jjb

For years, people have been using jemalloc with ruby. There were various benchmarks and discussions. Legend had it that Jemalloc 5 didn't work as well as Jemalloc 3.

Then, one day, hope appeared on the horizon. @wjordan offered a config for Jemalloc 5.

Ubuntu/Debian

FROM ruby:3.1.2-bullseye
RUN apt-get update ; \

jjb

invoke with bin/jemalloc rails s

We weren’t using 3 before, but have been running 5 in prod for ~10 months now, we saw ~25% less memory usage compared to default malloc

see also https://gist.github.com/jjb/9ff0d3f622c8bbe904fe7a82e35152fc

jjb

1. hello
2. hello
   1. nested
   2. nested
      1. more
      2. more
         1. and again

            puts "hello"

jjb

• runner does not use executor in <7, does use it in >=7
• console does not use executor in <7, not sure about >=7

jjb

example program being monitored - sleep.sh

while [ 1 ]
do
  sleep 1
  echo hello
done

jjb

require 'socket'
Socket.tcp("example.com", 443, connect_timeout: 1).close

jjb

raw = Rails.cache.redis.get( Rails.cache.redis.keys.first)
Marshal.load raw
Marshal.load(raw).instance_variable_get :@value
Zlib::Inflate.inflate Marshal.load(raw).instance_variable_get :@value



Marshal.load Zlib::Inflate.inflate Marshal.load(raw).instance_variable_get :@value

jjb

sudo port unload postgresql12-server
sudo port load postgresql12-server

jjb

sudo -u postgres pg_ctl -D /opt/local/var/db/postgresql12/defaultdb stop
sudo -u postgres pg_ctl -D /opt/local/var/db/postgresql12/defaultdb start

jjb

Ruby doesn't let you inherit default behavior when writing a signal trap

Here's a beginning of an exploration of what default behavior is for each signal:

# https://github.com/ruby/ruby/blob/master/signal.c#L1331-L1358
reserved = %w[SEGV BUS ILL FPE VTALRM]
reserved += %w[KILL STOP] # not listed in code but reserved via some other mechanism i was too lazy to find

Signal.list.keys.each do |signal|