Greg Dorrell Grogs

Why you prefer cats instead of zio? TF? It’s looks like zio ecosystem more widely and zio 2.0 has better performance What do you think?

Great question!

Performance-wise, it really depends on what you're doing. The problem with benchmarks (including the ones posted for ZIO and Cats Effect) is that they apply only to abstract situations, which are often nothing like what you see in real applications. A great write-up on this problem by Daniel Spiewak here, he wrote it better than I ever could: https://gist.github.com/djspiewak/f4cfc08e0827088f17032e0e9099d292

Also, this is not an app meant for production - I don't care that much about performance under load because there will be no load. And individual operations will often be bounded by I/O anyway, so the efficiency of the underlying runtime is likely not going to make a noticeable difference in use. Then again, both the client and server are JVM apps, so even the start-up penalty of the client will slow us down than picking even the least efficient e

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

Prerequisites : the letsencrypt CLI tool

This method allows your to generate and renew your Lets Encrypt certificates with 1 command. This is easily automatable to renew each 60 days, as advised.

You need nginx to answer on port 80 on all the domains you want a certificate for. Then you need to serve the challenge used by letsencrypt on /.well-known/acme-challenge. Then we invoke the letsencrypt command, telling the tool to write the challenge files in the directory we used as a root in the nginx configuration.

I redirect all HTTP requests on HTTPS, so my nginx config looks like :

server {

Let's say you have a Bash shell script, and you need to run a series of operations on another system (such as via ssh). There are a couple of ways to do this.

First, you can stage a child script on the remote system, then call it, passing along appropriate parameters. The problem with this is you will need to manually keep the remote script updated whenever you change it -- could be a bit of a challenge when you have something to execute on a number of remote servers (i.e., you have a backup script running on a central host, and it needs to put remote databases in hot backup mode before backing them up).

Another option is to embed the commands you want to run remotely within the ssh command line. But then you run into issues with escaping special characters, quoting, etc. This is ok if you only have a couple commands to run, but if it is a complex piece of Bash code, it can get a bit unwieldy.

So, to solve this, you can use a technique called rpcsh -- rpc in shell script, as follows:

First, place th

	/**
	* Original source:
	* [[https://gist.github.com/oxbowlakes/970717]]
	*
	* Modifications:
	* - use scala 7.0.5
	* - use toValidationNel
	* - use sequenceU and traverseU instead of the lambda trick
	*
	* Part Zero : 10:15 Saturday Night

	def urlses(cl: ClassLoader): Array[java.net.URL] = cl match {
	case null => Array()
	case u: java.net.URLClassLoader => u.getURLs() ++ urlses(cl.getParent)
	case _ => urlses(cl.getParent)
	}

	val urls = urlses(getClass.getClassLoader)
	println(urls.filterNot(_.toString.contains("ivy")).mkString("\n")

	#!/bin/sh

	# Quick start-stop-daemon example, derived from Debian /etc/init.d/ssh
	set -e

	# Must be a valid filename
	NAME=foo
	PIDFILE=/var/run/$NAME.pid
	#This is the command to be run, give the full pathname
	DAEMON=/usr/local/bin/bar

	#!/bin/sh

	echo "What should the Application be called (no spaces allowed e.g. GCal)?"
	read inputline
	name="$inputline"

	echo "What is the url (e.g. https://www.google.com/calendar/render)?"
	read inputline
	url="$inputline"