lukejones

For those who get issues with input lag on their bluetooth devices, do the following to remove the lag.

1. Open up Terminal.app (Applications > Utilities > Terminal)
2. Run the command sudo pkill bluetoothd (just copy and paste that into Terminal).
3. Hit Return/Enter.
4. Enter your macOS user password (the one you sign in to your Mac with).
5. Hit Return/Enter.
6. Wait for a few moments while the Bluetooth receiver resets and all the devices restart.

---

djspiewak

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.

galan

#!/bin/bash -e
# JAVA_HOME can be passed as argument if not set
if [ ! -d $JAVA_HOME ]; then
	JAVA_HOME=${1}
fi

KEYSTORE=$JAVA_HOME/jre/lib/security/cacerts
if [ ! -f "$KEYSTORE" ]; then
	echo "Keystore not found in '$KEYSTORE'"
	exit 1

djspiewak

Explaining Miles's Magic

Miles Sabin recently opened a pull request fixing the infamous SI-2712. First off, this is remarkable and, if merged, will make everyone's life enormously easier. This is a bug that a lot of people hit often without even realizing it, and they just assume that either they did something wrong or the compiler is broken in some weird way. It is especially common for users of scalaz or cats.

But that's not what I wanted to write about. What I want to write about is the exact semantics of Miles's fix, because it does impose some very specific assumptions about the way that type constructors work, and understanding those assumptions is the key to getting the most of it his fix.

For starters, here is the sort of thing that SI-2712 affects:

def foo[F[_], A](fa: F[A]): String = fa.toString

demisx

Provider	Singleton	Instantiable	Configurable
Constant	Yes	No	No
Value	Yes	No	No
Service	Yes	No	No
Factory	Yes	Yes	No
Decorator	Yes	No?	No
Provider	Yes	Yes	Yes

Constant

jboner

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