Install PHP 7.4 ZTS with ext-parallel on Debian 10

apt-get install build-essential pkg-config autoconf bison re2c libxml2-dev libssl-dev libsqlite3-dev libcurl4-openssl-dev libpng-dev libjpeg-dev libonig-dev libfreetype6-dev libxslt1-dev libzip-dev libtidy-dev libmysqlclient-dev

cd /usr/local/src

VERSION=7.4.21
wget -qO- https://www.php.net/distributions/php-${VERSION}.tar.gz | tar -xz
cd php-${VERSION}/ext


git clone --depth 1 --branch v1.1.4 https://github.com/krakjoe/parallel.git

cd ..
./buildconf --force

./configure \
    --prefix=/etc/php/7.4z \
    --with-config-file-path=/etc/php/7.4z \
    --with-config-file-scan-dir=/etc/php/7.4z/conf.d \
    --disable-cgi \
    --with-zlib \
    --with-zip \
    --enable-soap \
    --enable-intl \
    --with-openssl \
    --with-curl \
    --enable-mysqlnd \
    --with-mysqli=mysqlnd \
    --with-pdo-mysql=mysqlnd \
    --enable-pcntl \
    --enable-gd \
    --enable-exif \
    --with-jpeg \
    --with-freetype \
    --with-xsl \
    --with-gettext \
    --enable-bcmath \
    --enable-mbstring \
    --enable-calendar \
    --with-tidy \
    --enable-maintainer-zts \
    --enable-parallel \
    --enable-ftp \
    --enable-sockets

make -j$(nproc)
make install

cp php.ini-production /etc/php/7.4z/php.ini
ln -s /etc/php/7.4z/bin/php /usr/bin/php74z

Additional config: OPCache needs to be turned on, otherwise may run to memory corruption error in parallel extension.

mkdir /etc/php/7.4z/conf.d
nano /etc/php/7.4z/conf.d/additional.ini

memory_limit=-1

[opcache]
zend_extension=opcache
opcache.enable=1
opcache.enable_cli=1
opcache.memory_consumption=512
opcache.interned_strings_buffer=128

extension=amqp.so

pdo_mysql.default_socket="/var/run/mysqld/mysqld.sock"