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In the talk "Clojure Concurrency" [1], Rich Hickey demands that everyone in the room read "Java Concurrency in Practice" [2]. "It will scare the crap out of you."

[1] https://youtu.be/dGVqrGmwOAw?t=23m57s [2] https://www.amazon.com/Java-Concurrency-Practice-Brian-Goetz...




Java 8 released march 2014. Youtube video published december 2012. Book originally published 2006. What am I missing?


The fact Java 8 streams only address a tiny sliver of the concurrency problems addressed by JCIP.

In practice, Java 8 parallel streams are generally discouraged outside of raw number crunching, which is rarely where we need parallel speedup anyway.


Ah ok. I was confused by the reponse to slaymaker1907 who recommended Streams directly, as it didn't seem to address the Stream API. I guess many of the challenges of concurrent computing still applies here.

When else do we need parallel speedup?


raw number crunching doesn't parallel speedup(!)?


Didn't say that, I said that we rarely need parallelization for raw number crunching. Developers use parallelization for coordinating expensive IO way more often, and Java 8 streams solve almost nothing for that. Still need to know and worry about other Java concurrency primitives like volatiles, monitors, thread pools, etc. and all their pitfalls (race conditions, deadlocks, etc.).

You should still read JCIP, it is still highly relevant in Java-land. Java 8 streams solved almost nothing in terms of concurrency (in fact they probably created more problems than they solved...). You should still be scared of concurrency in general, and particularly in Java. And you should definitely consider a different language with more sane and modern concurrency primitives if you really need concurrency.


The parent might be saying that we already have some good techniques for speeding up raw number crunching in parallel, so it's not as desirable to add yet another.


What do that comment mean?




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