The Unlock command releases the lock on the mutex with identifier mutexId.  The thread evaluating the call to Unlock should have previously acquired the lock by calling the Lock command.

For more information on using mutexes, see the Mutex help page.

p := proc( m )
   global count;
   print( count );
   count := count+1;
end proc;

$p≔\mathbf{proc}\left(m\right)\mathbf{global}\mathrm{count}\;\mathrm{print}\left(\mathrm{count}\right)\;\mathrm{count}≔\mathrm{count}\+1\mathbf{end\; proc}$

$\mathrm{count}≔1$

$\mathrm{count}≔1$

$\mathrm{Threads}\left[\mathrm{Wait}\right]\left(\mathrm{seq}\left(\mathrm{Threads}\left[\mathrm{Create}\right]\left(p\left(m\right)\right)\,i=1..10\right)\right)$

$1$

$2$

$3$

$4$

$5$

$6$

$6$

$8$

$8$

$10$

p := proc( m )
   global count;
   Threads[Mutex][Lock]( m );

   print( count );
   count := count+1;

   Threads[Mutex][Unlock]( m );
end proc;

$p≔\mathbf{proc}\left(m\right)\mathbf{global}\mathrm{count}\;\mathrm{Threads}\[\mathrm{Mutex}\]\[\mathrm{Lock}\]\left(m\right)\;\mathrm{print}\left(\mathrm{count}\right)\;\mathrm{count}≔\mathrm{count}\+1\;\mathrm{Threads}\[\mathrm{Mutex}\]\[\mathrm{Unlock}\]\left(m\right)\mathbf{end\; proc}$

$\mathrm{count}≔1$

$\mathrm{count}≔1$

$m≔\mathrm{Threads}\left[\mathrm{Mutex}\right]\left[\mathrm{Create}\right]\left(\right)$

$m≔1$

$\mathrm{Threads}\left[\mathrm{Wait}\right]\left(\mathrm{seq}\left(\mathrm{Threads}\left[\mathrm{Create}\right]\left(p\left(m\right)\right)\,i=1..10\right)\right)\:$

$1$

$2$

$3$

$4$

$5$

$6$

$7$

$8$

$9$

$10$

$\mathrm{Threads}\left[\mathrm{Mutex}\right]\left[\mathrm{Destroy}\right]\left(m\right)$