c++ - Two threads modifying same object at same time -


in simple server-client mechanism i'm writing, server stores set of key-value mappings in stl map. talking multiple clients, separate thread created each, , i've passed map threads using std::ref (i need common keystore). while works, possible that:

1) if 2 clients communicate @ same time, 2 threads try modify map @ same time?

2) in case, happen?

3) possibly avoid bad?

1) if 2 clients communicate @ same time, 2 threads try modify map @ same time?

yes, try modify @ same time

2) in case, happen?

you have undefined behavior. can happen.

3) possibly avoid bad?

use std::lock_guard avoid problem. can refer link more details: http://en.cppreference.com/w/cpp/thread/lock_guard


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