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Jakub Kozłowski kubukoz

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View fibers.md

Fibers

Fibers are an abstraction over sequential computation, similar to threads but at a higher level. There are two ways to think about this model: by example, and abstractly from first principles. We'll start with the example.

(credit here is very much due to Fabio Labella, who's incredible Scala World talk describes these ideas far better than I can)

Callback Sequentialization

Consider the following three functions

View macos-catalina-nix.md

Since macOS Catalina, the root drive is read-only. The solution is to create a separate APFS volume and a “synthetic” /nix directory which points to it:

# Check if /nix exists, if not:
echo 'nix' | sudo tee -a /etc/synthetic.conf
# this will create a "synthetic" empty directory /nix

# REBOOT so macOS sees the synthetic directory

# After rebooting, create an APFS volume for Nix
View nix-remote-build.md

Okay, I've got a need to build Firefox from source, and I'd like to do that on a remote machine, and then copy build result back to my laptop. With Nix, using bastion host. I'll note details of my successful adventure.

Setup & Sources of knowledge

Here's the list of resources I've used actively:

Here's my setup:

@Daenyth
Daenyth / ByteStream.scala
Created Apr 8, 2019
ByteStream for fs2 - type-tagged byte encoding for Stream[F, Byte]
View ByteStream.scala
package teikametrics
import java.nio.charset.{Charset, StandardCharsets}
import akka.util.ByteString
import fs2.{Chunk, Pipe, RaiseThrowable, Stream}
import teikametrics.ByteEncoding._
/** Streamed bytes claiming to be encoded under `BE`
*
* @param chunkSize A chunk size to use for streaming operations, in order to use a consistent value and minimize array copying
View thread-pools.md

Thread Pools

Thread pools on the JVM should usually be divided into the following three categories:

  1. CPU-bound
  2. Blocking IO
  3. Non-blocking IO polling

Each of these categories has a different optimal configuration and usage pattern.

@paulp
paulp / global.sbt
Last active Oct 16, 2018
continuous compilation of the sbt build
View global.sbt
// These lines go in ~/.sbt/0.13/global.sbt
watchSources ++= (
(baseDirectory.value * "*.sbt").get
++ (baseDirectory.value / "project" * "*.scala").get
++ (baseDirectory.value / "project" * "*.sbt").get
)
addCommandAlias("rtu", "; reload ; test:update")
addCommandAlias("rtc", "; reload ; test:compile")
addCommandAlias("ru", "; reload ; update")
@jboner
jboner / latency.txt
Last active Jan 22, 2022
Latency Numbers Every Programmer Should Know
View latency.txt
Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference 0.5 ns
Branch mispredict 5 ns
L2 cache reference 7 ns 14x L1 cache
Mutex lock/unlock 25 ns
Main memory reference 100 ns 20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy 3,000 ns 3 us
Send 1K bytes over 1 Gbps network 10,000 ns 10 us
Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD