djspiewak

Quick Tips for Fast Code on the JVM

I was talking to a coworker recently about general techniques that almost always form the core of any effort to write very fast, down-to-the-metal hot path code on the JVM, and they pointed out that there really isn't a particularly good place to go for this information. It occurred to me that, really, I had more or less picked up all of it by word of mouth and experience, and there just aren't any good reference sources on the topic. So… here's my word of mouth.

This is by no means a comprehensive gist. It's also important to understand that the techniques that I outline in here are not 100% absolute either. Performance on the JVM is an incredibly complicated subject, and while there are rules that almost always hold true, the "almost" remains very salient. Also, for many or even most applications, there will be other techniques that I'm not mentioning which will have a greater impact. JMH, Java Flight Recorder, and a good profiler are your very best friend! Mea

cdleon

Works for macOS Sierra and High Sierra

Taken from 2011 Macbook Pro Graphics Card FIX 100% WORKING!!!

EDIT This method works! But there is an improved version for better thermal management and brightness keys functionality. See improved version -> https://gist.github.com/cdleon/d1eff7246a25193304284ecec40445b0

Enter Recovery Mode (text mode)

if you are on high sierra 10.13.6+ you might need to use Command + r instead

Boot up holding down Command + r + s

l15k4

import akka.Done
import akka.stream.ActorMaterializer
import akka.stream.alpakka.s3.MemoryBufferType
import akka.stream.alpakka.s3.scaladsl.S3Client
import akka.stream.scaladsl.{Flow, JsonFraming}
import com.typesafe.scalalogging.{LazyLogging, StrictLogging}
import org.backuity.clist.util.Read
import org.backuity.clist.{CliMain, arg, opt}
import org.joda.time.Interval
import org.joda.time.chrono.ISOChronology

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.

polvi

Easiest HDFS cluster in the world with kubernetes.

Inspiration from kimoonkim/kubernetes-HDFS

kubectl create -f namenode.yaml
kubectl create -f datanode.yaml

Setup a port-forward to so you can see it is alive:

rondy

FWIW: I (@rondy) am not the creator of the content shared here, which is an excerpt from Edmond Lau's book. I simply copied and pasted it from another location and saved it as a personal note, before it gained popularity on news.ycombinator.com. Unfortunately, I cannot recall the exact origin of the original source, nor was I able to find the author's name, so I am can't provide the appropriate credits.

---

Effective Engineer - Notes

• By Edmond Lau
• Highly Recommended 👍
• http://www.theeffectiveengineer.com/

What's an Effective Engineer?

t413

#!/usr/bin/env sh
## update.sh - manage a OpenWRT LetsEncrypt https instalation
# HOWTO: 
# - put update.sh in its own directory (like /root/.https)
# - run ./update.sh your.domain.com (that domain needs to point to your router)
#  * this get an issued cert from letsencrypt.org using the webroot verification method
#  * also installs curl and ca-certificates packages
# - use crontab -e; add the line `0 0 * * * "/root/.https/update.sh" >>/root/.https/log.txt 2>&`
#  * this runs the update every day, logging everything to log.txt
#

silasdavis

/**
* This file contains the core idea of wrapping an underlying OutputFormat with an OutputFormat
* with an augmented key that writes to partitions using MultipleOutputs (or something similar)
*/

package model.hadoop

import model.hadoop.HadoopIO.MultipleOutputer
import model.hadoop.HadoopIO.MultipleOutputer._
import org.apache.hadoop.io.{DataInputBuffer, NullWritable}

tswaters

This is way more complicated than it should be. The following conditions need to be met :

1. need to be able to track and merge in upstream changes
2. don't want remote commit messages in master
3. only interested in sub-directory of another repo
4. needs to go in a subdirectory in my repo.

In this particular case, I'm interested in bringing in the 'default' template of jsdoc as a sub-directory in my project so I could potentially make changes to the markup it genereates while also being able to update from upstream if there are changes. Ideally their template should be a separate repo added to jsdoc via a submodule -- this way I could fork it and things would be much easier.... but, it is what it is.

After much struggling with git, subtree and git-subtree, I ended up finding this http://archive.h2ik.co/2011/03/having-fun-with-git-subtree/ -- it basically sets up separate branches from tracking remote, the particular sub-directory, and uses git subtree contrib module to pull it all togther. Following are

xbeta

http://stackoverflow.com/questions/24380159/corebluetooth-and-wifi-interference

http://lists.apple.com/archives/bluetooth-dev/2013/Aug/msg00023.html

This is a well known issue, and it has a solution that is confirmed to work for the Mac side.

sudo defaults write /Library/Preferences/com.apple.airport.bt.plist bluetoothCoexMgmt Hybrid

After you run this script, the issue will go away and BT connections will remain stable.