# Concurrent Data Processing in Elixir: various errata

**URL:** <https://forum.devtalk.com/t/concurrent-data-processing-in-elixir-various-errata/6769>\
**Category:** PragProg Customers\
**Tags:** book-concurrent-data-processing-in-elixir, errata\
**Created:** [6 February 2021 13:43 UTC](https://forum.devtalk.com/t/concurrent-data-processing-in-elixir-various-errata/6769 "2021-02-06T13:43:27Z")\
**Posts on this page:** 1\
**Showing post:** 7

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**Author:** ![herminiotorres](https://forum.devtalk.com/user_avatar/forum.devtalk.com/herminiotorres/32/570_2.png) [@herminiotorres](https://forum.devtalk.com/u/herminiotorres)\
**Post date:** [18 February 2021 01:25 UTC](https://forum.devtalk.com/t/concurrent-data-processing-in-elixir-various-errata/6769/7 "2021-02-18T01:25:50Z")

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I like to share my thoughts about the book.

**Chapter 1:**  
I like your thoughts and perspective to use `Task` and `Task.Supervisor`, but maybe share how to create our own custom `Task.Supervisor`.

**Chapter 2:**  
I like the idea you use to create the `GenServer` and use it to improve the application to run `Task` on Chapter 1. It has good details about `GenServer` and the callbacks our module needs to implemented and introduce the last instructions about the `tuple` and the `spec` each callback receives as params. I feeling missing how to design the application supervisor tree, and how to think in perspective to guarantee our applications weren’t stop, maybe more content about `Registry` and how to use how to customize it and `Supervisor` and `DynamicSupervisor` too, the difference between both supervisors. The last thing is how to observe and debug, introducing this instrumentation when working with the `OTP.`

**Chapter 3:**  
I like the idea to drop into `GenStage` after the `GenServer` chapter because you are very fresh thoughts and very close to using these concepts for most GenServer applications. In this chapter, the knowledge about the supervisor tree is critical because you need to build how your entire stages need at least one process for each stage running. If some stage of my application it’s going down, the next or previous stage will fail. It could be more content about the `Dispatcher,` and I feel very quickly and small.

I like the application examples and how to use them to explain and conquer this knowledge about this abstract concept; sometimes it’s difficult to understand, a great book, and congrats. I’m very curious/excited about the next chapters and releases.

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