semaphore and mutex feature joined together, is it possible?

[Jun Kusanagi]

Is there any way to solve process synchronization between more than 1
resources.
I'm already trying to use Mutex.WaitAny, but I confused to execute
Release method from the corresponding mutexes.
Any comment will be appreciated.

Best Regards,

 

[William Stacey [MVP]]

Need more info. What are you trying to do.

--
William Stacey [MVP]

| Is there any way to solve process synchronization between more than 1
| resources.
| I'm already trying to use Mutex.WaitAny, but I confused to execute
| Release method from the corresponding mutexes.
| Any comment will be appreciated.
|
| Best Regards,
|

 

[Jun Kusanagi]

Hi William,
thanks for replying, the requirement is:
1. there's 2 resources (R1 & R2), which need to be accessed in a serial
mode
2. access to this resources is coming from 3 different multithreaded
process (P1, P2, P3).
I try to solve this requirement by using mutexes,
P1 using the R1, it locked this resources, so R1 can't be used until P1
is releasing R1.
The question is: by using Mutex.WaitAny for queueing P1, P2, P3
accessing R1 & R2, I can't find out whether R1 or R2 is used, so I
don't know which Mutex to be released. If this kind of requirement
can't be solved by using mutexes, any other brief solution is highly
appreciated.

Best Regards,

 

[William Stacey [MVP]]

Are P1,2,3 actually processes or threads in the same app?

Here is how you might approach it using one mutex to protext both R1 and R2.
// Create Mutex in first P.

Mutex m = new Mutex(false, "mymutex");



// P1,2,3 will get existing mutex and wait on it (timeout recommended), do
work, and release it.

Mutex m1 = Mutex.OpenExisting("mymutex");

m1.WaitOne();

// Use R1 and R2.

m1.ReleaseMutex();


--
William Stacey [MVP]

| Hi William,
| thanks for replying, the requirement is:
| 1. there's 2 resources (R1 & R2), which need to be accessed in a serial
| mode
| 2. access to this resources is coming from 3 different multithreaded
| process (P1, P2, P3).
| I try to solve this requirement by using mutexes,
| P1 using the R1, it locked this resources, so R1 can't be used until P1
| is releasing R1.
| The question is: by using Mutex.WaitAny for queueing P1, P2, P3
| accessing R1 & R2, I can't find out whether R1 or R2 is used, so I
| don't know which Mutex to be released. If this kind of requirement
| can't be solved by using mutexes, any other brief solution is highly
| appreciated.
|
| Best Regards,
|

 

[Jun Kusanagi]

Actually P1, P2, P3 is 3 different application.
Yes, that's what I need, using OpenExisting method to syncrhonize mutex
between different process / application / instance.
Regarding R1 & R2, the problem is each process using whichever
resources available
(R1 / R2), not both. That's why I think it's appropriate to use
WaitAny method for synchronizing resources. The code somehow like
this:

Mutex [] m = new Mutex[2];
m1 = Mutex.OpenExisting("mymutex");
m2 = Mutex.OpenExisting("mymutex2");
m[0] = m1;
m[1] = m2;
// Do error handling

// P1,2,3 will get existing mutex and wait on it (timeout recommended),
do
work, and release it.
//Mutex m1 = Mutex.OpenExisting("mymutex");
//if i changed this code : m1.WaitOne(); to:
Mutex.WaitAny(m);

// Use R1 or R2, whichever available
// here is the part where i confused, if using WaitAny like above,
// how could i know that the one that I used is m1 / m2?
// if using m1 then:
m1.ReleaseMutex();
// else if using m2 then:
m2.ReleaseMutex();

 

[William Stacey [MVP]]

WaitAny returns the index of the mutex that signaled - so that is how you
know which one to release later.

--
William Stacey [MVP]

| // Use R1 or R2, whichever available
| // here is the part where i confused, if using WaitAny like above,
| // how could i know that the one that I used is m1 / m2?
| // if using m1 then:
| m1.ReleaseMutex();
| // else if using m2 then:
| m2.ReleaseMutex();
|

 

[Jun Kusanagi]

yup, that's it, thanks a bunch