From 80627bfe8ff3a42161597bea24a257e78ff94b94 Mon Sep 17 00:00:00 2001 From: emilylange Date: Wed, 25 Oct 2023 23:56:55 +0200 Subject: [PATCH] stdenv: enable multithreading for `xz` decompression (only if the implementation supports it) This speeds up the decompression of huge tar.xz tarballs (e.g. chromium) on high core count systems. --- pkgs/stdenv/generic/setup.sh | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/pkgs/stdenv/generic/setup.sh b/pkgs/stdenv/generic/setup.sh index ad9857fc9d61..4a8e434745c1 100644 --- a/pkgs/stdenv/generic/setup.sh +++ b/pkgs/stdenv/generic/setup.sh @@ -1057,7 +1057,11 @@ _defaultUnpack() { case "$fn" in *.tar.xz | *.tar.lzma | *.txz) # Don't rely on tar knowing about .xz. - xz -d < "$fn" | tar xf - --warning=no-timestamp + # Additionally, we have multiple different xz binaries with different feature sets in different + # stages. The XZ_OPT env var is only used by the full "XZ utils" implementation, which supports + # the --threads (-T) flag. This allows us to enable multithreaded decompression exclusively on + # that implementation, without the use of complex bash conditionals and checks. + XZ_OPT="--threads=$NIX_BUILD_CORES" xz -d < "$fn" | tar xf - --warning=no-timestamp ;; *.tar | *.tar.* | *.tgz | *.tbz2 | *.tbz) # GNU tar can automatically select the decompression method