Programming :: Deadlock Due To Crash Inside Critical Section?
May 12, 2011
The following two pieces of codes share printing to stdout with a POSIX semaphore /dev/shm/sem.abcd
sema1.c:
Code:
int j;
sem_t *sem = sem_open( "/abcd", O_CREAT, S_IRUSR|S_IWUSR, 1 );
j = 0;
while (j < 100) {
[Code].....
If started at the same time, the first will finish in about 10 seconds; the second 20 secs.
What I want to ask is, if the first program crashes at Checkpoint A, then B will never gets to continue, then normally how do programmers avoid this kind of deadlock due to crashes inside the critical section?
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Nov 19, 2010
I have this project for my operating systems class and I have put together the basic flow chart to aid me in writing the program. I know how to use pipes as a buffer to hold info. I know how to create a binary semaphore. But what I dont know is this:
How to "use a delay adjustment parameter K in the critical section to adjust the speed of the display process to show that without semaphore protection the displayed contents of the buffer are randomly interleaved."
First off, I am definitely not asking anyone to give me the solution. But I do need some guidance. So I figure there will be an if statement with two options:
1. If true, use semaphore protection to enter/exit critical section
2. If false, no semaphore protection -- this is where the contents of the buffer should be interleaved.
Now does that mean that as each child process enters the non-protected critical section, it should "sleep" for a randomized time? I mean, will this allow my output to be interleaved?
So lets say my command line looks like this:
what happens to the 100? Is it randomized using rand and srand and passed as a parameter to sleep() inside the critcal section?
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Quote:
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Quote:
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