Editing Modula-3 (section)

===Multi-threaded===
The language supports the use of multi-threading, and synchronization between threads.
There is a standard module within the [[runtime library]] (''m3core'') named Thread, which supports the use of multi-threaded applications. The Modula-3 runtime may make use of a separate thread for internal tasks such as garbage collection.

A built-in data structure <code>[[Lock (computer science)|MUTEX]]</code> is used to synchronize multiple threads and protect data structures from simultaneous access with possible corruption or race conditions. The <code>LOCK</code> statement introduces a block in which the mutex is locked. Unlocking a <code>MUTEX</code> is implicit by the code execution locus's leaving the block. The <code>MUTEX</code> is an object, and as such, other objects may be derived from it.

For example, in the [[input/output]] (I/O) section of the library ''libm3'', readers and writers (Rd.T, and Wr.T) are derived from MUTEX, and they lock themselves before accessing or modifying any internal data such as buffers.
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