 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
.NET Forum / .NET Framework / New Users / October 2006Global Semaphore problems
Hi, I'm trying to syncronize access to a shared resource between processes using system semaphores. The processes are spawned by Cruise Control.Net. I use OpenExisting,and if that fails I catch the exception and use new Semaphore( name ); The problem is that OpenExisting always fails, even though the other process has created the semaphore. The CCNET service is running as a domain user. Any ideas? Thanks Andy > I'm trying to syncronize access to a shared resource between processes > using system semaphores. Do you want mutually exclusive access? I think Mutex would be a better option... Nnot sure about how you have created the first semaphore.. does the original thread has the ownership during creation? What is the count? What is the upper limit?  SignatureHappy Hacking, Gaurav Vaish | www.mastergaurav.com www.edujinionline.com http://eduzine.edujinionline.com ----------------------------------------- Gaurav, Yes, I wanted mutally exclusive access. However, no matter what I did, the second process would throw an AbandonedMutexException when it returned from WaitOne. I think I did figure this out though; I now have a static variable to hold onto the semaphore after the first nant task I wrote completes. Then the second one attempts to access that static variable. This seems to keep the semaphore from being GCed under a CCNET environment. Don't know why it worked as my user and not under CCNET, but keeping a reference to the semaphore makes it work under CCNET as well. FWIW, I did try this same static refrence trick with the Mutex, but it always resulted in an AbandonedMutexException. Andy > > I'm trying to syncronize access to a shared resource between processes > > using system semaphores. [quoted text clipped - 14 lines] > http://eduzine.edujinionline.com > ----------------------------------------- Oh, to answer your questions.. Initial count was 1, max count was one. I didn't see anyway to owner ship of a semaphor, I don't think it supports that concept. In my aquireLock i used new Semaphore( 1, 1, LockName ); In my releaseLock I used OpenExisting.. Andy > > I'm trying to syncronize access to a shared resource between processes > > using system semaphores. [quoted text clipped - 14 lines] > http://eduzine.edujinionline.com > ----------------------------------------- > Initial count was 1, max count was one. I didn't see anyway to owner > ship of a semaphor, I don't think it supports that concept. My fault... ownership is in the case of Mutex.. :D Regarding your case... not sure but I think you earlier had a, probably, local variable or a instance-field that got garbage-collected somewhere down the line and hence, Semaphore being abandoned. SignatureHappy Hacking, Gaurav Vaish | www.mastergaurav.com www.edujinionline.com http://eduzine.edujinionline.com ----------------------------------------- > Regarding your case... not sure but I think you earlier had a, probably, > local variable or a instance-field that got garbage-collected somewhere down > the line and hence, Semaphore being abandoned. Semaphores don't seem to care about being abandoned. Did you mean Mutex? I'm not sure that was the problem either, because I held a static reference to the mutex so that a single nant process didn't lose the reference until the AppDomain ended.. Releasing the mutex woudl work find as it would use that static reference, but the other process still threw the exception. Oh well, it works now, that's all I care about. Andy > Releasing the mutex woudl work find as it would use that static > reference, but the other process still threw the exception. Oh well, > it works now, that's all I care about. Hmm... all's well that ends well. Probably, I'll put this "interesting" study in my blog. Let me also try to reproduce it here... :) SignatureHappy Hacking, Gaurav Vaish | www.mastergaurav.com www.edujinionline.com http://eduzine.edujinionline.com ----------------------------------------- Well to accurately repo this, you'll have to create a pair of Nant tasks.. one to get the Mutex and one to release it. The idea is that in your build file you get the lock, do some stuff, then release the lock. The AbandonedMutexException would show up just opening a couple of console windows and running the same test build (which had a sleep between getting and releasing the lock). HTH Andy > > Releasing the mutex woudl work find as it would use that static > > reference, but the other process still threw the exception. Oh well, [quoted text clipped - 11 lines] > http://eduzine.edujinionline.com > ----------------------------------------- Well to accurately repo this, you'll have to create a pair of Nant tasks.. one to get the Mutex and one to release it. The idea is that in your build file you get the lock, do some stuff, then release the lock. Oh, the tasks also took a lockName which was used to globally name the mutex. The AbandonedMutexException would show up just opening a couple of console windows and running the same test build (which had a sleep between getting and releasing the lock). HTH Andy > > Releasing the mutex woudl work find as it would use that static > > reference, but the other process still threw the exception. Oh well, [quoted text clipped - 11 lines] > http://eduzine.edujinionline.com > ----------------------------------------- > Well to accurately repo this, you'll have to create a pair of Nant > tasks.. one to get the Mutex and one to release it. The idea is that Hi Andy, Thanks for the input. SignatureHappy Hacking, Gaurav Vaish | www.mastergaurav.com www.edujinionline.com http://eduzine.edujinionline.com ----------------------------------------- Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
|
Reply to this Message
|
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.