pthread_cond_wait() simultaneously unlock the mutex (so that other threads can modify the linked list) and wait on the condition (so that pthread_cond_wait() will wake up when it is "signalled" by another thread). Now that the mutex is unlocked, other threads can access and modify the linked list, possibly adding items

Tony Nemo

Threads in C

pthreads library and threaded programming in C

#programming

#threads

#CS

Tony Nemo

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"dead list" that contains all stopped threads and then have a special cleanup thread that simply waits for an item to be added to the list. The cleanup thread calls pthread_join() to merge it with itself. Now your entire cleanup will be handled neatly and efficiently in a single thread.

Tony Nemo

mutexes are used to serialize access to *shared data*. Don't use them for non-shared data, and don't use them if your program's logic ensures that only one thread is accessing a particular data structure at a single time.

Tony Nemo

if you are using shared data, use mutexes for both reading and writing. Surround your read and write sections with pthread_mutex_lock() and pthread_mutex_unlock(), or use them any time a program's invariant is temporarily broken.

Tony Nemo

pthread_mutex_destroy() does not free the memory used to store the pthread_mutex_t. It's up to you to free() your own memory. Also remember that both pthread_mutex_init() and pthread_mutex_destroy() return zero on success.

Tony Nemo

pthread_mutex_lock() accepts a single pointer to a mutex to lock. If the mutex already happens to be locked, the caller will go to sleep. When the function returns, the caller will be woken up (obviously), and the caller will also now hold the lock. This call either returns zero on success.

Tony Nemo

You should always unlock a mutex that you've locked as soon as safely possible (to increase performance). And you should never unlock a mutex that you don't hold a lock for

Tony Nemo

When you call pthread_mutex_trylock() you'll attempt to lock the mutex. If the mutex is currently unlocked you'll get the lock, and this function will return zero. However, if the mutex is locked this call won't block. Rather, it will return a non-zero EBUSY error value.

Tony Nemo

pthread_cond_wait() call has not yet returned. Unlocking the mutex happens immediately, but waiting on the condition mycond is normally a blocking operation, meaning that our thread will go to sleep, consuming no CPU cycles until it is woken up.

Tony Nemo

This is exactly what we want to happen. Our thread is sleeping, waiting for a particular condition to become true, without performing any kind of busy polling that would waste CPU time. From our thread's perspective, it's simply waiting for the pthread_cond_wait() call to return.

Tony Nemo

Immediately after unlocking the mutex, thread 2 calls the function pthread_cond_broadcast(&mycond). By doing so, thread 2 will cause all threads waiting on the mycond condition variable to immediately wake up. This means that our first thread (which is in the middle of a pthread_cond_wait() call) will now wake up.

Tony Nemo

After thread 2 called pthread_cond_broadcast(&mymutex) you might think that thread 1's pthread_cond_wait() will immediately return. Not so! Instead, pthread_cond_wait() will perform one last operation: relock mymutex. Once pthread_cond_wait() has the lock, it will then return and allow thread 1 to continue execution.

Tony Nemo

I have too many ideas for a lifetime.

Taylor Wilson

Illness is a clumsy attempt to arrive at health we must come to natures aid with intellect.

Friedrich Nietzsche

I'm very physical. It's an important part of being a woman - feeling good about yourself and really being in tune with your personality.

Summer Glau

I couldn't do rap. I was trying. I don't know how. I'm not good enough to know.

Dee Dee Ramone

A lot of girls think they have to choose between being the smart geeky type or the beautiful bimbo.

Danica McKellar

Small businesses, you can give them capital, but what they often need as much is mentoring, advice and help with their business plan.

Karen Mills

Language cares.

Howard Nemerov

Who you are as a performer is one thing, but when you're making records, you're dealing with musicians' tastes, their goals, their wants, their needs, everyone's individual pride.

Scott Weiland

I've got about $30,000 in chips, not near enough.

Wilford Brimley

I'm pretty normal.

Jenna Bush

There was a whole display set up of all the X-Men paraphernalia. My wife couldn't resist telling this 5-year-old boy that I was Wolverine. The little kid looked up at me and he was staring at me.

Hugh Jackman

I've always deplored bad heterosexual values that dictate the minute a marriage is over the former partners no longer speak to each other; only straights could be so cruel and inhuman as to reject totally the person with whom they've shared their life for 20 or 30 years.

Edmund White

We fail to realize that mastery is not about perfection. It’s about a process, a journey. The master is the one who stays on the path day after day, year after year. The master is the one who is willing to try, and fail, and try again, for as long as he or she lives.

George Leonard

All the stories I write come from someone I've met or some anecdote I've heard.

Edith Pearlman

I think personal growth has much to do with acting ability.

Beverly D'Angelo

I am an unconventional beauty. I grew up in a high school where if you didn't have a nose job and money and if you weren't thin, you weren't cool, popular, beautiful. I was always told that I wasn't pretty enough to be on television.

Lea Michele

'Ludacris' is something that I made up. It just kind of describes me. Sometimes I have like a split personality. Sometimes I'm cool, calm, and collected, and other times I'm beyond crazy.

Ludacris

Many openly show discontentment with their looks, but few with their intelligence. I, however, assure you there are many more plain minds than faces.

Bryant H. McGill

Gosh, all a kid has to do these days is spit straight and he gets forty-thousand dollars to sign.

Cy Young

On the small scale, 'Ico,' I think, actually delivered a small new thing: holding a character's hand and really feeling like your job is to rescue this person, and establishing a personal connection.

Warren Spector

When you think about flying its nuts really. Here you are at about 40000 feet screaming along at 700 miles an hour and youre sitting there drinking Diet Pepsi and eating peanuts. It just doesnt make any sense.

David Letterman

I read a funny story about how the Republicans freed the slaves. The Republicans are the ones who created slavery by law in the 1600's. Abraham Lincoln freed the slaves and he was not a Republican.

Marion Berry

People do not change, they are merely revealed.

Anne Enright

Take your victories, whatever they may be, cherish them, use them, but don't settle for them.

Mia Hamm