Problem Statement

A mutex (abbreviated Mutually Exclusive access) is a synchronization object, a variant of semaphore with k=1. A mutex is said to be seized by a task decreasing k. It is released when the task restores k. Mutexes are typically used to protect a shared resource from concurrent access. A task seizes (or acquires) the mutex, then accesses the resource, and after that releases the mutex. A mutex is a low-level synchronization primitive exposed to deadlocking. A deadlock can occur with just two tasks and two mutexes (if each task attempts to acquire both mutexes, but in the opposite order). Entering the deadlock is usually aggravated by a race condition state, which leads to sporadic hangups, which are very difficult to track down.

Let's start with the solution:

import: parallel

: job(mut)
   mut receive drop
   "I get the mutex !" .
   2000 sleep
   "Now I release the mutex" println
   1 mut send drop ;  
 
: mymutex
| mut |
   Channel new dup send(1) drop ->mut
   10 #[ #[ mut job ] & ] times ;