merwa
ISP
- Dec 12, 2002
- 14
Hi,
What is SEMAPHORE ...what's it's role.Ur answer is appreciated
What is SEMAPHORE ...what's it's role.Ur answer is appreciated
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Semaphore
- Thread starter merwa
- Start date
- Status
jimbopalmer
Programmer
If you have many programs sharing the same data (databases are often written this way) you need some way to share infomation between running programs about which ones can have access to the shared data. the finer you allow them to share, the more semaphores you need them to be able to create.
Next disk block = 5
Program A reads 5
Program B reads 5
Prorram A uses block 6
Program B Uses Block 6
Program A adds one to Next Disk bock
Program B adds one to Next Disk bock
This is bad, you need semaphores to protect (latch) that memory area
I tried to remain child-like, all I acheived was childish.
Next disk block = 5
Program A reads 5
Program B reads 5
Prorram A uses block 6
Program B Uses Block 6
Program A adds one to Next Disk bock
Program B adds one to Next Disk bock
This is bad, you need semaphores to protect (latch) that memory area
I tried to remain child-like, all I acheived was childish.
- Status