Concurrency vs Parallelism

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Concurrency and Parallelism are two terms that are often used in relation to multithreaded or parallel programming. Concurrency and parallelism may seem to refer to the same or similar concepts on the surface. However, they are typically used to specify different types of multithreaded behaviour. In this Concurrency vs. Parallelism video I explain what the difference is.
Chapters:
0:00 Concurrency vs. Parallelism Introduction
0:26 Concurrency
2:03 Parallel Execution
3:01 Parallel Concurrent Execution
4:39 Parallelism
7:26 Combinations
Concurrency vs. Parallelism - Textual version:
tutorials.jenkov.com/java-conc...
Java Concurrency Tutorial - Text / Video:
tutorials.jenkov.com/java-conc...
• Java Concurrency and M...

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Опубликовано:

28 июн 2024

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Комментарии : 136

@markojovanovic8444 3 года назад

Taking off your time to tech other and make it totally free, is a virtue to admire to. Thank you for your awesome tutorials and your time. :)

@JakobJenkov 3 года назад

You are welcome! :-)

@ricardoarrobo9528 13 дней назад

I really liked the graphics on this, as a visual learner it makes it easier to follow.

@JakobJenkov 2 дня назад

Great !! 😊

@shubhamagarwal1434 Месяц назад

God of Concurency..i have bene flowing you since my 2014 when you used to write blog post only...by going through your post i attend interview like a LION when they ask mutithreading qns...Thanks a Lot form 10+ yrs exp guy from BLR,India.

@JakobJenkov Месяц назад

Thanks :-)

@tirthankarmitra2898 2 года назад

First of all Thanks a ton for all these excellent elaborated contents, it is truly admirable. On the context of "Parallel not concurrent" I think we can say that multiple instances of an application could run in parallel however in each application there is only one thread.

@JakobJenkov 2 года назад

True. Multiple processes could run in parallel - even if each process only has one thread running internally.

@vamsi1701 3 года назад

I tried to understand this topic many times till now. This time I have confidence that I can explain others well, because I understood the concept. Thanks Jakob.

@JakobJenkov 3 года назад

Great! :-) ... I have tried myself to have problems understanding a topic - until I found the "right" explanation - one that I understand, that is! I am happy to be able to help others get to that point too :-)

@_graymatter__ 3 года назад

I will come back and watch this once I am done with office work. Thanks for all the good work. Cheers

@JakobJenkov 3 года назад

You are welcome! :-) ... I'll hold a warm copy of this video for you for when you return ;-)

@_graymatter__ 3 года назад

@@JakobJenkov Thanks. The world has turned cold and drab in most places. Little warmth is always appreciated :)

@shihore 2 года назад

Recently I am taking the Parallel and Concurrent Programming course. Your explanation is very clear and thank you for making the video to let me have the basic idea before the course.

@JakobJenkov 2 года назад

You are welcome! I am glad my video helped you! :-) ... I have a whole playlist of 21 videos in this topic - in case you are interested ;-)

@lupuionut6286 3 года назад

The Java concurrency playlist is helping me get through college homework (thank you for that). They're well made and easy to understand. I do also appreciate that an experienced programmer like you decided to do this work basically for free.

@JakobJenkov 3 года назад

I am glad you like them! :-) ... that's why I made them :-)

@manOfPlanetEarth Год назад

@@JakobJenkov Hello, Jakob) Last section, you talking about "parallel, not concurrent" case. Question: if one big task is broken into tasks (in differents threads of course), but there is only one CPU, will it be concurrency and not parallelism?😁

@LuneAgent 2 года назад

It's so satisfying to watch the tutorials in 4k

@JakobJenkov 2 года назад

Glad you think so ;-)

@juanandrew1356 Год назад

Mr. Jakob, your explanation is very good and I understand much better now for my Golang learning. Thank you

@JakobJenkov Год назад

Great ! :-)

@nfuryboss 2 года назад

Very well explained. In most real-world applications with multicore CPUs, it's a mixed concurrency and parallelism. So "parallelism" can be interpreted as a situation where you have a high percentage of parallel executions over concurrent executions. Vice versa. I think the concept of simultaneity of executions flow is important here.

@JakobJenkov 2 года назад

Thank you. Yes, there is a lot of parallel execution going on in multicore CPUs. Some threads may run on the same CPU, other threads may run on different CPUs etc. Additionally, you have the serially parallel instruction pipelines of the CPUs too, that also provide some level of parallelism - although within a thread - not between threads.

@AMITPAUL-ty1hk 11 месяцев назад

Well explained Jakob. Thanks for explaining the complex concept in a simple way...

@JakobJenkov 11 месяцев назад

You are most welcome ! 😊

@alessandroporfirio1910 3 года назад

Thank you for this video. It was very well explained.

@JakobJenkov 3 года назад

Thanks :-)

@ralphguichette9952 Год назад

FINALLY! Every tutorial and course I've taken could not explain this the way you just did. Rule: "If you can't teach it to me like I'm 5, you don't know it either". You sir, clearly know your stuff. Thank you! Please tell me you have courses I can buy from you.

@JakobJenkov Год назад

Thank you very much for your kind words! :-) At the moment I do not have any specific courses (or similar) that you can buy. In the future I will probably have some books etc. - but they will most likely be related to a very specific project I am working on. There will be lots of basic to advanced stuff to learn from those too, though. But - not yet :-) You will see when it comes out - because I will be making videos about this project too :-)

@gabrielxu2087 2 года назад

Best concurrency tutorial online!

@JakobJenkov 2 года назад

Thank you! :-)

@athisii_ekhe6167 2 года назад

Thank you for making it very clear. Great job!

@JakobJenkov 2 года назад

Thanks - and you are welcome! :-)

@aktchungrabanio6467 3 года назад

Excellent! So clear. Thank you.

@JakobJenkov 3 года назад

You are welcome! Glad it was easy to understand :-)

@sonofgod00 3 года назад

great explanation for all. thank you.

@JakobJenkov 3 года назад

Thank you - and you are welcome :-)

@bitcoindaddy748 3 года назад

Marvelous explanation, thank you!

@JakobJenkov 3 года назад

You are welcome :-)

@lukashenrique4295 3 года назад

"daddy, can i get a bitcoin pleasee?" idk why, I just thought that when I saw your name lolll

@rajankumarverma507 Год назад

Great work, thanks for helping on Java.

@JakobJenkov Год назад

Thanks - and you are welcome! :-)

@lukashenrique4295 3 года назад

beautiful graphics. ty so much for the explanation!

@JakobJenkov 2 года назад

You are welcome ! ... Hope it was easy to understand! :-)

@bunthaideng2492 6 месяцев назад

That's awsome Jakob!

@JakobJenkov 5 месяцев назад

Thank you !! 😊

@sandyfernando9600 2 года назад

Thank you for the clear explanation !!!!

@JakobJenkov 2 года назад

You are welcome!! :-)

@jayaganthan1 10 месяцев назад

Awesome explanation! Thanks

@JakobJenkov 10 месяцев назад

You are welcome! :-) Glad to hear its useful!

@nolanbyrnes8505 3 года назад

Well explained! Thank you!

@JakobJenkov 3 года назад

Thanks, and you are welcome 😊

@nazeeyashikalgar2428 3 года назад

Nice explanation! Please make more videos about latest concurrency api introduced in Java.

@JakobJenkov 3 года назад

I will try :-)

@emonymph6911 3 года назад

Literally 0 dislikes speaks for itself... You're a god!

@JakobJenkov 3 года назад

Thanks :-D

@ffatheranderson 3 года назад

Thank you very much Jakob.

@JakobJenkov 3 года назад

You are welcome! :-)

@krishnamurthymadaraboina1556 8 месяцев назад

thank you , i undersood this concept now.

@JakobJenkov 8 месяцев назад

You are welcome :-)

@masoomsanadi 10 месяцев назад

nicely explained. simple & neat

@JakobJenkov 10 месяцев назад

Thank you ! :-)

@antonhen23 3 года назад

Jakob, you have explained well the difference between concurrent and parallel execution in terms of CPU processes. But is there any difference in terms of sharing data? Is it possible to create 2 processes running on the different CPUs sharing the same data like counter variable, and the process is to read the value and inc it. I guess in previous videos when you're talking about 2 Threads sharing data, these 2 processes were executing on the same CPU concurrently. Is it possible that those 2 processes could have been executing on the 2 different CPUs in parallel? How synchronized block manages threads(processes) sharing data but running on the different CPUs?

@JakobJenkov 3 года назад

Yes, it is possible to share data between threads that run on different CPUs. And yes, volatile and synchronized keywords work the same in that situation. If you access a variable from within a synchronized block, only one thread can access it - regardless of how many CPUs your computer has running threads inside your application. Also, you are guaranteed that updates made by one thread to a variable from within a synchronized block is also visible to other threads - even if the threads run on different CPUs. The same is true about volatile variables.

@antonhen23 3 года назад

@@JakobJenkov Thanks! It's clear now)

@shivam8837 Год назад

Awesome explanation

@JakobJenkov Год назад

Thanks ! :-)

@maxisperera3024 2 года назад

Thanks SIR !! for the Great effort !!!

@JakobJenkov 2 года назад

You are most welcome! :-)

@webizfabulous2535 6 месяцев назад

thank you! Love this video! Take care.

@JakobJenkov 5 месяцев назад

You are welcome, and thank you too !! 😊

@manoj.tyg01 3 года назад

Thanks for making video on this topic...enjoyed more than the blog :-)

@JakobJenkov 3 года назад

Thanks! Glad you like this one Manoj! Long time since we talked the last time, right? Usually on LinkedIn... :-)

@manoj.tyg01 3 года назад

@@JakobJenkov Yes, last time we talked on LinkedIn as you don't like social networking much facebook or whatsapp :-) I think study pattern is changing now.People are more interested in video content as video maker can express more as compared to blog and Listener can also play with any speed he/she likes.Earlier I used to keep 1.x but now I am comfortable with 1.5 or sometimes 2.0 and this is great experience. Hope you will make more content whenever you have time specially on distributed architecture and whatever you have done in last couple of years.

@ashutoshkedar1577 3 года назад

clear and concise explanation. Thankyou. Please do make a video on demonstration of java concurrent collections.

@JakobJenkov 3 года назад

Thank you! I may get around to making videos about the classes in java.util.concurrent soon. Until then, I have textural tutorials about them here: tutorials.jenkov.com/java-util-concurrent/index.html

@ashutoshkedar1577 3 года назад

@@JakobJenkov Thankyou

@krishnachaitu17 2 года назад

fantabulous, thanks for the great share

@JakobJenkov 2 года назад

You are welcome! :-)

@umitkirtil Год назад

Thats realy good explanation

@JakobJenkov Год назад

Thank you! :-)

@poosam4065 2 года назад

Good video. Very clear content. :)

@JakobJenkov 2 года назад

Thank you very much!

@WizardOfArc 2 года назад

Thanks for clearing this up for me 😀

@JakobJenkov 2 года назад

You are welcome! :-)

@sanjarcode Год назад

Thanks, awesome explanation. A video Idea - Concurreny vs Parallelism vs Asynchrony.

@JakobJenkov Год назад

Java does not have async await features - if that is what you are referring to.

@renandorneles3217 10 месяцев назад

Damn, nice video!

@JakobJenkov 10 месяцев назад

Thank you 😊

@iragideonkane4045 2 года назад

Thanks a million

@JakobJenkov 2 года назад

You are welcome! :-)

@muhammaddevanozaidan6837 Год назад

nice explanation

@JakobJenkov Год назад

Thanks :-)

@naej2549 3 месяца назад

this video is awesome

@JakobJenkov 3 месяца назад

Thank you very much !! :-)

@boscooludhe7406 3 года назад

Nice Explanation

@JakobJenkov 3 года назад

Thanks :-)

@akshatjain3010 11 месяцев назад

Thanks a ton or the excellent video! Could you please help me understand in case of Parallelism splitting of a task(thread) done in the program(By Programmer, is so how?) or it is done by the compiler while generating the machine code or CPU while executing the instructions?

@JakobJenkov 11 месяцев назад

Splitting a job up into multiple smaller tasks that cen be processed in parallel must be done by the programmer. The compiler does not know enough about the tasks your code is performing to know how to do that, in most cases. In some cases, if you give some hints, perhaps it can be done more automatically - and sometimes at runtime by e.g. TornadoVM or other tools. But the developer is at this point in time still required to at least hint at how to break up the task.

@akshatjain3010 11 месяцев назад

@@JakobJenkov What are the ways in programming through which a task (Thread) can be split into multiple subtasks? If you can give any hint in any language.

@jolskey Год назад

Hi Jakob. What do you exactly mean in CPU? Do you use CPU and CPU core interchangeably? Because as I know, computers usually come with one CPUs and multiple cores. So let's take Intel Core i7, is i7 a CPU or it has bunch of CPUs? Thanks.

@JakobJenkov Год назад

In terms of multithreading just think multiple cores. I don't think it makes a huge difference concurrency-wise whether you have one CPU with 8 cores / 16 threads, or 8 CPUs. You have to deal with the same issues.

@SyedGm Месяц назад

@Jakob, do you have git repository for all these tutorials of threads ? the examples which you are explaining in the videos.

@JakobJenkov Месяц назад

I have some examples in my Java Examples GitHub repo (link below) - but not yet so many: github.com/jjenkov/java-examples

@aghiadalzein3069 2 года назад

That was great....

@JakobJenkov 2 года назад

Thanks! :-)

@KeplerEmeritus 2 года назад

Good video! Only thing I think is that "CPU" could say "Core" in the example images.

@JakobJenkov 2 года назад

True... but I decided to keep it simple :-)

@yuzheding4436 2 года назад

omg, this is so clear

@JakobJenkov 2 года назад

Thanks! Glad it was understandable :-)

@rajankumarverma507 Год назад

Hi jakob, can you please create any course on how to do real time project development for experienced Java developer for production ready project. It should have source code for real time Java project. Thanks for this video.

@JakobJenkov Год назад

Hi Rajan, I will eventually make some videos about Realtime Architectures - but it's a big topic with lots of details, nuances and tradeoffs, so I don't think I can just make a "ready-to-go" template you can just start from. But I can cover various topics that can help you design your own realtime architecture, or at least take steps towards a realtime architecture.

@sjm2256 Год назад

would you say that parallelism is the same as parallel concurrent execution, except its concerned with a single task being broken up rather than different tasks?

@JakobJenkov Год назад

That is my understanding of the official distinction, yes. Approximately.

@eternalgreed6715 Год назад

Hi, Jacob! If i have 1 core(CPU )CPU and run 2 instances of the same application with only 1 thread (main) in each instance, does it mean parallel execution? Or Parallel execution of any application, process might be only on 2+ cpu? Sorry for possible obvious question.

@JakobJenkov Год назад

Parallel execution would require more than one CPU. Otherwise it is just concurrent execution

@JakobJenkov Год назад

Or at least more than one CPU core...

@webmaster246 2 года назад

Has Parallelism to do anything with fork() specifically for Node.js ?

@JakobJenkov 2 года назад

I am not an expert in Node.js - but I think fork() runs a JavaScript in a new process - which might be able to run in parallel with the process spawning it. But - please double check the Node.js docs !!

@naej2549 3 месяца назад

I am having so much fun right now

@JakobJenkov 3 месяца назад

Great! :-D

@emonymph6911 3 года назад

Does anyone know if any of these three backend languages have both concurrency and parallelism? Node/Express Django Go I want to become a multi-thread API dev. I don't care about what is 'popular' now. I just want what has the best foundation for concurrency and parallelism.

@JakobJenkov 3 года назад

I don't know myself, actually. I vaguely remember something about Node having support for multiple threads that can run on multiple CPU cores, but I don't know how it works internally.

@omnipoten8 3 года назад

Thanks for the nice explanation . I have got a question here . If we have two threads and two CPUs. CPU-1 is executing thread-1 and CPU-2 is executing thread-2. Hence we have parallelism here. Now if at some point of time one of the threads takes the monitor of a lock and halts the execution of other thread until the monitor is released and acquired by other thread, in that case which one is true : 1. Thread-1 and thread-2 are running concurrently 2. Thread-1 and thread-2 were running in parallel , but at that point of time when monitor lock was acquired they ran concurrently . 3. Thread-1 and thread-2 are running in parallel

@JakobJenkov 3 года назад

If Thread 1 takes a monitor object, and Thread 2 does NOT try to take that monitor at the same time, Thread 1 and Thread 2 are still running in parallel. If Thread 2 DOES try to take the monitor object while Thread 1 holds it, Thread 2 will be blocked until Thread 1 releases the monitor object - in which case they are not running in parallel while Thread 2 is waiting.

@omnipoten8 3 года назад

@@JakobJenkov Thank you very much Jacob for your reply . Very clear and concise .

@jeromebarbier5295 2 года назад

Concurrency looks like async JavaScript. Did I miss some key difference here?

@JakobJenkov 2 года назад

Not exactly. Async in Java still runs within a single thread, as far as I know. Concurrency in Java could be achieved using multiple threads - yet still running on the same CPU (or different CPUs).

@jeromebarbier5295 2 года назад

@@JakobJenkov I see. Thank you.

@AhmedMohamed-mq2xz 2 года назад

When you say CPUs do you mean CPU cores?

@JakobJenkov 2 года назад

Does it matter?

@AhmedMohamed-mq2xz 2 года назад

@@JakobJenkov First of all, please excuse my lack of knowledge as I'm still learning. I believe it matters because it sounds odd to say: Imagine we have a computer with 2/multiple "CPUs" 2:10 3:19 instead of the commonly known "CPU Cores" with 2 Threads each. I first thought this might be possible with dual CPU servers, which you didn't mention, until you mentioned "8 CPUs" 6:37 . I'm only pointing this out because I got confused and wanted to get more clarification.

@cclementson1986 12 дней назад

You tried so hard to be clear but you failed and even in the comments you are sticking to it. People are asking, do you mean CPU or CPU core. It matters!!! Stop saying it doesn't. The average person does NOT have a multi CPU machine. So it matters. By not CLEARLY defining what you mean, it causes more confusion, especially to those trying to learn the VERY difficult concept. Say what you mean, say CPU Core. It means something.

@JakobJenkov 2 дня назад

Allright - I will say CPU core in the future... I don't personally think it makes a big difference, except a bit about the internal design with caches etc. But I can refer to the cores as "cores" ... We are also getting a GPU API in Java in the future, and I guess we also just call it "one GPU with many cores".

@cclementson1986 2 дня назад

@@JakobJenkov I appreciate your response. I really liked your video but I did have to look at a couple more to fully understand that you meant CPU core. Thank you for taking the time and being willing to adapt. As a consumer of content, I can only appreciate those who are willing to accept feedback and adapt. Thank you for your response.