I wrote this answer down because I thought this would be a fun (and fitting) analogy: Think of a lockable object as a blackboard (lockable) in a class room containing a teacher (writer) and many students (readers). While a teacher is writing something (exclusive lock) on the board: Nobody can read it, because it’s still … Read more
Notepad reads files by first mapping them into memory, rather than using the “usual” file reading mechanisms presumably used by the other editors you tried. This method allows reading of files even if they have an exclusive range-based locks. You can achieve the same in C# with something along the lines of: using (var f … Read more
Just in case someone looking for a solution to this for a Windows based system or NAS: There is a built-in function in Windows that shows you what files on the local computer are open/locked by remote computer (which has the file open through a file share): Select “Manage Computer” (Open “Computer Management”) click “Shared … Read more
The following code should do the job, it is cross-platform and runs on Python 2.4-3.2. I tested it on Windows, OS X and Linux. from tendo import singleton me = singleton.SingleInstance() # will sys.exit(-1) if other instance is running The latest code version is available singleton.py. Please file bugs here. You can install tend using … Read more
Found an article titled “MYSQL WITH NOLOCK” https://web.archive.org/web/20100814144042/http://sqldba.org/articles/22-mysql-with-nolock.aspx in MS SQL Server you would do the following: SELECT * FROM TABLE_NAME WITH (nolock) and the MYSQL equivalent is SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED ; SELECT * FROM TABLE_NAME ; SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ ; EDIT Michael Mior suggested the following … Read more
Great question. I maybe wrong.. Let me try.. Revision#2 of my orig answer.. with a little bit of more understanding. Thanks for making me read 🙂 lock(obj) is a CLR construct that for (intra-object?) thread synchronization. Ensures that only one thread can take ownership of the object’s lock & enter the locked block of code. … Read more
In my case, the disk ran out of space, so I had to delete files from the hard drive to make space.
A lock occurs when multiple processes try to access the same resource at the same time. One process loses out and must wait for the other to finish. A deadlock occurs when the waiting process is still holding on to another resource that the first needs before it can finish. So, an example: Resource A … Read more
I have the choice in between either having a bunch of mutexes or a single one for an object. If you have many threads and the access to the object happens often, then multiple locks would increase parallelism. At the cost of maintainability, since more locking means more debugging of the locking. How efficient is … Read more
The difference between a recursive and non-recursive mutex has to do with ownership. In the case of a recursive mutex, the kernel has to keep track of the thread who actually obtained the mutex the first time around so that it can detect the difference between recursion vs. a different thread that should block instead. … Read more