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Why and how to use condition variables? - Pthreads

Posted 02-06-2013 at 01:40 AM by Aquarius_Girl
Updated 02-06-2013 at 05:55 AM by Aquarius_Girl

Q: What is a condition variable?
A: A condition variable is a variable of type `pthread_cond_t`. It is
used to suspend the thread execution until some condition is true.

Q: Is a condition variable dependent on a mutex lock to work properly? Why?
A: Explaining with an example:

Assumptions:
1. There is a variable `x` whose current value is 0.
2. There is a thread `threadA` whose task is to start some job once the
  variable `x` reaches the value 1000.
3. There

...

Aquarius_Girl

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Why and how to use `pthread_join()`? - PThreads

Posted 05-23-2012 at 01:00 AM by Aquarius_Girl
Updated 08-24-2012 at 01:50 AM by Aquarius_Girl

Q: What is join with respect to Pthreads?
A: Join is a functionality of Pthread library which allows the originating thread to wait for the completion of all its spawned thread's tasks.

Without join the originating thread would exit as soon as it completes its chores, completely ignoring the states of its spawned threads. Due to this, even if any of the spawned threads is in middle of its chore, it'll simply get aborted.
Problem statement:
In the below code I have

...

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Why and how to use Mutex locks - Pthreads

Posted 02-27-2012 at 11:06 AM by Aquarius_Girl
Updated 05-21-2012 at 01:51 AM by Aquarius_Girl

Problem:
Underlying operating system may schedule the threads on the basis of some algorithm which works on time limit (threads may be allowed to run only for certain durations of time, thus preventing the other threads from starvation), priority (higher priority threads may interrupt the lower priority threads during their execution), or some other factor.

These factors may cause a thread to sleep before it completes its task fully. Another thread may get scheduled meanwhile...

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