Your channel is beyond any praise .

No amount of appreciation is adequate. The way you relate textual, monotonous OS concepts with real life scenarios is amazing. Keep up the good work.!!!

those were the clearest 9 minutes of my whole day

Thanking you for these videos is different, but Oracle's JDK team should pay you. YOU are THE ONE who has put these concepts into such clear and neat explanation allowing people to use it the way it's supposed to be. Java docs make sense only after going through your videos! I know the effort it took me 5 years ago, to understand Java5 concurrency concepts. My brain used to bleed through my nose, ears :P every time used to read, java doc and different articles to get the grip of these.

This channel nailed it really, your easy way of teaching make complex topic like cake walk.

after 3 days of searching content finally i found you! thanks alot ! super clear explaination and great tips

This made me actually understand some concepts in Golang better. You are awesome.

I like your way to simplify the problem and use non-ambiguous terminology and examples to explain it in the simplest possible way. It reduces the need for lots of cognitive effort. A lot of people teaching online completely fail at this point.

Great explaination of the concept. Thanks a big bunch.

You make it all look so simple! You're the best.

The quality of explanation here is very high, amazing stuff, thanks so much

number of likes deserve to be same as number of views. you are a champ. love to watch your videos and learnt something new each time I watched your videos. please don't stop uploading videos.

This is really an awesome explanation. Thank you very much!

One of the best explanation on YT, right now. Thanks bro

Excellent . Your explanations are very clear and concise .

Excellent.. simplicity at its best 👌 God bless you 👍

You're very good at explaining things.

Superb explanation. I was looking topic like this. Thanks a lot

Thank you so much! Such a good and clear explanation, I finally understood this topic :D

Great content! Definitely going to watch whole concurrency playlist, having watched a couple of videos from it I'm sure it will not disappoint.

Really liked your videos. Awesome explanation.

simple, clear and great explanantion, thank you!

Awesome Explanation! Thanks!

Such an awesome video, why there are no videos off late? I started understanding concurrency only because of you!

Love your teaching style. Make very easy and understandable

It was a pleasure watching and listening to this one.Thanks a lot!

@DefogTech

6 жыл бұрын

You're welcome sir!

Simply amazing explanation.

Awesome...Clear and Consice...

Great video, thank you!

As always, very good video. 👍🏼

Thank you very concise explanation ..

Awesome. Very interesting videos on java concurrency

great video and I encourage to make more videos like. you are doing a great job

Great tutorial, Dude

This channel is a gem in terms of practically explaining java concurrency principles. Thanks ^ thanks. Nowhere have i come across such lucid explaination of these things.. i have learned most of these hard way.

@ArchitGupta0x2B

4 жыл бұрын

One question wrt to this video. Can we acquire semaphore on one thread and release it in another. I know this is required for locks.. but what in case of semaphores?

@DefogTech

4 жыл бұрын

Yes, you can.. but i don't know of any use cases where we would need that. Semaphore is mainly for coordinating how many parallel threads can do some tasks

Very good that explanation !

Good job!! Could you talk about the bias locking mechanism?

Nice video, fan Ho Gaya aapka, Please do the same other locking mechanism like mutex

Simply Awesome

It is also worth noting that semophore operations of incrementing and decrementing the count of permits are synchronous.

Before watching this video,to understand semaphore precisely was a nightmare for me... Excellent explanation....

Great ..Thanks

amazing explanation,

good job !!

Awesome !!!!!!

Very good video

Excellent Content @Defog. I had one question , whatever the semaphore is doing , we could have done the same , if we would have mentioned the fixedThreadPool size as 3. Then internally only three thread at a time could have accessed the shared resource .Or is it like if the the 50 other threads which you instantiating the in the executor, they also have some other tasks(independent) before they hit on the slow service ?

Excellent explanation!! if possible, can you please talk about reentrantcy?

@DefogTech

6 жыл бұрын

Sure, give me few days please, will make one about locks' features like re-entrancy, fairness and such.

Awesome

Instead of blocking threads you can also put the task in a queue and process that queue with a 3 threads pool. It has also less Synchronisation overhead. Only downside is if you need multiple critical sections like that you get too many pools. And don’t forget to put release in a finally block

Nice Video sir, please provide some more videos on Threads. Thank you so much for sharing your knowledge with us. Keep it up good work.

@DefogTech

6 жыл бұрын

You're welcome! Btw, how did you watch the whole video so quick, I uploaded it literally 3 minutes back :)

@corabora6644

5 жыл бұрын

Defog Tech he mustve had a Semaphore lock on it

Nice video. Just to add...It is best practice to use try-catch for acquire/ release

@DefogTech

6 жыл бұрын

Agreed. Especially for release.. similar to lock.unlock()

superb

it is nicely explained,here i have a question which is subtle,if the thread calls the release() method and then semaphore has available permits, then the thread which released the lock will go back to the thread pool

your thumbnail is so aesthetic.

Goo explanation. One point though. Shouldn't aquiring and releasing the permits follow the try/finally idiom as an excetpion thrown while holding the permit can never be returned

This is the only place I got to understand such complicated things in bread and butter manner.

Classic 👍

cant we use fixed thread pool with size 3 rather than semaphore ?

To create a stream of 1000 counts and submit task , use IntStream.range(1,1000).forEach(i->service.submit(new Task())); rather than Instream.of(1000) as this provides a stream of only one number i.e. 1000.

@DefogTech

5 жыл бұрын

You are right. Thanks for pointing out!

@moratorium33

5 жыл бұрын

@@DefogTech lol Nice video, but this confusing me though

@ofa822

2 жыл бұрын

Nah, this is incorrect because the second argument of range is exclusive and since you are starting it from 1. Total number of tasks will be 999 and not 1000. You need to use rangeClosed(1,1000).

Thank you vm

Any use-case on why would thread want to acquire multiple permits from semaphore ??

thank you ...

@DefogTech

5 жыл бұрын

You're welcome!

Overloaded method of acquireduninterruptably , what can be a use case for this sir ?

IntStream.of(int) would create stream of single integer, not 1000. In this case only one task is submitted

@DefogTech

4 жыл бұрын

yeah thats right, was my mistake.. unfortunately cant edit video

Are connection pool are made the same concept...

Thank you for these videos. I'm thinking can semaphore be replaced with fixed thread pool? If I replace semaphore with fixed threadpool, the locking may not be within the code, which'll be far away and may not convey the intent. Having said that dynamic permits aren't possible with fixed thread pool. But for simple permits I'm assuming that semaphore can be replaced with fixed threadpool. No of permits = no of threads. What do you say?

@DefogTech

Жыл бұрын

Yes you can! Though idiomatically, every lock/semaphore etc should remain close to the resource which is being accessed. Going one step further, its better to encapsulate that object and expose methods which internally use semaphores to guard access. This will ensure no other threads apart from our ThreadPool can ignore the semaphore condition (eg: Web serving thread pool)

We can achieve the same functionality if we have only 3 threads in fixed threadpool? . So what is the difference?

@DefogTech

6 жыл бұрын

True. But what if your tasks have some condition before calling the service (so tasks may or may not call the service). In that case you want to have as many concurrent threads/tasks as possible, and but will need Semaphore to ensure only 3 tasks can call the serve. Similarly, what if there are different types of tasks in a large application which are run by different executor services, or directly by servlet thread pools (which cannot/should-not be restricted). I showed simple example in video to help understand the concept. Generally our applications are slightly more complicated, thus we need such concurrency primitives.

@corabora6644

5 жыл бұрын

Defog Tech Care to clarify a bit more, please ?

@reapi_com

5 жыл бұрын

@@DefogTech In theory the semaphore could be shared across multi thread pools right?

@DefogTech

5 жыл бұрын

Absolutely. Thus, even if there are threads (across pools) accessing our resource, using same semaphore we can restrict the access.

@DefogTech

5 жыл бұрын

Consider example of a legacy payment service which is very slow, and if there are more than 3 simultaneous connections to the service, it just throws out of memory exception.. Lets say in our application we have multiple features using which user can make payments... for memberships, for buying items, for adding money to their wallet etc. All these features lets say have their own thread pool. How do we ensure, that if there are multiple users all trying payments using different features, we do not overwhelm the legacy service. In this case Semaphore is perfect utility to throttle connections to payment service.

spring cloud hystrix is providing this capability....is this a better way or annoation wrapped spring cloud hystrix

@DefogTech

5 жыл бұрын

I don't know about hystrix bring available as standalone process. But if your plan is to only use circuit breaker and no other features of service mesh then it's better to use annotation based code and not separate process

Sir would u plz provide a vedio on reentrent locks in java

@DefogTech

6 жыл бұрын

Yes sir, I am making it.. it might take a while, sorry about the delay.

I am on my windows machine right now (i.e. no IDE), so I will be lazy and ask the question: Can you use this code to totally parallelize the creation of the Runnables? ```IntStream.of(1000).parallelStream().forEach(...``` In the spirit of the topic, I thought this might be a nice touch.

@DefogTech

5 жыл бұрын

Yeah absolutely.. I think it should be intstream.of(1,1000)

In 1 sec if application get 100 requests. If I allow only 3 requests at a time. Meanwhile 3 requests are processing taking a long time then remaining 97 requests are in blocked state?

Hi Nice video. One question what will be the difference between synchronize and semaphore with single count. Aren't these same. I tried to search this online but did not any correct answer. Please help !!.

@DefogTech

5 жыл бұрын

Technically true.. both acheive the same thing. Though in Semaphore, you can timeout on acquire method. In synchronize there is no way to back out.

What happen if I use newFixedThreadPool(3) instead of 50. ? It acts as semaphore then what is the difference ??

@DefogTech

4 жыл бұрын

True but what if it's to be used with web request thread pool.. we don't want to reduce size of that threadpool

What if my application is deployed in many node ,how we can restrict?

@DefogTech

5 жыл бұрын

We will need to use distributed semaphores like concept in redis or similar

I am confused here. Then what is the difference between ExecutionService and Semaphore. It seems they would work the same way. In this case if you create a thread pool of just 3 threads. I think ExecutionService is an alternative to semaphore and a newer API with more features.

@isaurabh2001

4 жыл бұрын

You have launched 100 threads but based on the condition, they may do entire different work. Out of those 100, suppose only 5 needs to access that lazy resource. In your scenario, all the threads doing same job, that is accessing that lazy resource.

Nice presentation...where can I find all these presentations?

Your way of explaining things are very clean and clear . Thank You somuch ..

Very nice explanation. Could you create tutorial on "mutex"? I read many place, "mutex" being referred to as "binary semaphore". I think this is grossly wrong to equate "mutex" to "binary semaphore". Any thread can release a "semaphore", whereas mutex serves exclusivity , and only that thread can release mutex which initially acquired. So I think this is wrong to equate mutex to binary semaphore. Also, what exactly is the of implementation of mutex? Is Lock (e.g. ReentrantLock) a mutex implementation. Can you make a tutorial for clarifying all this?

@DefogTech

4 жыл бұрын

mutex is same a lock. it is basically using any concurrency tool to ensure 2 threads dont access/change a memory (object) at same time.

@vipinkoul9129

4 жыл бұрын

@@DefogTech Your tutorials are crystal clear :-)

@DefogTech

4 жыл бұрын

@@vipinkoul9129 Thanks much!! :)

For how many more days we have to wait for Locks/Reentrant locks videos? :)

@DefogTech

5 жыл бұрын

Maximum 2 more days sir. I have the slides ready. Apologies for the delay

Threadpool or Deadpool ?

If Semaphore is releasing a lock and there are 5 threads waiting how is it decided which thread will get a lock Priority of Thread or FCFS or anything else

@muneeswaranmuneeswaran3768

2 жыл бұрын

At the end of the video, he mentioned a constructor with 'fairness' parameter which allows the long waiting thread to acquire the lock.

Circuit breaker

great explanation of a boring and never understandable topic

I would rather use 3 threads so there would no chance of such problem. Anyways.... Using 50 threads and only allowing 3 threads at a time to run doesn't make sense.

would have appreciated a better and more practical example

good content with clarity of concept. one correction though IntStream.of(1000).forEach will not run loop for 1000 times. its one element

@DefogTech

10 ай бұрын

You are right. It was a miss from my side.

Nice explanation with an even better example. Thanks