VolatileRead Method (Single)

Thread.VolatileRead Method (Single)


Reads the value of a field. The value is the latest written by any processor in a computer, regardless of the number of processors or the state of processor cache.

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

Public Shared Function VolatileRead (
	ByRef address As Single
) As Single


Type: System.Single

The field to be read.

Return Value

Type: System.Single

The latest value written to the field by any processor.

VolatileRead and VolatileWrite are for special cases of synchronization. Under normal circumstances, the C# lock statement, the Visual Basic SyncLock statement, and the Monitor class provide easier alternatives.

On a multiprocessor system, VolatileRead obtains the very latest value written to a memory location by any processor. This might require flushing processor caches.

Even on a uniprocessor system, VolatileRead and VolatileWrite ensure that a value is read or written to memory, and not cached (for example, in a processor register). Thus, you can use them to synchronize access to a field that can be updated by another thread, or by hardware.

Calling this method affects only a single memory access. To provide effective synchronization for a field, all access to the field must use VolatileRead or VolatileWrite.


In C#, using the volatile modifier on a field guarantees that all access to that field uses VolatileRead or VolatileWrite.

.NET Framework
Available since 1.1
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