I just learned about threads about 4 days ago. You can’t believe how much better a 13+ min video is than my 1 hour lecture in explaining threads.
@PortfolioCourses Жыл бұрын
That's awesome feedback thank you, I'm glad you enjoyed the video Leo! :-)
@waynec369 Жыл бұрын
Yes... yes I can...
@happygofishing Жыл бұрын
university lectures are always overenginneered.
@wizardatmath7 ай бұрын
I believe it.
@pranitp.293 ай бұрын
@@happygofishingunderengineered too as one might say.
@dianafarhat9479 Жыл бұрын
There are very few tutorials on this topic. Thank you for your work!
@PortfolioCourses Жыл бұрын
You're welcome Diana! 🙂
@safarmaihoon4585 Жыл бұрын
You know what!! This is better than hours of lectures. So crisp and to the damn point! 👏👏👏👏 Now I can start reading other references. Thanks for the video.
@PortfolioCourses Жыл бұрын
You're welcome Safar, I'm glad you enjoyed the video! :-)
@ButteryCowEgg2 жыл бұрын
Just wanted to say that I found your channel today and you have done some amazing work on your channel
@PortfolioCourses2 жыл бұрын
Thank you very much Jack! I'm glad you enjoy the content. :-D
@hengyili46624 ай бұрын
You are better than my professor in terms of explaining things. Thank you !!!
@mansbjork57218 ай бұрын
We're studying this at university right now and I have to say this is very much useful. It's almost clear after the first watch only.
@atchau64663 ай бұрын
13mins video is more valuable than 2 hours lecture on my university :D
@genetechagency2 жыл бұрын
They way you explains with examples...Marvelous sir
@PortfolioCourses2 жыл бұрын
Thanks for the kind words Junaid! I'm glad you enjoyed the video. 🙂
@p_molnar2 жыл бұрын
best ASCII presentation I've seen so far.
@PortfolioCourses2 жыл бұрын
Thank you Peter! :-)
@emmadhamid6578 Жыл бұрын
Defined greatly n precisely ✨ best single shortest video to learn whole fkn threads topic …
@PortfolioCourses Жыл бұрын
Thank you very much for the kind positive feedback Emmad! I'm glad you enjoyed the video. :-)
@user-cp3tm2nx5l7 ай бұрын
You Sir are an angel, I've been stuck trying to understand how to use threads in C for SOOOO LONG and this tutorial makes so much sense, i was actually able to code along and it works and i get it ! AAAAH I'm so relieved, it finally makes sense, THANK YOU SO MUCH !
@alvarobarboza5730 Жыл бұрын
something that I particularly liked is .. the comparison you do at the end, this shows how useful multi-threading is
@theyayaa7 ай бұрын
I am listing this channel as a reference in my school project because I have learned a ton of c from here. Thank you!
@RahulYadav-df9sp6 күн бұрын
Best video ever !! on threads topic
@M3t4lik Жыл бұрын
I've been playing around with OpenMP in VS and it works great for optimizing loops for parallel execution, where the threads seem to execute in random order each time the program is run. However, after looking at the documentation a little more attentively, there are a number of command parameters associated with the pragmas that would make life easier rather than trying to play around delay loops, ordering and placements. Great intro to threading.
@PortfolioCourses Жыл бұрын
Cool, thanks for sharing that, I'm glad you enjoyed it! :-) I think I'm due to cover threading some more but there are so many topics I want to cover haha...
@AibekDandaev2 жыл бұрын
wanted to say that you've done some amazing work on your channel
@PortfolioCourses2 жыл бұрын
Thank you very much! 😀
@HuntingKingYT10 ай бұрын
You can also get the return value, you just have to pass a pointer to the place where the return value of the function will be put at (the result is also statically a void pointer!) as the second parameter to pthread_join(): void* add(void* param) { long* result = (long*)malloc(sizeof(long)); *result = *(long*)param + 1; return result; } int main() { pthread_t thread1; long value = 10; pthread_create(&thread1, NULL, &add, &value); long* result; pthread_join(thread1, (void**)&result); // output pointer to a `long` pointer! printf("result: %ld ", *result); // 11 free(result); return 0; }
@lucasf.v.n.41978 сағат бұрын
very well explained sir;
@heitorheitorheitor81582 жыл бұрын
you teach so well man, great job! :p
@PortfolioCourses2 жыл бұрын
Thank you! :-)
@OdinRu1es6 ай бұрын
Multithreading it’s not about executing multiple instructions at the same time. It’s about sharing resource beetween them.
@adityak7877 Жыл бұрын
I think i have clear understanding about pthreads post watching this video....thanks for the free tuts.
@PortfolioCourses Жыл бұрын
You're welcome Aditya, I'm glad the video was helpful for you! :-)
@juliannafotheringham7101 Жыл бұрын
great video, so clear!
@PortfolioCourses Жыл бұрын
I'm glad you enjoyed it Julianna! :-)
@gabrielepasqualini45673 ай бұрын
great example, very usefull ty
@raffayylsamuill91645 ай бұрын
Really thank you for this great explanation
@pietrocallandrone6012 Жыл бұрын
This video is a gem, thanks man!
@PortfolioCourses Жыл бұрын
You’re welcome Pietro, I’m glad you enjoyed it! :-)
@fridaaa08 ай бұрын
Thank you, super digestible!
@paulalucena217011 ай бұрын
great explanation! Thanks
@lowground9345 Жыл бұрын
man i love you thanks so much for this vid helped A LOT
@PortfolioCourses Жыл бұрын
You're very welcome, I'm so glad to hear the video helped you out! :-)
@depsylon4235 Жыл бұрын
great and easy to follow explanation
@PortfolioCourses Жыл бұрын
Awesome, I'm glad you enjoyed it! :-)
@therealajmelmuadz4 ай бұрын
Amazing video mate
@PortfolioCourses4 ай бұрын
I’m glad you liked it! :-)
@baruchben-david4196 Жыл бұрын
For some of us, we also have to add a flag to the linker: -lpthread.
@pral42066 ай бұрын
Did you make a video about semaphores also? My teacher is covering that right now and it might be helpful if there was a video about that also.
@anthony68419 ай бұрын
Very helpful, thank you
@djoykeabyah59049 ай бұрын
thank you for the explanation I was only wondering why my single thread execution is faster in the example?
@MSDelhi2 Жыл бұрын
nice explanation with easy example🙂
@PortfolioCourses Жыл бұрын
I’m glad you enjoyed it Manish! :-)
@audunoklevik4435 Жыл бұрын
Good introduction! Thanks :)
@PortfolioCourses Жыл бұрын
You're welcome Audun! :-)
@st1ers1 Жыл бұрын
Very well explained!
@PortfolioCourses Жыл бұрын
I'm glad you enjoyed it! :-)
@alvarobarboza5730 Жыл бұрын
Hi. Just watched this video. Very very cool and interesting. I started learning C due to my interest in numerical methods. In the video you mention that certain hardware and software specs must be met, in order to run threads in C? can you elaborate on this please? it seems a regular PC won't be able to run multi-threads thank you !!
@abanoub70028 ай бұрын
A regular PC would most likely be able to run multiple threads, as the 'pthread_t' type doesn't reference the actual CPU thread directly, but instead references OS threads, which are created on demand by the OS itself depending on things such as available execution resources such as RAM and CPU among other things. Most modern OS's can make up to tens of thousands of threads (depending on the hardware itself of course, on average hardware you would be having around 12), so not meeting hardware requirements shouldn't be a problem. But yeah, as long as the amount of OS threads created is less than or equal to the amount of physical threads you have, you should be able to run anything you want in parallel.
@tecoberg5 ай бұрын
It is not clear to me why when pthread_join commands were together the program didn't stop in the first one until the computarion is finished and after that it went to the second pthread_join like shown if you put them immediately after the pthread_creates
@pareus725110 ай бұрын
Sir I respect you so much
@PortfolioCourses9 ай бұрын
Thank you for leaving this kind feedback! :-)
@vinushan2411 ай бұрын
Thank you man.
@user-xn3ym4cr6h Жыл бұрын
in fact , its gonna take more time compared to the single threaded version , create pthread is big overhead for this single program , user time and sys time has actually increased
@PortfolioCourses Жыл бұрын
The way user and sys time works in multithreaded programs isn't straightforward: stackoverflow.com/a/556411. In particular: "On a multi-processor machine, a multi-threaded process or a process forking children could have an elapsed time smaller than the total CPU time - as different threads or processes may run in parallel. ". So yes user time can go up, but the elapsed time can go down.
@berktopbas14962 жыл бұрын
Hello, great tutorial! I just wanted to ask that as you explained difference between the concepts of concurrent and parallel execution at the beginning in the video, i suppose, to that explanation, at 12:12, you should have said that "running parallel" instead of "running concurrently". In my opninon, if they were to run concurrently, it could even take more than 4.5-5sec(run-time for single thread) because of context switch. Of course, i assume that your machine has multiple CPUs and multithreading-supporting software, as most modern PCs have today.
@PortfolioCourses2 жыл бұрын
No, the description is accurate as it is, I said that they were running concurrently and added it looks like they were running in parallel too (i.e. due to the execution time): "We can see that the multithreaded program is running roughly twice as fast as the single threaded program, and that makes sense because we have two threads now running concurrently, and in this case it looks like they're running in parallel as well". All threads run concurrently, and in this case, on my machine, they are also running in parallel based on the execution time. Parallelism implies concurrency, it's a "subset" of concurrency, but concurrency does not imply parallelism. Maybe I'll make a video on concurrency vs parallelism though, it's an interesting topic. Concurrency won't help in a situation like this with a computation occurring in each threads, it could even be worse due to the context switch that you mention. But it can improve performance drastically if the threads are working on I/O bound operations for example, which is something I think a lot of people don't realize.
@friendsclub4887 Жыл бұрын
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@bharadwajm7950 Жыл бұрын
Why are you passing address as argument while calling function in pthread_create ? Why can't you directly pass the value ? Why (void*) & value1 ? Why not (void*) value1 ? Near 7:17
@PortfolioCourses Жыл бұрын
Good question Bharadwaj! Ultimately, we do that because it's the way that the pthread library was created. :-) One thing to keep in mind is that we don't call the function in pthread_create. What we're doing is calling pthread_create, and we give it as arguments the function to call, and a pointer to the value we want to use as an argument. pthread_create() will at some point later "call our function in a new thread", and at that time the function is supplied with that pointer value as an argument. Because the pointer is a void pointer, we can use it to essentially "pass anything we want" to the function.... e.g. a pointer to something like a struct or array that contains all the data needed by the function. Hopefully this helps! :-)
@fathimamiznathajuddeen9175 Жыл бұрын
Thank you sir
@PortfolioCourses Жыл бұрын
You're welcome! :-)
@nabanitabanerjee6570 Жыл бұрын
Very useful.
@PortfolioCourses Жыл бұрын
I’m really glad you found it useful Nabanita! :-)
@tracetv8115 Жыл бұрын
I am a little bit confused now. Ur example runs concurrently and not parallel right? If yes, how I have to code that it runs parallel then or the os decides what to do and I can not control that? Great video anyways!
@PortfolioCourses Жыл бұрын
Yes it runs concurrently but not in parallel. To get parallel execution you would use another solution, for example: curc.readthedocs.io/en/latest/programming/OpenMP-C.html. :-)
@lawniczakjohn Жыл бұрын
Another awesome video! I'm getting into threads now. Is multi-threading much different in C++? I'm sure they are very similar...
@PortfolioCourses Жыл бұрын
I'm glad you enjoyed it John! :-) So prior to C++11 we just used the pthreads library in C++, but now there is the thread library we can use instead: www.geeksforgeeks.org/multithreading-in-cpp/.
@lawniczakjohn Жыл бұрын
@@PortfolioCourses That's great info thanks!
@PortfolioCourses Жыл бұрын
@@lawniczakjohn you're welcome! 🙂
@bofa-zi4fj Жыл бұрын
What are the main differences between threads and the fork() system call? And why would you choose one over the other?
@PortfolioCourses Жыл бұрын
This is a really good question. :-) It's a big topic though, I definitely want to do a video on exactly this topic one day. For now though I can just point to some resources online such as these ones to explain things: stackoverflow.com/a/8514943 stackoverflow.com/questions/11662781/when-is-clone-and-fork-better-than-pthreads
@zoquevil4792 Жыл бұрын
Hi ! I just started this subject when I was reading about the "Dining philosophers problem" and how to avoid the deadlock , starvation in this case .... you'll learn about mutex, semaphore/signal , the synchronization process, a huge among of information to learn...the call system fonctions are very tricky when you think about them and at the same time it's a very exiting subject to be familiar with because it's full of suspense!!! .. Thanks Kevin and as always your videos are very amazing!!! @@PortfolioCourses
@mastermax777710 ай бұрын
why dont you show how to get a return value from the thread function?
@PortfolioCourses10 ай бұрын
I think I may make more videos covering more aspects of pthreads as these videos have become popular. :-)
@spurthidantu6890 Жыл бұрын
How do i prevent memory leaks in Pthreads? The first time i execute the program, answer is right but if i add a while loop, it is providing incorrect values.Even after adding pthread_join, same thing is happening.
@PortfolioCourses Жыл бұрын
If we dynamically allocate memory using a pthread, either as part of creating the thread or in the function called by the thread, we need to use free() to free the dynamically allocated memory the same as usual. 🙂 In this example, we don't use any dynamically allocated memory. A while loop could produce incorrect results for a number of reasons, such as variables being re-used, etc.
@ShopperPlug2 жыл бұрын
12:15 - I wonder how is it possible for the program to run faster when it is executing code concurrently with only one core, the physics behind it doesn't make sense... Does code do indeed run faster simply due to concurrency with one core?
@PortfolioCourses2 жыл бұрын
The code in the video is running in parallel in addition to running concurrently, that’s why it’s faster. :-)
@thomaslindell54486 ай бұрын
Hahn great material but I’m blind. How bout dark mode
@moadelhaddad4376 Жыл бұрын
Hello , Thanks for the video. It is possible to pass 2 arguments to a thread?
@PortfolioCourses Жыл бұрын
Great question Moad! :-) We can if we use a struct as a way to pass both arguments: www.cse.cuhk.edu.hk/~ericlo/teaching/os/lab/9-PThread/Pass.html.
@moadelhaddad4376 Жыл бұрын
@@PortfolioCourses thanks for answering :)
@liathecat775727 күн бұрын
Bro pls use dark theme
@undeadpresident Жыл бұрын
Anyone know how to use a C file that uses pthreads to work with Python's ctypes library? Anything that has the line "pthread_create" Python says it can't find it. Something to do with dependency...I don't get it.
@PortfolioCourses Жыл бұрын
Unfortunately I don't have a video on this topic. Hopefully someone else is able to help you out. Eventually I'd love to cover ctypes in Python. Sometimes putting the error message into Google along with the text "stackoverflow" or "reddit" can lead to helpful conversations online that help to resolve the issue.
@undeadpresident Жыл бұрын
@@PortfolioCourses that was a good idea to go to stack overflow, they pointed me in the right direction and I got it solved. I had to specify a path in Python to the dependencies in mingw. First time I had to do that, I had thought I was doing something wrong with gcc. I've used ctypes a fair bit as a way to speed up my python code and learn C at the same time. I've just passed arrays to it but haven't got into any of the more hairy stuff like making python objects into ctypes structs or w/e though. On stack overflow I came across a library I hadn't heard of called omp which does multiprocessing in C also. I've only been programming less than a year so I'd be interested in hearing from more experienced people the pros/cons between pthreads and omp.
@PortfolioCourses Жыл бұрын
@@undeadpresident I'm glad you got that figured out. 🙂 Maybe someone else viewing the video can address your other question.
@undeadpresident Жыл бұрын
@@PortfolioCourses I was playing with omp a little bit and it looks like instead of passing arguments in, you use the thread ID to differentiate what the threads do, and that in pthreads the ID just continues to count up and up each time you loop through the code that splits the program, but in omp it restarts the count each time. Not trying to talk you to death, just thought it might be interesting if you haven't messed with it.
@PortfolioCourses Жыл бұрын
@@undeadpresident Cool, thanks for sharing, I want to play around with more myself next month sometime.
@subtainmushtaq32372 жыл бұрын
What if we have to pass multiple parameters in a function?
@PortfolioCourses2 жыл бұрын
That's a great question Subtain, I think I'm going to make a video on exactly this question. :-) We can use a struct to pass multiple parameters by using multiple members of the struct, like this example: www.cse.cuhk.edu.hk/~ericlo/teaching/os/lab/9-PThread/Pass.html.
@subtainmushtaq32372 жыл бұрын
@@PortfolioCourses thank you sir !
@PortfolioCourses2 жыл бұрын
@@subtainmushtaq3237 You're welcome! :-D
@FatimazahraeBazaz3 ай бұрын
please use dark mode !!! my eyes screaming haha
@jayantvarma7052 Жыл бұрын
there are so many ads in a 13 min video :(
@PortfolioCourses Жыл бұрын
Thank you for the feedback!
@Awwe12675 Жыл бұрын
I hate it 😂 I need focus in library to understand how it implemented
@PortfolioCourses Жыл бұрын
Oh you need to know how to implement pthreads, from scratch? I don't know how to do that sorry, that's getting into some lower level programming that I don't really know enough about to talk about off the top of my head. :-)
@Awwe12675 Жыл бұрын
@@PortfolioCourses yeah I believe it is system call so I downloaded the gun c library reference manual to figure out
@PortfolioCourses Жыл бұрын
Good luck! :-)
@aaronderby25819 ай бұрын
Is it necessary to always "join the threads" or is it just for when you need to be sure a thread has finished before moving on? For instance, if i want s thread to continuously run until the program dies, would I ever really need to join it?
@NarongTantayanon4 ай бұрын
why my result turn to be single thread is faster than multi thread? running in WSL ubuntu ❯ gcc -o s main.c ❯ time ./s Add: 1 Add: 2 Add: 3 Add: 4 Add: 5 Add: 6 ./s 55.02s user 0.01s system 99% cpu 55.032 total ❯ gcc -o m main.c ❯ time ./m Add: 5 Add: 4 Add: 3 Add: 6 Add: 2 Add: 1 ./m 68.42s user 0.01s system 596% cpu 11.464 total