Fixes for Overtone and SuperCollider on PopOS 20.10

02 November 2020

I took the update to PopOS 20.10, and my Overtone setup stopped working. When I’d try to boot up the internal SuperCollider server from Emacs or from the leiningen repl on my music projects which all (:require [ :refer :all]), get an error in native libraries. I could also try to start the server with (boot-internal-server) or (boot-external-server), but it gives the same error.

--> Booting internal SuperCollider server...
Cannot read socket fd = 107 err = Success
CheckRes error
Could not read result type = 22
Client name = Overtone conflits with another running client
Cannot connect to the server
JackShmReadWritePtr1::~JackShmReadWritePtr1 - Init not done for -1, skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
could not initialize audio.
# A fatal error has been detected by the Java Runtime Environment:
#  SIGSEGV (0xb) at pc=0x00007f5eec0e9ba7, pid=30517, tid=30605
# JRE version: OpenJDK Runtime Environment AdoptOpenJDK (15.0.1+9) (build 15.0.1+9)
# Java VM: OpenJDK 64-Bit Server VM AdoptOpenJDK (15.0.1+9, mixed mode, sharing, tiered, compressed oops, g1 gc, linux-amd64)
# Problematic frame:
# C  []  World_WaitForQuit+0x7
# No core dump will be written. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
# An error report file with more information is saved as:
# /home/john/workspace/music/hs_err_pid30517.log
--> Connecting to internal SuperCollider server...
[thread 30576 also had an error]
# If you would like to submit a bug report, please visit:
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.

Since it can no longer start the server internally from within Overtone, I start the server manually. I wrapped a script around the start up, so I can set the environment variables for configuring jack and starting up the synth:


# automatically connect up jack ports
export SC_JACK_DEFAULT_INPUTS="system:capture_1,system:capture_2"
export SC_JACK_DEFAULT_OUTPUTS="system:playback_1,system:playback_2"

scsynth -u 57110

To get Overtone going again, I disabled the automatic boot of the server within Overtone by switching all the requires in each file from to overtone.core, and I connect to that external server from my REPL manually with (connect-external-server) before doing anything else.

Finally, Overtone was consistently failing to find my MIDI keyboard. When things were working well enough a couple months ago, it still had required a little dance of killing off jackd and restarting Overtone, since something had been tying up the MIDI interface. This workaround was no longer adequate, since scsynth and jackd needed to already be started. I disabled MIDI connection in jackd by removing the -Xseq option from my ~/.jackdrc.

I’m back in business, and it’s probably more robust with these manual steps now. I think I’m also seeing some other odd little things working with the external server that didn’t previously, like using (mouse-x) for reading mouse positions into the synth values. The built-in piano synth is also working where it hadn’t previously.

Escape with Spacemacs in Tmux

21 October 2020

I’ve occasionally been using a SSH session from my Pixel phones for years to login to my servers and write Clojure code in Emacs. I’d often run into an issue where I find myself having a weird time switching between NORMAL and INSERT modes when I’d hit ESCAPE quickly and try to move the cursor.

Googling my random problems is a favorite pastime, and I’ve finally stumbled upon an article about tmux and vim escape key. I learned that it’s probably been tmux sporadically eating my ESCAPE key, so I’ve tried disabling the built-in delay by adding to my .tmux.conf:

set -g -s escape-time 0

Templates and Snippets in Emacs

30 August 2020

I was only trying to write that last article, but it took me days to finally do it. I had so much work to do before I got there.

I had come to appreciate Emacs automatically inserting the boilerplate namespace declarations in new Clojure files, and I really thought I needed such convenience for my blog posts written in AsciiDoc in JBake. I dove down a 20-tab-deep, yak-shaving hole to get it done. [1]

I had to figure out the right search terms and names for what Emacs was doing for me. I finally found yatemplate which seems similar to yasnippets. Spacemacs has the templates layer for integrating yatemplate support, so I added that layer and created a template for my adoc files in my .emacs.d directory. My simple case worked, but I recognized that I’ll want that template on all my machines, so having a local copy of it wouldn’t cut it. I needed a way to check-in and version more Emacs/Spacemacs files than just my ~/.spacemacs files I was previously distributing.

I learned yasnippets would default to looking in ~/.spacemacs.d/ if the configuration was in there, so I had to move my ~/.spacemacs file over to ~/.spacemacs.d/init.el. To have the templates layer source templates from the .spacemacs.d directory, it required an extra bit of configuration when introducing it to the dotspacemacs-configuration-layers:

  (templates :variables templates-private-directory "~/.spacemacs.d/templates")

At this point, I could now commit my .spacemacs.d directory with the regular configuration file and the supporting templates and snippets. All those files will be cloned to all my workstations.

I was almost ready to write that article, but yasnippet and yatemplate have this fancy templating language. I’m sure that can make my article-creation even smarter! I read a bit more and found a couple cool elisp functions for automatically filling in the date and building a title from the file name. With the final enhancements to my adoc template, I could write the article, if I could only remember what I was trying to do in the first place. I hope to at least remember how to use these snippets and templates for future work.

1. I often measure task complexity in the number of tabs I end up having opened.


18 September 2018

Months ago, I started setting up LetsEncrypt using certbot on my Debian web server. It hosts multiple virtual hosts, so I setup 2 different sets of certificates: one for and the other for

On Debian, at least when I got started, it was recommernded to have certbot shutdown your apache2 and let it start its own temporary web server to verify the LetsEncrypt setup (--authenticator standalone). The other trick is to register multiple domain names for one certificate by repeating the -d option. I did this with this invocation:

certbot \
    --pre-hook "systemctl stop apache2" \
    --post-hook "systemctl start apache2" \
    --authenticator standalone \
    --installer apache \
    -d \
    -d \

I got it started a couple months ago, but I didn’t know how to setup multiple domain names, so I was always getting errors that this certificate was for a different name: instead of, etc.

That’s all sorted out now, and all my sites should be SSL all the time.

For more information on setup, certbot has a great set of guides based on your OS and web server.

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