[bcoates]

A thread is just a process that shares memory; a container is just a process that has a different network/filesystem/etc than the rest of the processes.

Containers don't cost meaningfully more than threads unless you create expensive unique resources for each one.

[CaveTech]

Network/Filesystem/Memory are not expensive resources? It's a lot of overhead. If you're going to claim that you can share memory between containers than arguably you don't have multiple containers but rather a single one.

This is way more overhead than threads which can share all of those resources.

[bcoates]

Network namespaces, virtual ethernet interfaces, iptables rules, & union filesystems are all very cheap and have little to no overhead for normal use cases. N processes in 1 container isn't a perf win over N processes in N containers.

Shared process memory isn't the easy memory-consumption win it sounds like, locking is hard to get right, potentially very destructive to the parallel performance that was the point of the whole exercise, and marries you to a single physical box.

Even if you want to take advantage of shared-address-space shared memory you probably want to do it in a more principled way than fork()

One-copy-per-thread and share-by-communicating both give you braindead simple scaling without dealing with that.