Concurrency & ParallelismTwo words used interchangeably that mean different things.ComputingConcurrency is dealing with many things at once.Parallelism is doing many things at once.Concurrent ≠ parallel · parallel implies concurrentOne core, ten tasks interleavedConcurrent, not parallelAsync I/O on a single thread.Four cores, four computationsParallelGenuinely simultaneous.Waiting on a network callConcurrency helps; parallelism does notThe CPU is idle either way.THE COMMON MISTAKEAdding threads to speed up I/O-bound workUse async, or a small poolThe bottleneck is the network, not the CPU. More threads add contextswitching, not throughput.Ask what the bottleneck is. CPU-bound work wants parallelism;I/O-bound work wants concurrency.Concurrency & Parallelismlearnposters.com
Concurrency & Parallelism — printable computing wall chart from LearnPosters. Free vector PDF, US Letter and A4.

What’s on the Concurrency & Parallelism poster

The rule, 3 worked examples, and the mistake everyone makes.

Ask what the bottleneck is. CPU-bound work wants parallelism; I/O-bound work wants concurrency.

Questions about the Concurrency & Parallelism poster

What’s on the Concurrency & Parallelism poster?
The rule, 3 worked examples, and the mistake everyone makes. Concurrency is dealing with many things at once. Parallelism is doing many things at…; Concurrent ≠ parallel · parallel implies concurrent; One core, ten tasks interleaved = Concurrent, not parallel; Four cores, four computations = Parallel; Waiting on a network call = Concurrency helps; parallelism does not; Common mistake: Adding threads to speed up I/O-bound work → Use async, or a small pool. Ask what the bottleneck is. CPU-bound work wants parallelism; I/O-bound work wants concurrency.
Who is the Concurrency & Parallelism poster for?
Concurrency & Parallelism belongs to the Computing section rather than to a school year, because computing is not something one grade owns. Anyone learning systems can pin it up — a beginner, a student mid-course, or someone revising years later.
When should you use the Concurrency & Parallelism poster?
Concurrency is about structure. Parallelism is about execution. A wall chart earns its place by being glanceable from where the work is happening, so Concurrency & Parallelism belongs on the wall where that computing work actually happens, within glancing distance, rather than filed away.
What other posters go with Concurrency & Parallelism?
Caching, DNS and Garbage Collection sit alongside Concurrency & Parallelism in the Computing section. Printed together they make a wall rather than a single sheet, which is how a reference set actually gets used.CachingDNSGarbage Collection
Is the Concurrency & Parallelism poster free to download and print?
Yes. Concurrency & Parallelism downloads as a free PDF with no account, no email and no watermark, like everything else in the Computing section. Print as many copies as you like for a home, a classroom, a library or a tutoring group; reselling the file is the only thing the licence rules out.Read the licence
What size does the Concurrency & Parallelism poster print at?
Concurrency & Parallelism is a vector PDF laid out for US Letter, and prints on A4 with Fit to page — the same file, no separate download. Because every mark on it is drawn rather than photographed, it stays sharp enlarged to A3, A2 or A1 at a copy shop. Colour carries emphasis only, so a greyscale print of Concurrency & Parallelism loses nothing.Printing guide

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