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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

@aparrish
aparrish / understanding-word-vectors.ipynb
Last active May 11, 2022
Understanding word vectors: A tutorial for "Reading and Writing Electronic Text," a class I teach at ITP. (Python 2.7) Code examples released under CC0 https://creativecommons.org/choose/zero/, other text released under CC BY 4.0 https://creativecommons.org/licenses/by/4.0/
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@aparrish
aparrish / spacy_intro.ipynb
Last active Apr 8, 2022
NLP Concepts with spaCy. Code examples released under CC0 https://creativecommons.org/choose/zero/, other text released under CC BY 4.0 https://creativecommons.org/licenses/by/4.0/
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@davisford
davisford / Setup MongoDB on localhost as Replica Set
Last active Apr 21, 2022
Setup MongoDB replica set on local host with only a single primary
View Setup MongoDB on localhost as Replica Set
Add the `replication` section to the mongod.conf file:
```
$cat /usr/local/etc/mongod.conf
systemLog:
destination: file
path: /usr/local/var/log/mongodb/mongo.log
logAppend: true
storage:
engine: mmapv1
View Effective_Engineer.md

FWIW: I'm not the author of the content presented here (which is an outline from Edmond Lau's book). I've just copy-pasted it from somewhere over the Internet, but I cannot remember what exactly the original source is. I was also not able to find the author's name, so I cannot give him/her the proper credits.


Effective Engineer - Notes

What's an Effective Engineer?

View Principles-of-Adult-Behavior.md

Principles of Adult Behavior

  1. Be patient. No matter what.
  2. Don’t badmouth: Assign responsibility, not blame. Say nothing of another you wouldn’t say to him.
  3. Never assume the motives of others are, to them, less noble than yours are to you.
  4. Expand your sense of the possible.
  5. Don’t trouble yourself with matters you truly cannot change.
  6. Expect no more of anyone than you can deliver yourself.
  7. Tolerate ambiguity.
  8. Laugh at yourself frequently.
@hfreire
hfreire / qemu_osx_rpi_raspbian_jessie.sh
Last active Mar 22, 2022
How to emulate a Raspberry Pi (Raspbian Jessie) on Mac OSX (El Capitan)
View qemu_osx_rpi_raspbian_jessie.sh
# Install QEMU OSX port with ARM support
sudo port install qemu +target_arm
export QEMU=$(which qemu-system-arm)
# Dowload kernel and export location
curl -OL \
https://github.com/dhruvvyas90/qemu-rpi-kernel/blob/master/kernel-qemu-4.1.7-jessie
export RPI_KERNEL=./kernel-qemu-4.1.7-jessie
# Download filesystem and export location
@m-ou-se
m-ou-se / clock.scad
Last active Dec 11, 2016
3D model for my whiteboard clock
View clock.scad
$fs=1;
$fa=1;
servo_l = 24;
servo_w = 13;
servo_h = 21;
bolt_hole_diameter = 4.5;
servo_axis_diameter = 4;
@rklaehn
rklaehn / Proxy.scala
Created Jan 31, 2015
Minimal akka http proxy
View Proxy.scala
package akkahttptest
import akka.actor.ActorSystem
import akka.http.Http
import akka.stream.FlowMaterializer
import akka.http.server._
import akka.http.marshalling.PredefinedToResponseMarshallers._
import akka.stream.scaladsl.{HeadSink, Source}
object Proxy extends App {