It is used by the process that is writing in the file and it ensures that no other process should enter the critical section at that instant of time. Semaphore "writer": This semaphore is used to achieve the mutual exclusion property.The following semaphore variables will be used in our solution: So, we will use the above two concepts and solve the reader-writer problem with the help of semaphore variables. But if a process is reading a file and another process is demanding for the write operation, then it should not be allowed. If a process is performing some read operation only, then another process that is demanding for reading operation should be allowed to read the file and get into the critical section because the read operation doesn't change anything in the file.no other process should be allowed to enter into the critical section(learn more about critical section from here). If a process is performing some write operation, then no other process should be allowed to perform the read or the write operation i.e.We can solve the above two problems by using the semaphore variable(learn more about semaphore from here). Another problem is that if a process is reading the file and another process is writing on the same file at the same time, then this may lead to dirty-read because the process writing on the file will change the value of the file, but the process reading that file will read the old value present in the file.Only one process should be allowed to change the value of the data present in the file at a particular instant of time.
All these processes can perform these two operations. Basically, we perform two operations on a file i.e. In an Operating System, we deal with various processes and these processes may use files that are present in the system. Now, you are done with the prerequisites of the blog, so let's get started with the reader-writer problem. If you have no idea about the process synchronization, then learn from here. In this blog, we will learn about the Reader-Writer problem in Operating System which is used for process synchronization. Also sorry for writting a book.In the last blog, we learned about the Producer-Consumer problem in Operating System. I have googled everywhere and can't find out.Īny help with this will be much appreciated. Does anyone know if Vivitar uses a proprietary SD card or something stupid like that. I have emailed tech support at both Vivitar and and ATP to ask for their advice but no luck yet. The camera will also recognize that the card is locked if I flick the switch on the side of the card.
I have even downloaded software for the web to wipe out the SD card. I'm thinking that there is no way that two cameras and two memory sticks are defective. I then went to FutureShop and bought a higher end ATP 512Mb card that is guaranteed 100% compatible with all cameras. Neither camera could read it then either, even after trying to reformat it in the camera. I then poped the card into the card reader on the computer and tries formating it as FAT 16 bit. 256Mb, Went I brought it home I put it in the camera and it asked me to format the card, I then tried on both cameras and neither camera could format the card. I have previous experience with some of the higher end Sony Digital SLR cameras so I went off to the store, Wal-Mart, and picked up the cheapest SD card that I could find.
The only problem is that it only has an internal 8Mb memory however the manual says that it is expandable with an SD card. I know about Vivitar's reputation but it was a gift and it does take decent pictures of out kids. Well me and my wife each got a Vivicam 3603z digital camera for Christmas. Okay, so first off, I havn't slept for a couple of days trying to figure out this problem.