Luet memory usage

Luet version:

luet version 0.32.5-gd5d21653d7313ff396c0511af402834c89974ee3 2022-06-07

CPU architecture, OS, and Version:

Linux zzz 6.8.0-45-generic #45-Ubuntu SMP PREEMPT_DYNAMIC Fri Aug 30 12:02:04 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

Describe the bug

Luet gets OOM-killed with 4GB Docker image on a machine with 8GB of free memory.

To Reproduce

Issue docker build -t foobar for Dockerfile that grows large in size:

FROM busybox AS build
RUN dd if=/dev/zero of=foobar bs=65536 count=65536
FROM scratch AS final
COPY --from=build foobar foobar

Try to unpack it with luet

luet util unpack  --local foobar unpacked -d

Expected behavior

Luet's memory usage doesn't significantly depend on image size

Logs

  DEBUG   (config.go:#204:github.com/mudler/luet/cmd/util.initContext)  System rootfs: /
  DEBUG   (config.go:#205:github.com/mudler/luet/cmd/util.initContext)  Colors true
  DEBUG   (config.go:#206:github.com/mudler/luet/cmd/util.initContext)  Logging level info
  DEBUG   (config.go:#207:github.com/mudler/luet/cmd/util.initContext)  Debug mode true
 INFO   Downloading foobar to /home/lauri/unpacked
Killed

Additional context

Tried --concurrency=1 but still looks like 14 threads are spawned