Parallel installation

Sometimes a need for network I/O parallelism, for performance efficiency, can be avoided. For example, repeated Alpine Linux-based container image builds can use a cache for /var/cache/apk across build runs. However, installing appears to happen sequentially. Since packages should not overlap on the filesystem, and their dependencies/integrity can be calculated, in principle, parallel installation must be possible. On the other hand, package installation parallelism may have interactions with a transactional or more specifically atomicity-related architecturally significant requirements.