Difference between processes and threads

Source code can be found here:
code-vault.net/lesson/18ec194...
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[@thomasl863]

I love this style of teaching. It's like investigating the functionality of the code instead of having it lectured about conceptually

[@kevinzebb]

pls never stop making vids man, maybe at times it may seem boring or stressful, but you're helping out so much. BITTE!

[@CodeVault]

Thanks for the encouragement! I promise I'll make new videos in the future

[@codex8797]

Bro you are basically my Operating Systems teacher now. You cover all the topics I have seen in class but in a clearer way. Also your videos have helped me with a lot of previous programming classes I took. Thanks so much man, greetings from Brazil.

[@nsabesz]

videos with 200k+ views teach nothing compared to this, you are the best

[@matthieu9303]

Very interesting, very clear. Straight to the essential. That's how every tutorial should be. Thanks.

[@ismailcetin3253]

Hey CodeVault. I came across your lectures in searching for a good resource on Operating Systems and found them very useful. Your explanations are pretty clear and detailed. Thank you and keep up the good work.

[@marianaaa24]

This was such a cool video, I finished your Processes video list and now getting through this one :) Thank you!!

[@ivanphoenix8064]

This is just worth every single second, ty man, quality content every single time! You just got a subscriber.

[@teodoravlad3023]

I wouldn't have passed my processes exam without you and now I have a threads exam. Thank you!

[@silviudinca6501]

You are explaining so well man. Im understand so good this concepts.

[@stephenjames5745]

This was an excellent explanation. Thank you!

[@RushikeshDhekare1989]

You are so damn underrated. Tomorrow I have an OS lab exam. Hugee help. Thanks and keep up the good work.

[@user-ji3mn7og7q]

Thank you soooo much! Always enjoy the lab session after the lecture and this video explains the concept so well in practice!

[@adi11cr7]

Really comfortable with the way you teach. Please do a video on dining philsopher problem

[@marcophono3434]

Thank you so much for your teaching! i learned a lot watching them!!

[@gian6725]

The best explaination i found so far

[@AloneInTheSummer]

What a guy! Thank you for these videos.

[@seymanurkaraoglan9888]

made it easy to explain this subject in practice thanks from Turkey ❤❤

[@turki8542]

you are the best!literally

[@bsgamer5069]

❤️your explanation is awesome

[@duanakshbandi6494]

Amazing as always

[@sony1979iq]

i hoped that i saw your series before i took the exam :(, very nice explanation thumbs up

[@user-fb4ln3js5n]

thank you very much from Moscow, school21 student! You're the best

[@ojussinghal2501]

The most underrated channel on youtube

[@navidnouri151]

Thank you!

[@dmbdwn]

this channel is proof not all heroes wear capes.

[@fernandaeschallots2485]

thx! You're the best

[@kk3528]

Very good 🙏👌

[@AMSHASH-xw7lt]

Simply Amazing !!!!! What text editor did you use that allow you to split your screen into three sections ?

[@CodeVault]

Visual Studio Code

[@yazou4564]

best vdieo ever!

[@dimadem]

thank you so much

[@antarbasu5342]

Great Video. I am joining discord today

[@dijkstra4678]

This is great

[@meleearcher7684]

Thanks for the tutorial about pthread and it helps me a lot; I have a question with regards to sleep() when you are showing that threads are sharing memory; what does it do to the threads? If the sleep function is not added, it does not seem to be showing the results as the one with it. why does it happen like that? Thanks.

[@CodeVault]

Ahh, I just wanted for the second thread to wait until that x++ in the other thread is executed. There are better ways, of course, but I don't want to overcomplicate things right in the beginning

[@meleearcher7684]

@@CodeVault Got it. Thanks so much for your answer. Please continue making tutorials about C. You are great !

[@mittyouness9163]

I have a question: so how useful threads are, or what's the benefits of using threads and not just calling a function(its seem more faster than creating threads)?, and thank u for your BiiiG effort doing us like those videos

[@CodeVault]

It's to take advantage of all of your computer's processes. Nowadays you hear a lot of computers with CPUs of 4, 8 or even 16 cores. Well, each core can basically run a thread at a time. Say, you have a 4 core CPU: If you only use the main thread for your program at *most* you can use 1 core of that CPU (that's 25% of your total processing power). With 4 threads you could use all 100% of it

[@vincegelo4495]

I have a question, what’s the difference between a usual function call and a thread call, where both calls follow the same code implementation. Moreover, is a function call faster than thread call? Given that in the process only one thread is created.

[@CodeVault]

There's a bit of an overhead when creating a thread... so usually you want to create a set of threads at the beginning of the process and use them until the process finishes execution. For sure simply calling a function is going to be faster

[@Codality]

THE BEST

[@suhass5979]

I have a doubt, so tell me what I have understood is correct or not 1. In processes only one can execute at a time, so even when we use fork system call the parent or child either one of them can execute at a particular point of time/stay in the running state and they do context switching to achieve multiprogramming 2. But in the case of threads they can execute simultaneously and use the multithreaded CPU cores Is this correct sir??

[@CodeVault]

No. Both can execute simultaneously

[@DINO5551000]

When you said the other thread sees the changes to x, I immediately had to think about, what if the thread running the incrementing didn't finish first, but rather the second thread finishes, the one that just sleeps and prints the value of x, the value of x wouldn't have been incremented yet due to the first thread not having finished yet? I suppose pthread_join makes sure that the threads run in order by waiting on the first thread and then the second with join so the question I thought about is irrelevant, right?

[@CodeVault]

It's not at all irrelevant. You're asking the right question. Multi-threaded programming could become unpredictable based on the order of execution of the threads themselves. As programmers we don't want that, it would be chaos. In this playlist we actually take a look at tools that make multi-threaded programs predictable again (mutexes, barriers, semaphores etc.). And teaching you how to make such programs predictable is one of the goals of these videos

[@Sdirimohamedsalah]

Operating system runs processes and identify them by an ID each process can contain a set of instructions.. eg threads, functions …

[@yasminamran5]

Ypur vedios are great. Would you fo one about processe I anffinity?

[@CodeVault]

I'll look into it

[@somnath2536]

one question..you have taken x as global data to threads and in case of process it is local to main. how things works if thread is having local variable(X).

[@CodeVault]

That would be local to every thread, and thus each thread would be modifying its own x variable

[@ivanmoren3643]

Right, and if x had the storage class _Thread_local (c11) it wouldn't change in the threads example either?

[@CodeVault]

Yea, exactly

[@matyasmarkkovacs8336]

Good tutorial, but I have a few questions. When to use which one? Do threads and processes have anything to do with my CPU cores and CPU threads? How many threads and processes can I create on a 4 core CPU?

[@CodeVault]

The operating systems have been coded in such a way that threads and processes are an abstraction and you have to care about the underlying hardware. The limit of how many threads and processes is determined by the operating system as well. From here you can Google the exact numbers and more details about them. For example here are the limits for Windows: techcommunity.microsoft.com/t5/windows-blog-archive/pushing-the-limits-of-windows-processes-and-threads/ba-p/723824

[@matyasmarkkovacs8336]

@@CodeVault Thank you for the information!

[@booksvip8273]

Bro you're amazing keep going and don't stop making new vids

[@georgechacko4793]

How can we conclude on a decision regarding the usage of fork() or threads during design.. what all criteria we need to consider as part of choosing fork() or threads

[@CodeVault]

I guess it mostly depends on how independent you want your processes/threads to be. If a process crashes and you want everything else to still work, you'd have to use processes, for example. Other considerations are memory usage (each process has its own memory while threads can easily share the same memory space), bandwidth... usually, with processes you want a message-based data sharing mechanism (like with pipes) and concurrency if those processes/threads are distributed, how many things doyou need synchronized? It's much more difficult to synchronize processes than it is threads.

[@georgechacko4793]

@@CodeVault thanks a lot for your support

[@stefansilverio245]

how do you get to work with mingw?

[@stefansilverio245]

did you port the header file over somehow? or are you using cygwin? or is this on linux?

[@CodeVault]

It's on Linux. I have a video on how I'm actually running my code here: code-vault.net/lesson/tv93s6yw9r:1610568955955

[@brightlyricsmusic]

sir please upload more videos pleaseeeeee

[@abhaygaikwad6251]

understood

[@persia5195]

Can I run this program on windows?

[@anushkapopalghat3941]

The sys/wait header file is not working on my IDE. It shows the error "cannot open source file "sys/wait.h"C/C++(1696)". Can anyone help me with this? I've tried downloading the library from linux, but that's not working either.

[@CodeVault]

What I'm showing here only works on Linux (and MacOS). You will need to install something like WSL for Windows

[@ZebedeusZwalper]

Superb series ! However, I have a question:At time 4min25 you show that these threads have the same PID numbers But if I run htop in Linux, I see a different unique number for each thread? Any ideas?

[@CodeVault]

Threads are treated as processes in Linux. It's quite technical and I don't want to explain things wrongly but you can research more on the manual files of pthread: man7.org/linux/man-pages/man7/pthreads.7.html

[@ZebedeusZwalper]

Thanks, will have a look. The main thing is that my code works.

[@MrTega1975]

but from the point of view of operating system process (parent thread) or threads (childs) are the same thing?

[@CodeVault]

No. An operating system will see multiple threads as just one process. While, with processes, the os will actually see multiple processes. This is important, for example, when forcefully terminating a process. If it's only using thread, you only need to terminate that one process, if it's using multiple processes you will have to terminate each one individually

[@rachedbennasr2394]

But why would we ever need to return the values from threads then if they modify the variable in the main scope?

[@CodeVault]

Depends how you want to use it. Usually you can simply assign the result to a global array but, if you want to change something in the caller function's memory then returning is also an option.

[@rachedbennasr2394]

Alright that makes sense Thank you

[@bamberghh1691]

Aren't processes and threads both created with the clone syscall?

[@CodeVault]

From what I can tell, clone creates a new process (doesn't create a thread). www.man7.org/linux/man-pages/man2/clone.2.html

[@shaharrefaelshoshany9442]

best

[@ReactCode0]

sir my vs code not run pthread process

[@CodeVault]

You need to add -pthread as argument to gcc in the build.json file

[@satviksharma6102]

I have a doubt .... In thread code you have declared x globally and in process x was declared locally , so if x was declared globally in process function its value would have changed after incrementing

[@CodeVault]

It wouldn't have changed since processes don't share memory (even global memory)

[@satviksharma6102]

@@CodeVault Thank you this has been a great learning experience

[@nischalsehrawat2130]

Hi where would you use a process and where would you use threads?

[@CodeVault]

If you want to do any computing in parallel you would usually use threads. If you need to execute certain other programs within your program you would use processes.

[@nischalsehrawat2130]

@@CodeVault Hi, I was watching another video and there the presenter said that multi-threading is used for IO intensive task such as reading, writing data and multi processing would be used for processor intensive task such as computations. But I didn't fully understand it. Is it correct what he was saying?

[@CodeVault]

No, that's not at all correct. Both can be used for processor and IO intensive tasks. Can you send the video to me? Maybe he meant this in a specific situation?

[@nischalsehrawat2130]

@@CodeVault kzbin.info/www/bejne/nHzPY32NlNalqdE

[@nischalsehrawat2130]

somewhere around timestamp 39:50

[@kubraaksu733]

why fork did not give the result 0?

[@CodeVault]

It did for the child process. Although here I am outputting the process ID which is not the same as what fork() returns

[@kubraaksu733]

@@CodeVault i get it, thank you for answer!!

[@ansharora3248]

Didn't know Jesus looked like this.

[@user-gx9lr2mh2i]

Summary Thread share memory, and they in the same process. to make two processes you have to fork one, to make two threads you have to make two threads. This kind of unfair video because the diffrences are huge, and you covered only small part of it. (it's not mentioned)

[@matzacomn]

Cred ca esti roman :))) Haha, facui putin stalking Daca da, sa-ti dea Dumnezeu sanatate ca nu mai este NIMENI pe net sa explice lucrurile astea atat de bine si nici la facultate (in US) nu ne explica, nici in cartile recomandate nu gasim cine stie ce :))))) Nu pot sa cred, haha

[@CodeVault]

Mersi. Da, sunt roman. Era foarte greu de inteles modul in care se explica la facultate. Tot timpul mergeau prea in detaliu si se bazau prea mult pe teorie. Fix de asta am facut aceste video-uri

[@matzacomn]

@@CodeVault Suntem multi in grupa care ne uitam la videoclipurile tale. Numai bine si succes in tot!

[@kiseijuu7420]

is it better to fork and creat threads in the fork, or creat a thread and fork in that thread?