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

Republican politics have been off-kilter for several years now because a large segment of the conservative base does not look back fondly on the Bush presidency.

Jonah Goldberg

I'm always fascinated by the dedicated monitors in a hospital. Non-standard cables, funny button shapes, odd LED colors, and lots of extra controls.

Brad Feld

Playwriting is the last great bastion of the individual writer. It's exciting precisely because it's where the money isn't. Money goes to safety, to consensus. It's not individualism.

John Patrick Shanley

Trying to break into the horror market seemed natural.

George Stephen

My career's had a lot of ups and downs. Once I started playing with John Peers in 2013, that gave me a huge lift, a lot of direction, which I needed.

Jamie Murray

There was a man who was an associate of jimmy Hoffa, who testified against Hoffa in his trial down in Tennessee. We had information from him that he and Hoffa did, in fact, discuss the planning of an assassination conspiracy against Bobby Kennedy.

Louis Stokes

My goal with our American Made program is to inspire people of all ages to become 'doers,' whether it's them learning how to make an easy weekday dinner or starting their own business.

Martha Stewart

If you try to hold on to something you don't have anymore, you can't be happy in the moment.

Jennifer Grey

I will spend anything on the best sheets in the world because I am going to be in them every night. I like them white and crazy soft.

Amy Landecker

I remember, one day, I just printed out about a hundred CVs, and I was running around London. I was going to modeling agencies, temping agencies, anything. I was so desperate.

Fleur East

U2 have a lot of religion, also people like Johnny Cash and Elvis. Those people weren't shy about it - it's nice there are people who've come before that were open about it.

Brandon Flowers

Don't keep your own schedule - that will eat too much of your time keeping your own schedule. And when you are tired, stop. Because if you are too tired, you become not productive, and you are wasting time.

Christine Quinn

If you don't like the people, you're just doing a sketch. Which, in most cases, is comedy minus some emotional backbone.

Christopher Guest

The greatest ability is dependability.

Bob Jones, Sr.

The greatest competitor was Bob Gibson. He worked so fast out there and he always had the hood up. He always wanted to close his own deal. He never talked to you because he was battling so hard. I sure as hell don't miss batting against him, but I miss him in the game.

Pete Rose

My career hadn't rocketed to the top of anything, but I've worked consistently and done things I've loved.

Max von Essen

But at any rate, the point is that God is what nobody admits to being, and everybody really is.

Alan Watts

I've had days when I go in my bedroom for 24 hours at a time. I call them my Cilla Black days, and they're literally black days. It's like the old Boomtown Rats song 'I Don't Like Mondays.' You just want to shut the whole day down.

Cilla Black

With roasting, you've really got to bring your A-game. I hate to admit it, but I probably think and obsess more about the roasts than my own series. Because there's so much attention focused on the roasts. It's like the 'Super Bowl' of comedy. Everybody is going to talk about it. Forever.

Jeff Ross

It was great being brought up in a Glasgow working-class tenement. It wasn't miserable, and it wasn't poverty stricken. It felt very safe, full of delights.

Peter Capaldi

I think it's very important to feed the body what it craves and not be in your head about it, panicking, carrying around some calorie-counting wheel in your bag or something equally absurd. I'm really not a fan of that at all.

Tracy Anderson

I totally commit and completely give myself to a relationship. Be warned, though - I don't like being taken for granted, so I can be pretty high-maintenance sometimes!

Priyanka Chopra

I believe in, and will to the best of my ability fight for, equal rights and freedom of opinion for everyone, regardless of colour, religion, nationality, orientation - you know the rest.

Binyavanga Wainaina

The United Nations has come under the control of outlaw nations and self-serving special interest groups.

Ginny B. Waite