ThreadPool,

https://docs.microsoft.com/ru-ru/dotnet/standard/threading/the-managed-thread-pool

https://docs.microsoft.com/ru-ru/dotnet/api/system.threading.threadpool?view=net-6.0

https://professorweb.ru/my/csharp/thread_and_files/1/1_16.php

https://ru.stackoverflow.com/questions/1063446/%D0%9A%D0%B0%D0%BA-%D1%80%D0%B0%D0%B1%D0%BE%D1%82%D0%B0%D0%B5%D1%82-%D0%BF%D1%83%D0%BB-%D0%BF%D0%BE%D1%82%D0%BE%D0%BA%D0%BE%D0%B2

https://habr.com/ru/post/654101/

https://habr.com/ru/post/654111/

http://dir.by/developer/csharp/thread_pooling/

https://studassistent.ru/charp/pul-potokov-c

http://veb.name/index.php?document=pul_potokov_v_C

https://www.youtube.com/watch?v=6LxCtwtHAZo

https://github.com/Infarh/InstanceThreadPool