyer, thank you for your service. One serve this �→ country: Justice Stephen Breyer—an Army veteran, Constitutional �→ scholar, and retiring Justice of the United States Supreme Court. �→ Justice Breyer, thank you for your service. One

serve this �→ country: Justice Stephen Breyer—an Army veteran, Constitutional �→ scholar, and retiring Justice of the United States Supreme Court. �→ Justice Breyer, thank you for your service. One serve this �→ country: Justice Stephen Breyer—an Army veteran, Constitutional �→ scholar, and retiring Justice of the United States Supreme Court. �→ Justice Breyer, thank you for your service. One serve this �→ country: Justice Stephen Breyer—an Army veteran, Constitutional �→ scholar, and retiring Justice of the United States Supreme Court. �→ Justice Breyer, thank you for your service. One

life to serve this country: Justice �→ Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the �→ United States Supreme Court. Justice Breyer, thank you for your service. One life to serve this country: Justice �→ Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the �→ United States Supreme Court. Justice Breyer, thank you for your service. One life to serve this country: Justice �→ Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the �→ United States Supreme Court. Justice Breyer, thank you for your service. One

life to serve this country: Justice �→ Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the �→ United States Supreme Court. Justice Breyer, thank you for your service. One life to serve this country: Justice �→ Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the �→ United States Supreme Court. Justice Breyer, thank you for your service. One life to serve this country: Justice �→ Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the �→ United States Supreme Court. Justice Breyer, thank you for your service. One