FANG Interview Question | Process vs Thread
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This is how video lessons should be done; plenty of diagrams and animations instead of someone just talking.
Thanks!
Building a house is a process, but the people doing the work to install the pipes, paint the walls and do the electrical work are all the working threads within the process of building the house.
I like to use threads synonymously with “unit of work” or “thing that executes a specific piece of work / action for the process to complete successfully.
So if I run chrome, and have 10 tabs open, I will have 10 processes running. Within each process are 1 or many units of work (called threads) responsible for memory management, access, logic, etc.
I believe the house analogy works well in a lot of cases
Also, I was asked this question in an interview during a Comp. Sci. Fundamentals round during the systems design portion of my interview process at a large, global company we all interact with daily. (Keeping vague for obvious reason)
brov why don't you make a video the house example is very brilliant
Thread is the mechanism of sending instructions from a program(process) to CPU. Threads are OS based mechanisms, also processes are too but a process includes at least one thread. You can imagine that a process is encapsulation of a thread or threads. The OS looks at the program(when you click an executable), creates an executing process for the execution of the program and in the process the thread or threads are the carrier of instructions which are sent to the CPU. This is the execution mechanism of a program in an OS. When you create a thread rather than the main thread, you say to the OS that in this thread those instructions should run in a different context, that will create a context switch(that is execution of instruction(s) given by a thread to the CPU in a determined duration), and by that, you will see imaginary parallel execution of different instructions in different threads. Maybe one second long instruction set will be executed in a one short lived thread while another long running thread (especially main thread) keeps running and by that short living thread will not wait the long running thread to be finished. That is the magical part of multi threaded executions.
@@mils3318 Yes, it is possible to run multiple threads in parallel within a single process in most modern operating systems. A process can have multiple threads of execution, which are also known as lightweight processes. Each thread runs concurrently and shares the process's resources, including memory and open files.
bro, we hate to read so that's why watching video but bro is writing essay here🤣🤣
@@TheZhouh12 so it is possible that, for example, if we have a 8-core CPU on it, in one currently active process, multiple threads can be executed in parallel... not multitasking.
Okay, thank you very much.
@@mils3318 When a CPU has multiple cores, it can execute multiple threads concurrently, as long as the operating system supports it. This is known as parallel processing.
@@mils3318 On a system with a single-core CPU, the operating system can still create multiple threads and schedule them to be executed one after the other, but they will not be able to run concurrently. This is known as multitasking.
I have to admit... I have never seen such good explaination videos merged with animations and diagrams in my life. GREAT CONTENT SIR! Keep on doing what you do.
Fantastic video - concise and clear explanations accompanied by extremely helpful visuals. Couldn't ask for a better description within 4 minutes of time. Subscribed!
All information that I knew but would be hard-pressed to scoop out of my brain on demand - it's great to have clear and succinct refreshers like this to keep the neurons fresh
Great channel. Simple, short and straight-forward
I really love these videos!!! The visuals are very helpful to build mental models and understand these complex concepts - thank you so much!!!
Recently came across your channel. Love the content. Very informative yet short enough to digest unlike most other tech videos
Analogy for understanding process and thread
• In essence a program/process/thread is executing a job(a set of instructions). So, in that context, it’s no different than physical labour work where one executes a bunch of instructions from his/her brain and uses the required tools to complete a job
• Imagine you hire a fitter to mount your newly bought TV and you have already bought a TV mount. Here, the fitter represents a program. He has skills required to mount the TV(Set of instructions) and required tools(Data, library, plugins)
• Hiring a fitter is equivalent to installing a program. You have got commitment from him/her to work on your job. And he brings himself and loads the tools in your space ready to do the job. But, You have yet to extract the job from him. For this, you need to prepare some physical space near your TV and also give him the authorization to work at your home. This is the equivalent of creating a process where you allocate CPU and ram memory for the program to execute its job
• Just as a program can spin up multiple process, a fitter can bring multiple fitters to execute the same job. All of them work independently in their own physical space and with required authorization
• So, what's the analogy for threads? A fitter usually breaks the job into sub tasks. Here, mounting a TV can be broken in tasks like punching holes in the wall, preparing the Mount frame, adjusting the tilt etc. These subtasks represent individual threads. These threads are executed in the same memory/heap space just as the fitter performs his subtasks on his original physical space.
•Threads can be executed in parallel saving time. You can imagine this to be fitter performing tasks at the same time using his two hands. For example, one hand used to punch holes in the wall and other hand used to prepare the mount frame. This might sound like a stretch but there are some crazy people who could multitask with both hands
Holy cow... so clear. So coherent. So neat. The graphics go perfectly with your explanation. Thank you for this.
1:00 "one process cannot corrupt the memory space of another process" - well, should not be able to.
I keep getting confused between the two (threads and processes) but this depiction has helped me a ton. Thank you!
Good refresher for me. Thanks once again for the awesome and meaningful video.
Thanks for those visuals, I can tell a lot of love went into them
Also, would love to see videos on "heap" and "serialization / encoding" (some visuals on why in-memory representation is different from byte sequence would be super super helpful ). Thanks again for these great videos!!!!
The graphics and animations are so good!
(And the content of course 😄)
Thanks for sharing!
YOu have a great way of explaining things. Keep the good work! Can't wait you get into subjects like Docker and Kubernetes.
Thank you! Very clear and useful video content!
Nice and insightful capture of concepts that I were fuzzy on : thanks for putting this together
Learnt more in 4 min than from 4 hrs of classes, thank you!
powerful concepts within just 4 minutes. Thanks
The best explanation I watched!
The standard here is exceptional. Thank you so much for this - I wish my lecturers had taken a leaf out of your book!
love it, short and on point. Also i like your style! directly subbed :)
Best video on this subject by far
Many many thanks! This is a great video instruction!
gosh, this is so clear and informative
Excellent Stuff!
Thanks for the great video!🎉
Multi tasking and multi threading needs to be well known and especially where to use under what circumstances 🙏
As always, incredible video! Real great work. I'm so impressed by the animations. How do you create them?
great explanation!
thank you for the information, sr. Subscribed!!!!
This video helped me, thank you 😊
very good. makes more sense now.
Well explained. Thank you.
Amazing SIR!
This is a brilliant video.
Love you Sir, please keep it up. and Thank you very much
We need more of these videos
Best explanation!!!
Thank you for this video! I got this question in an interview this week, and I wish I could have watched this video before the interview! So concise but detailed explanation! And now I get to know what is the purpose of "yield" in Python. None of the resources about it explain in context of OS and context switching...!
Brilliant channel
Great video. Thxs
simply awesome
Great Video
Please make more such videos on common interview questions explained so greatly
Hi, can the upcoming videos be on -> http polling (short and long), streaming, websockets etc. ? Thanks your teaching style is just awesome
Man you're dope, thanks a lot
clear concise explanation together with great graphics. Would love to know how you guys do your graphics.... Thank you...
This 4-minute video explains what my professor could not do in an entire semester.
This 4 minute video sums up your years of coding experience.
Sir Alex, Please do in-depth videos. The content you post is so amazing but they are covered on a high level. Please go deep and explain things.
Well done
Thanks for your sharing
Great video. But I didn't understand how auto yielding reduces the cost of context switching? Because after yielding, context switching will have to be done anyway for the CPU to execute other processes.
deserve a subscribe
animation is amazing
These animations are beautiful holy. Do you mind sharing just how they were accomplished?
If adding coroutine comparison, that would be perfect!
Code in a program, loaded into memory and executed by the processor, it becomes a process❤
You can add subtitles also for a larger audience
This is high quality content, but I'm also curious if you could do a video on how you make your videos? :)
Nice video! What about doing one about coroutines.
Good video
Thanks for great video. Two questions,
1. So to run K programs embarassingly parallel via multi-processing you have to have K CPU? If number of CPU < K then it would have to switch context, correct?
2. when we are talking about multi-processing python basically two of same script is copied to each process memory?
Love your channel. Subscribed to it.
If you don't mind, what tool do you use to author the content? I find this to be more engaging vs powerpoint based sessions.
Thanks
I'd be interested in hearing this too
@@thieltube390 Looks like Adobe After Effect
For the process having multiple threads, OS would provide time quantum of execution per thread under a process? or each thread would get (1 quantum time / no. of threads in process) time for execution?
pls upload more videos on operating systems concepts
A process is a program executing by a processor. A process doesn't share memory with another process. It has a collection of threads: the main thread and the other threads if any.
A thread is an execution unit inside a process. It shares the same heap memory with the other threads in the same process. But it has its own stack memory.
Captain 😅 it was precisely explained in the video
Can you please explain about fibres & co-routines?
It would be much more interesting to watch a video "fibers vs coroutines" :)
我的娘这么复杂🥲 amazing content tho! Thank you!
The simplest explanation I would say that the Process is virtualization of memory and Thread is virtualization of CPU the rest is following cons
What app did you use to create that animated presentation graphics?
And what if we have processors with more cores. Does this mean that we can run more processes at the same time? In that case, do we potentially have higher performance because more processors mean less context switching between processes?
Can we run two threads in parallel in one process? Or is only multitasking threads allowed per process (execution one by one)?
_And what if we have processors with more cores. Does this mean that we can run more processes at the same time?_
Yes, every logical core can run one thread.
_In that case, do we potentially have higher performance because more processors mean less context switching between processes?_
Hypothetically, if the number of active threads were lower than the number of available logical cores, no context switching would occur. However in reality, even freshly installed system like Windows 10 will have ~100-150 processes running by default, which means context switching is necessary.
Higher performance comes from being able to process multiple threads concurrently, not from reduced cost of context switching.
_Can we run two threads in parallel in one process?_
Yes, if code was properly written to allow multithreading.
超讚得
Do you feel like this same verbage is consistent when considering Erlang?
Describe fibers in react
program - executable instructions of code
Program disc + ram + cpu = process
process control block(PCB)
thread - unit of execution within process
stack
pointers
counters
thread vs process?
threads (of the same process) run in a shared memory space,
processes run in separate memory spaces
shared memory
virtual memory pages switching ⚠
fibers
coroutines
I am about to have an interview and this topic has given me a headache for days :(
What program is used for visualization?
what is the software used for animation
I like how he’s a fan of witcher 3
What software was this video made with?
I'm also interested in this question. Did you find it out?
@@kovolexiy nope a lot of channel not willing to share knowledge they scared of competition. What’s your telegram handler let’s research this up
@@kovolexiy Looks like Adobe After Effect
Does anyone know what animation software is used to create this video?
I was thinking of this for a long time. I'd also like to know. Not interested in the animation part. But the diagrams are beautiful
@@dgeo27 Looks like Adobe After Effect
Teaching them plz
Read the Windows internals book by Mark Russinovich and you guys will discover the new universe
can you or anybody from the comments provide a systematic overview of the relationship(technical,,,,not abstract concepts ///take x86, unix for example)bw mode bits(when exactly they are changed,,,,kindly try to be precise),kernel user mode(relating kernel stack ,,,ig both implementations ie per process,,,one for all)and virtual address spaces?
someone explain this to university level at the electron levels. like use logic gates, an electricity because in the end it is just 1's and 0's 1 instruction at a time
So how many process can 4 ram handle
Lets say for example
Chrome uses 2 processes : P1 and P2 each process has 2 threads t1.1, t1.2, t2.1 and t2.2
Firefox has 2 processes: P3 and P4
Each process has 4 threads
t3.1, t3.2, t3.3, t3.4, t4.1, t4.2, t4.3, t4.4
How the system will run them knowing that I have an 8 core cpu ?
They're not all executed at the same time. If you have more than 8 threads, the cores will interleave the execution between the threads and only one thread can make progress at a time using a core.
@@KrishnaKumar-yn9wf thanks but how.the system will prioritze them ? Will it run 8 from firefox ? (Suppose that there is no user interaction)
What about the virtual threads ans physical threads ?
@@brucewayne2480 do you know how does kubernetes manage the distribution of applications into the nodes ? There should be a gauger mechanism which may look at the resource consumption by the processes and other stuff by the OS. Such as kubernetes knows the whole nodes capacity and distributes new coming app installations into them. But I really do not know every detail.
The animation is too fast and too vibrant to catch details. With the monologue and constant changing animation, feels hard to catch up, harder to understand.
This should not be a fang interview question 💁
I think your animator is overdoing it, am having trouble focusing on the content. Also, could you pause and take breaks, because it feels like you're rushing. Thank you for the content though.
you want him to pause, instead of you pausing the video? 😂😂😂
Why is Heap inside Process? 0:58
The process owns the stack/heap.
In that drawing, there is code, data (bss/data/rodata), stack (main thread) and heap (memory to randomly allocate from)
@@adama7752I thought that all threads use the same heap. They store references (or pointers) in their corresponding stacks, but all of them reference to one Heap. Am I wrong?
We even need to synchronize threads if different threads access to the same data in Heap.