Is it safe to read an integer variable that's being concurrently modified without locking?

Question

Suppose that I have an integer variable in a class, and this variable may be concurrently modified by other threads. Writes are protected by a mutex. Do I need to protect re

Answer 1

Both reading / writing to variables with concurrency must be protected by a critical section (not mutex). Unless you want to waste your whole day debugging.

Critical sections are platform-specific, I believe. On Win32, critical section is very efficient: when no interlocking occur, entering critical section is almost free and does not affect overall performance. When interlocking occur, it is still more efficient, than mutex, because it implements a series of checks before suspending the thread.