jjb

This is a very quick gist I'm throwing together to get this info and discussion onto google in one place.

For years, people have been using jemalloc with ruby. There are various benchmarks and discussions. Some people say Jemalloc 5 doesn't work as well as Jemalloc 3.

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

The recipe would be something like this (shown with official docker ruby image). I didn't try this yet, don't know if it will build!

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|