Java ThreadLocal

[@wizzard211]

Guys don't get overwhelmed, its a simple Map for threads. Each thread has it's own key and value.

[@shankar7435]

I do agree but it's a luxury to have it and use it without doing all that additional map work. Loved this feature in language. ❤❤❤

[@av98]

You have created one of the best tutorial for multi threading.

[@JakobJenkov]

Thank you very much! :-) Glad it is helpful!

[@shankar7435]

First time i ever felt someone giving correct portion of details for a concept in java using reasonable and correct language usage. ❤❤❤

[@JakobJenkov]

Thank you !! 😊

[@shubhamagarwal1434]

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]

Thanks :-)

[@shobhanksharma65]

When I saw name 'Jakob Jenkov', I immediately remembered a lot of your blogs on your website and I was sure your videos won't be let down as well. And as expected these are great!

[@JakobJenkov]

Thanks - I am glad I did not disappoint you :-D

[@tousif161]

The best tutorial on multithreading. Thanks for making my life easy - was struggling to understand ThreadLocal concept.

[@JakobJenkov]

You are welcome! :-) Great to know my tutorial was helpful to you! :-)

[@gparashar4u]

Great. Clear the of confusion around using ThreadLocal in the thread pool. Thanks.

[@JakobJenkov]

You are welcome! :-)

[@farhaankazi7134]

Thanks, Jenkov, I really appreciate your work. Finally, I understood how the hell Thread Local work without confusion. I read your article. I liked it and that was enough, but it also inspired me to see your vlog and I also saw it. Both of them are really best and worth spending time on both of them

[@JakobJenkov]

Thank you very much for your kind words! :-) I am happy that my tutorials are helpful to you! :-)

[@akshukla04]

Thanks Jakob for posting these videos. I have been following your articles for over 4-5 years now. and Its nice to see you are posting videos on KZbin as well. Java Concurrency has been a painful topic for me. I hope to see more videos from you on Java Concurrency. Thanks Again !!!!

[@JakobJenkov]

Hi Akhilesh, thank you for your feedback! :-) I plan to post several more videos within the Java Concurrency topic over the coming months. Hopefully you will find them useful too :-)

[@abhishekbaghel]

good to see your youtube channel. I have learned a lot from your blogs. thanks for creating your youtube channel. looking forward to your upcoming video

[@JakobJenkov]

You are welcome :-)

[@maluginp]

Thanks, it's awesome guide to multithreading in Java.

[@JakobJenkov]

Thank you - it's still "under development" :-)

[@Golipillas]

Not a single dislike, well deserved, awesome content! 😊

[@JakobJenkov]

Thank you very much! :-)

[@developerscentre]

Best channel for any Java related concepts! Please keep coming with more such contents. 🙂

[@JakobJenkov]

Thank you very much! I've got a video on the Java ForkJoinPool coming out next week!

[@mostinho7]

Thanks for great video Todo: take notes ThreadLocal in a thread pool will let tasks share variables stored in the threadlocal if the tasks are run by the same threads, this may not be what you want Inheritable thread local allow child threads to share values, normal thread local is per thread

[@JakobJenkov]

You are welcome! :-)

[@manOfPlanetEarth]

@@JakobJenkov wow! nice issue!:) Bit of advice: when it'not clear which thread prints null, add pls a string, it's more illustrative. Like: Sout(some_null_var); -> Sout("Thread 1: " + some_null_var);

[@isaiassalles1180]

Dude, I love the content you have in your website and your videos make things even better

[@JakobJenkov]

Thank you very much! ... working on a new video, by the way. It will probably be out next week :-)

[@namigtahmazli7870]

Such a valuable resource. Thank you very much.

[@JakobJenkov]

You are welcome! :-)

[@alanbidu1]

Thank you for sharing knowledge.

[@JakobJenkov]

You are welcome :-)

[@SoeaOu]

thank you for the excellent videos in high quality

[@JakobJenkov]

You are welcome ! Glad you like them! :-)

[@oliveryt7168]

Well done with the presentation and explanation!

[@JakobJenkov]

Thank you 😊

[@kafychannel]

Great tutorial! Thanks a lot. I also read it in text version, love it :)))

[@JakobJenkov]

Great to hear! :-) I am happy my tutorials are helpful!

[@ghettoteacher8713]

Hi there! I have recently finished a grad scheme as a software engineer and find your articles really helpful! Not sure if you’ve heard of the Disruptor library (from LMAX) but it would be cool to see you eventually teach that since it’s pretty cool the way they incorporate mechanical sympathy! Thanks and please do continue creating vids !

[@JakobJenkov]

Thank you very much for your kind words about my tutorials! :-) I am aware of the Disruptor, but it's only one of many ways to achieve high performance samethreaded / singlethreaded style architectures. I may be getting to those later in this tutorial series. I have already discussed many of them on my tutorial website.

[@ashutoshkumarsingh1]

U r awesome man👍🏻

[@JakobJenkov]

Thank you ! :-)

[@antonhen23]

Great lesson!

[@JakobJenkov]

Thanks :-)

[@pubgbattleground9208]

nice video. good work

[@JakobJenkov]

Thank you! :-)

[@pawelchrzanowski8]

very good content

[@JakobJenkov]

Thanks, Pawel :-)

[@mr.swapyyc]

Helpful!

[@JakobJenkov]

Thanks! :-)

[@RaviNagubandi]

Thanks Jakob for awesome content. Can you share the code snippets in your github repository?

[@JakobJenkov]

Eventually I will - but right now they are not shared. It's a time issue... so much to do - so little time! :-)

[@menchomenchev8973]

Hello Jakob. Very well presented. There is a missing piece, however, why does the Threadlocal class is capable of keeping a single value internally per thread that accesses it? and why would we want to to use the class (as a container) in the first place?

[@JakobJenkov]

ThreadLocal is typically used to create thread level singletons.

[@menchomenchev8973]

@@JakobJenkov Thank you, appreciate it!

[@varunupadhyay3836]

The second thread can actually end up seeing the value being set by thread one if we don't include the sleep as part of thread 2. Not sure if its some form of reference leakage or its necessary to remove the value as part of same thread.

[@JakobJenkov]

Two different threads setting variables on a ThreadLocal should always only see the value they set themselves. They should not be able to see each other's values set on a ThreadLocal.

[@almonyplony1280]

To be honest, I didn't understand what is the difference between this ThreadLocal and a regular local variable? What can this ThreadLocal solve for me, that a regular local variable can't?

[@JakobJenkov]

If two threads use the same ThreadLocal instance, they can store their own value inside it. They don't see each other's values. The values stored by a thread in a ThreadLocal is "local" to the thread that stored it. If you just used a standard shared value instead, all threads would see the same variable value - the last stored value by any thread (provided access to the variable is properly synchronized - or the variable is volatile) - not the value stored by the thread reading the variable (as is the case with ThreadLocal).

[@muammaryusuf7083]

@@JakobJenkov, why not user private local variable? is problem solve for syncronize? so... how if we want share same variable for two thread? for example we have shareObject1, i want share those with Thread1 and Thread2? howto solve using ThreadLocal?

[@LuneAgent]

First thing that comes to mind: you can use ThreadLocal to count the number of tasks that each thread has completed. You can have just one variable field that will show different numbers for each thread in the pool when accessed from corresponding threads.

[@Manuel-oe4gv]

@@LuneAgent You can have a local variable inside the thread doing the same thing right?

[@ahmeedev]

Thanks😍

[@JakobJenkov]

You are welcome! :-)

[@MissBlurryFace]

At 13:03 you are mentioning that child thread does not know about the threadLocal but only inheritableThreadLocal. This part is not clear to me? Both the threadLocals have been set in the parent thread yet child only sees the inheritableLocalThread. . Btw thank you so much for these videos.

[@dontwanna6759]

hey jacob i love your java tutorial i am just finishing with core java concepts can you share beginner friendly projects

[@JakobJenkov]

I have more beginner friendly tutorials on my tutorial website, here: tutorials.jenkov.com/

[@muammaryusuf7083]

If only for save and get data for locally thread, why not use local variable instead?, can you tell me when ThreadLocal usefull usage?

[@JakobJenkov]

If you have an object that is being called by more than one thread, and you need to keep some state in the object between calls, and you don't want that state shared between the threads, then using a ThreadLocal instead of a normal member variable (AKA field) can solve the problem.

[@muammaryusuf7083]

@@JakobJenkov , great... thanks very much....

[@threadRunnable]

why to use threadlocal if we have local variable to use?

[@JakobJenkov]

ThreadLocal is not for local variables, but for member variables in objects that are shared among threads - but which should be "local" to each thread.

[@mehedihassan5184]

Best

[@JakobJenkov]

Thanks 😊

[@liu-zl9df]

good man

[@JakobJenkov]

Thanks :-)

[@ersachin1204]

sir how to create KZbin downloader in android studio ?

[@JakobJenkov]

I don't know, unfortunately!

[@subashsakthivels8808]

Good video, but it's make me sleep

[@JakobJenkov]

Thank you! ... sad my tone of voice makes you sleepy :-) ... I am trying not to speak too fast, so as many as possible can keep up. By the way, you can play the video in 1.25 or 1.5 x normal speed - maybe that helps?

[@manOfPlanetEarth]

@@JakobJenkov :)) Now i am playing at 0.75x speed and with subtitles in order to think over what was said.

[@oliveryt7168]

I actually like the way he talks... like a normal human being...