We all are using RAM, probably DDR4 is just sitting there in your PC and serving memory with an outstanding speed, even while you are reading this sentence. But have you ever wondered how DRAM is working internally?

If so, please find my new poster about DRAM anatomy. It provides a little oversimplified view, for illustrative purposes. But it explains DRAM internals “good enough” for any regular, mortal developer like you and me. This is a great basis to understand while linear memory access is so much preferred over random one, cryptic mamory access timings like 8-8-8-24, and for explaining bugs like Rowhammer bug. Or just to hang it on the wall as a nerdy decoration 🙂

The poster is available for free in a printable version from

Here are some additional materials that you can follow while interpreting/digging in this poster:

Happy printing!


Testing shows the presence of errors in a product, but “cannot prove that there are no defects” – you probably know that quote. I remember so many hours spent on debugging those little, mean bugs hidding deeply in the code edge cases. But what’s worse, I remember even more hours trying to understand and reproduce an error that happens only in production environment. Here’s the first top 5 most popular issues I’ve met during last years:

  • app hangs due to deadlocks (in the app or external library)
  • memory issues like memory leaks, long GC pauses or high CPU usage due to the GC
  • swallowed exception preventing some logic, with no logs available
  • threading issues like thread-pool starvation
  • intermittent errors due to the resources shortage, like running out of sockets or file handles

BTW. And what’s yours top 5?

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