# std::shared_timed_mutex::try_lock_shared_for

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< cpp‎ | thread‎ | shared timed mutex

template< class Rep, class Period > bool try_lock_shared_for( const std::chrono::duration<Rep,Period>& timeout_duration ); |  | (since C++14)

Tries to lock the mutex in shared mode. Blocks until specified `timeout_duration` has elapsed or the shared lock is acquired, whichever comes first. On successful lock acquisition returns true, otherwise returns false.

If `timeout_duration` is less or equal `timeout_duration.zero()`, the function behaves like try_lock_shared().

This function may block for longer than `timeout_duration` due to scheduling or resource contention delays.

The standard recommends that a steady clock is used to measure the duration. If an implementation uses a system clock instead, the wait time may also be sensitive to clock adjustments.

As with try_lock_shared(), this function is allowed to fail spuriously and return false even if the mutex was not locked by any other thread at some point during `timeout_duration`.

Prior unlock() operation on the same mutex synchronizes-with (as defined in std::memory_order) this operation if it returns true.

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

### Parameters

timeout_duration | - | maximum duration to block for

### Return value

true if the lock was acquired successfully, otherwise false.

### Exceptions

Any exception thrown by clock, time_point, or duration during the execution (clocks, time points, and durations provided by the standard library never throw)

### Example

| This section is incomplete Reason: no example

### See also

try_lock_shared | tries to lock the mutex for shared ownership, returns if the mutex is not available (public member function)
try_lock_shared_until | tries to lock the mutex for shared ownership, returns if the mutex has been unavailable until specified time point has been reached (public member function)
try_lock_for | tries to lock the mutex, returns if the mutex has been unavailable for the specified timeout duration (public member function)

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