# std::shared_lock<Mutex>::try_lock_for

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< cpp‎ | thread‎ | shared lock

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

Tries to lock the associated mutex in shared mode. Blocks until specified `timeout_duration` has elapsed or the lock is acquired, whichever comes first. On successful lock acquisition returns true, otherwise returns false. Effectively calls mutex()->try_lock_shared_for(timeout_duration).

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.

std::system_error is thrown if there is no associated mutex or if the mutex is already locked.

The behavior is undefined if `Mutex` does not meet the SharedTimedLockable requirements.

### Parameters

timeout_duration | - | maximum duration to block for

### Return value

true if the ownership of the mutex has been acquired successfully, false otherwise.

### Exceptions

- Any exceptions thrown by mutex()->try_lock_shared_for(timeout_duration)

- If there is no associated mutex, std::system_error with an error code of std::errc::operation_not_permitted

- If the mutex is already locked, std::system_error with an error code of std::errc::resource_deadlock_would_occur

### Example

| This section is incomplete Reason: no example

### See also

try_lock_for | attempts to lock (i.e., takes ownership of) the associated TimedLockable mutex, returns if the mutex has been unavailable for the specified time duration (public member function of `std::unique_lock<Mutex>`)
lock | locks the associated mutex (public member function)
try_lock | tries to lock the associated mutex (public member function)
try_lock_until | tries to lock the associated mutex, until a specified time point (public member function)
unlock | unlocks the associated mutex (public member function)

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