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std::shared_mutex::lock_shared(3) C++ Standard Libary std::shared_mutex::lock_shared(3)


std::shared_mutex::lock_shared - std::shared_mutex::lock_shared


void lock_shared(); (since C++17)

Acquires shared ownership of the mutex. If another thread is holding the mutex in
exclusive ownership, a call to lock_shared will block execution until shared
ownership can be acquired.

If lock_shared is called by a thread that already owns the mutex in any mode
(exclusive or shared), the behavior is undefined.

If more than the implementation-defined maximum number of shared owners already
locked the mutex in shared mode, lock_shared blocks execution until the number of
shared owners is reduced. The maximum number of owners is guaranteed to be at least

A prior unlock() operation on the same mutex synchronizes-with (as defined in
std::memory_order) this operation.



Return value



Throws std::system_error when errors occur, including errors from the underlying
operating system that would prevent lock from meeting its specifications. The mutex
is not locked in the case of any exception being thrown.


lock_shared() is usually not called directly: std::shared_lock is used to manage
shared locking.


This section is incomplete
Reason: no example

See also

lock locks the mutex, blocks if the mutex is not available
(public member function)
tries to lock the mutex for shared ownership, returns if the mutex
try_lock_shared is not available
(public member function)
unlock_shared unlocks the mutex (shared ownership)
(public member function)