Build ruby with jemalloc

This should improve memory usage and test Ruby the way we do in
production.

scripts/install-ruby

@@ -7,9 +7,26 @@ set -xeou pipefail
 RUBY_VERSION=${1}
 RUBY_MAJOR=${1%.*} # strip last component
 RUBY_DOWNLOAD_SHA256=${2}
-
 RUBY_DOWNLOAD_URL="https://cache.ruby-lang.org/pub/ruby/${RUBY_MAJOR%-rc}/ruby-$RUBY_VERSION.tar.gz"
 
+JEMALLOC_VERSION=5.2.1
+JEMALLOC_DOWNLOAD_SHA256="34330e5ce276099e2e8950d9335db5a875689a4c6a56751ef3b1d8c537f887f6"
+JEMALLOC_DOWNLOAD_URL="https://github.com/jemalloc/jemalloc/releases/download/${JEMALLOC_VERSION}/jemalloc-${JEMALLOC_VERSION}.tar.bz2"
+
+# Download jemalloc
+mkdir -p /usr/src/jemalloc
+cd /usr/src/jemalloc
+curl --retry 6 -L -so jemalloc.tar.bz2 ${JEMALLOC_DOWNLOAD_URL}
+echo "${JEMALLOC_DOWNLOAD_SHA256} jemalloc.tar.bz2" | sha256sum -c -
+
+# Install jemalloc
+tar -xjf jemalloc.tar.bz2
+rm jemalloc.tar.bz2
+cd jemalloc-${JEMALLOC_VERSION}
+./autogen.sh --prefix=/usr --enable-prof
+make -j "$(nproc)" install
+cd /tmp
+
 # Download Ruby
 curl -fsSL "$RUBY_DOWNLOAD_URL" -o ruby.tar.gz
 echo "${RUBY_DOWNLOAD_SHA256} ruby.tar.gz" | sha256sum -c -
@@ -38,7 +55,7 @@ if [[ -d "/patches/ruby/$RUBY_VERSION" ]]; then
 fi
 
 # Compile
-./configure --enable-shared --disable-install-doc --disable-install-rdoc --disable-install-capi
+./configure --enable-shared --with-jemalloc --disable-install-doc --disable-install-rdoc --disable-install-capi
 make install -j $(nproc)
 
 # Cleanup