TryEnter Method (Object, TimeSpan, Boolean)

Monitor.TryEnter Method (Object, TimeSpan, Boolean)


Attempts, for the specified amount of time, to acquire an exclusive lock on the specified object, and atomically sets a value that indicates whether the lock was taken.

Namespace:   System.Threading
Assembly:  mscorlib (in mscorlib.dll)

public static void TryEnter(
	object obj,
	TimeSpan timeout,
	ref bool lockTaken


Type: System.Object

The object on which to acquire the lock.

Type: System.TimeSpan

The amount of time to wait for the lock. A value of –1 millisecond specifies an infinite wait.

Type: System.Boolean

The result of the attempt to acquire the lock, passed by reference. The input must be false. The output is true if the lock is acquired; otherwise, the output is false. The output is set even if an exception occurs during the attempt to acquire the lock.

Exception Condition

The input to lockTaken is true.


The obj parameter is null.


The value of timeout in milliseconds is negative and is not equal to Infinite (–1 millisecond), or is greater than MaxValue.

If the value of the timeout parameter converted to milliseconds equals –1, this method is equivalent to Enter(Object). If the value of timeout equals 0, this method is equivalent to TryEnter(Object).

If the lock was not taken because an exception was thrown, the variable specified for the lockTaken parameter is false after this method ends. This allows the program to determine, in all cases, whether it is necessary to release the lock.


Use Monitor to lock objects (that is, reference types), not value types. For more information, see Enter and the conceptual topic Monitors.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Available since 4.0
Windows Phone Silverlight
Available since 7.1
Windows Phone
Available since 8.1
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