Bug#1092641: debootstrap: Can the last 'sync' call be removed?

[Roland Clobus]

Package: debootstrap
Version: 1.0.140
Severity: wishlist
Tags: patch

Hello maintainers of debootstrap,

Would it be possible to remove the explicit call to 'sync' in '/usr/sbin/debootstrap'? This is related to, but not identical to the issue in https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=700633.

To reproduce:
* Have 2 shells open


Test scenarios:
* copy is running -> debootstrap is slow
* copy is finished -> debootstrap is fast
* copy is running -> 'eatmydata debootstrap' is fast


The fast times are all nearly identical

* In shell 1: copy a large file on mount point A (I copied a 16GB file) (this generates some real I/O on the system) * In shell 2: rm -fr ./sid-chroot;time debootstrap sid ./sid-chroot > /dev/null (while the copy in the other shell is in progress) (I used /dev/shm) * copy is running, the 'sync' from /usr/sbin/debootstrap is commented out -> debootstrap is fast This leads me to think that the call to 'sync' in https://salsa.debian.org/installer-team/debootstrap/-/blob/master/debootstrap?ref_type=heads#L869= is not required.

https://salsa.debian.org/installer-team/debootstrap/-/commit/f45e6190c00065a7ad362fef955ec62b7ebf43a0

With kind regards,
Roland Clobus



-- System Information:
Debian Release: trixie/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'testing-debug'), (50, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 6.12.6-amd64 (SMP w/8 CPU threads; PREEMPT)

Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages debootstrap depends on:
ii  distro-info  1.12
ii  wget         1.24.5-2+b1

Versions of packages debootstrap recommends:
ii  arch-test               0.21-1.1
ii  debian-archive-keyring  2023.4
ii  gpgv                    2.2.45-2
ii  mount                   2.40.2-13
ii  sqv                     1.2.1-5

Versions of packages debootstrap suggests:
ii  binutils                2.43.50.20241230-1
pn  squid-deb-proxy-client  <none>
pn  ubuntu-archive-keyring  <none>
ii  xz-utils                5.6.3-1+b1
ii  zstd                    1.5.6+dfsg-2

-- no debconf information

The call to 'sync' was in the initial commit from 2007-06-16 and (apart from cosmetic changes) not changed since then. PS: I am also happy with wrapping the invocation of debootstrap with eatmydata for my specific use case Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE=en_GB:en

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