Enable jemalloc for alpine.

check-server-process-using-jemalloc.rb

# Check server process is using jemalloc
# ref. [Japanese] https://tech.studyplus.co.jp/entry/2019/09/09/094140
class AppController < ActionController::Base
  def show
    r = `strings /proc/#{Process.pid}/maps | grep jemalloc`
    render plain: "<h1>#{ENV['LD_PRELOAD'].presence || 'empty'}</h1><pre>#{r}</pre>"
  end
end

enable-jemalloc-for-alpine.md

Dockerfile

FROM ruby:2.7-alpine AS builder

RUN apk add build-base
RUN wget -O - https://github.com/jemalloc/jemalloc/releases/download/5.2.1/jemalloc-5.2.1.tar.bz2 | tar -xj && \
    cd jemalloc-5.2.1 && \
    ./configure && \
    make && \
    make install


FROM ruby:2.7-alpine

COPY --from=builder /usr/local/lib/libjemalloc.so.2 /usr/local/lib/
ENV LD_PRELOAD=/usr/local/lib/libjemalloc.so.2

Reference

• jemalloc/jemalloc#1443 (comment)