C++ Concurrency.

Threads in C++: locks, waiting, atomics, the memory model and data races. Covers 8 topics.

• C++ Concurrency · 1 of 3

  Atomics

  In C++, what does std::atomic<int>::exchange return?

  AThe value held before the callBThe value passed as the argumentCA bool saying whether it changedDThe value held after the call

• C++ Concurrency · 2 of 3

  The thread sanitizer

  Under Apple clang 21.0.0 with -fsanitize=thread and default options, what exit status does a program leave after a data race is reported?

  A1, set by the runtime linkerB0, since main returnedC134, set by the sanitizerD139, from a segmentation fault

• C++ Concurrency · 3 of 3

  The memory model

  Which memory orders does the C++ standard allow on a read-modify-write such as exchange or fetch_add?

  Aany; each half takes what it namesBonly seq_cst is permitted on themConly relaxed is permitted on theseDany; both halves are upgraded to seq_cst