BUILT-IN MATHEMATICA SYMBOL

CriticalSection

locks the variables

with respect to parallel computation, evaluates expr, then releases the

.

At most one instance of a critical section with the same lock variable is allowed to run concurrently on any parallel kernel.

Protect a block of code from interference by other threads:

Without protecting access to the update code, subkernels may overwrite results:

Protect a block of code from interference by other threads:

Out[2]=

Without protecting access to the update code, subkernels may overwrite results:

Out[3]=

Lock variables can be of the form

:

Separate read and write operations are not thread-safe:

Use CriticalSection to make a whole code section atomic:

Locks are acquired by writing the kernel's ID into the lock variable:

Shared functions can be used for synchronization in place of a critical section:

Less efficient is the use of a shared variable and critical section:

Lock variables must not have a value before being used in a critical section:

A deadlock can be broken with an abort:

The dining philosophers, deadlock-free: