Concurrent Collection Interview questions and Answers for experienced and freshers | Code Decode

This video contains Concurrent Collection Interview questions and Answers for experienced and freshers Candidates.
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Concurrent collection IQ Part 2 : • Java Tricky Concurrent...
Concurrent collection is a very important topic in terms of collection interview questions and answers for experienced and answers
Q) Difference between Synchronized Collection and Concurrent Collection?
Both Synchronized and Concurrent Collection classes provide thread-safety
The differences between them comes in performance, scalability and how they achieve thread-safety.
Synchronized collections like synchronized HashMap are much slower than their concurrent counterparts e.g. ConcurrentHashMap, Main reason for this slowness is locking;
What is the need of concurrent collection
Traditional collections are not thread safe. only few classes like Vector, HashTable are thread safe.
Collections provide some methods like synchronizedList, synchronizedMap, synchronizedSet those provide thread safety but problem is they capture lock on complete collection even for reading that decreases performance.
In traditional collection if one thread iterates and other tries to modify structural change then ConcurrentModificationException is thrown.
Give few concurrent collections classes ?
ConcurrentHashMap
CopyOnWriteArrayList
CopyOnWriteArraySet
Why performance of ConcurrentHashMap is better than HashTable and synchronizedMap ?
In HashTable and synchronizedMap lock is acquired on complete collection so only single thread can capture lock at a time while in ConcurrentHashMap lock is acquired on bucket level so at a time multiple thread can capture lock on different different bucket.
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[@akshayengineer2018]

This is the Best video on Concurrent HashMap on whole internet. We cant find such explanation anywhere else, Thanks alot Mam 😊

[@CodeDecode]

Thanx Akshay 😊😊

[@rituparnadeshpande3821]

This is the best video on CHM so far... Every video of yours are clear, to the point and well structured.. You explain very well.. This is a very dependable channel.. Thank you

[@CodeDecode]

Thanks Rituparna. This means a lot 🙂🙂👍👍. Thanks a ton 🙂

[@sneharaghuwanshi4933]

thank you so much for clearing all the doubts

[@suryadoynandan9684]

Thank you so much for upolading such a useful videos...this is helping a lot to clear my logic

[@CodeDecode]

Thanks Suryadoy. 🙂🙂👍👍

[@ILuvBilli]

One important point you forgot to add that we can change legacy collections structure through iterator remove method.

[@muralir6768]

Nice and expecting more videos like this

[@CodeDecode]

Sure Murali 🙂👍

[@madanmohanpachouly6135]

Clear explanation .. Thanks

[@CodeDecode]

Thanks 🙂

[@venkatb8317]

Yes please make video thanks in advance

[@CodeDecode]

🙂👍

[@nagireddy1507]

Great explanation...

[@CodeDecode]

Thanks 🙂

[@rishiraj2548]

👍

[@prinkpalsingh5028]

Really helpful.
Can you please make part2 of concurrent collections

[@CodeDecode]

Sure Prinkpal 👍👍🙂🙂

[@yoshitamahajan353]

is there any video for segmentation which u have made.. wanted for refernece

[@kumaraditya9986]

Please make a video on why null are not allowed on concurrent hashmap.

[@vickybhoir3017]

nice explaination

[@CodeDecode]

Thanks 😊

[@venkataraghava3173]

very nice explanation

[@CodeDecode]

Thanks Raghava🙂👍

[@PradipYogi59]

Wonderful and really great video , can you please share me some good collection books . So I can refer
And please make more video on OOPS and collection

[@lohitharg621]

If one thread is accessing the value then on the same bucket other thread cannot modify right then how will it return null?

[@iloradas6387]

Great explaination but can you please explain modcount concept in a bit more detail

[@CodeDecode]

Sure llora we will do that👍👍

[@sandeepgattu5690]

Please provide the copyonwritearraylist internal working
That will helps us more...

[@shankardayal6928]

As for read ,there is no lock.
Then say s0 is locked for writing then why does reading not allowed in s0?

[@Iam_Raam]

Hi, why won't we get ConcurrentModificationException if we are iterating through ForEach loop and updating map during iterating..?

[@CodeDecode]

Can you please give a snapshot of your code so that we can explain you

[@hemantanahak5674]

KIndly Please share the program to understand the concurrent hashmap where it is not allowed null and concurrency level program as well with bit more explanation.

[@CodeDecode]

Sure we will do that Hemanta 👍👍🙂🙂

[@DilaGurung]

I didn't get the fact since ambiguity is not allowed so concurrent hashmap does not allow null value. But why is hashmap allowing ambiguity.

[@pvc7995]

Make some real time projects mam and how to integrate front end and back-end .. And deployment of project and bug fixing concepts pls

[@CodeDecode]

Sure Thulasi 👍👍

[@dpkpk1573]

Nice explanation....

[@CodeDecode]

Thanks 🙂👍

[@dpkpk1573]

@@CodeDecode if possible please also make a Video on creating Custom annotations in java....

[@CodeDecode]

Nice topic , yes we will create one🙂🙂👍👍

[@venkatsai2541]

Program why null not allows in concurrent hashmapcode while allowed in hashmap please explain by debugging code

[@CodeDecode]

Sure

[@Iam_Raam]

If we are iterating through forEach, we will not get ConcurrentModificationException but we will get if iterate through iterator, why ?

[@ShinAkuma]

You are creating an Iterator reference before using it. So while you're traversing the Map and changing it, your Iterator reference is still the old one which was created using the Map which had lesser values.

[@shijipaul2]

Can you please add one video on deployment process

[@CodeDecode]

Sure Shiji 👍👍

[@dhirajbibekar2944]

Please create and upload part 2

[@CodeDecode]

Sure we will create one soon

[@sharvarirg984]

Ma'am, You have mentioned t2 can't do read or write on segment 1 at 10:50 . But at 17:00 you said read can happen anywhere, segment does not matter. I'm confused. It would a great help if you help me understand.

[@pavithraakp2067]

Read doesn't need any lock. One thread is writing on a segment at a time another thread can read that same segment. Last update value will be returned by get() method.

[@samyishere2382]

Mam can you please make video on tricky interview questions of OS🙏

[@CodeDecode]

Sure we will plan and upload it soon

[@viji6131]

Hi. Can u pls make a video on hibernate pls cover n+1 problem and cache concepts pls

[@CodeDecode]

Very nice topic viji. Will create video on that very soon.

[@tulasiramsunkara]

Can you create a separate video to explain concurrency level

[@CodeDecode]

Sure Tulasi 👍👍

[@tulasiramsunkara]

@@CodeDecode Thank you for considering

[@premamalar8550]

Mam in 13.26 timing.. In that slide t1 check the condition and t2 delete the key u said that na.... My question is t2 for delete operation is our assumption?? Is it correct mam??

[@CodeDecode]

Yes

[@premamalar8550]

@@CodeDecode thank u mam.😊

[@patnalajahnavi1680]

Can u explain reentrant lock clearly

[@smitchaudhari9783]

Hello Mam if null is not allowed the it suppose thread1 is checking so we have lock on that segment then how can thread2 delete it so there can’t be the case where null means thread2 deleted it hence null should be allowed?

[@ashish7516]

Thread1(first one) is just reading, so no lock will be acquired. Hence the second thread (the one writing) can come and delete the value.

[@venkatsai2541]

Please cover array list

[@CodeDecode]

Sure Venkat 👍👍

[@venkataraghava3173]

can you please exp about semaphore

[@CodeDecode]

Sure Raghava

[@kazaasekhar]

we don't have chance to give more than one like otherwise my likes count will be one thousad for every videos...

[@CodeDecode]

This means a lot Sekhar 🙏🙂👍👍👍👍

[@Ravikumar-gj6qw]

create a video at time 13:25

[@geekaffairs6475]

👍

[@CodeDecode]

🙂