Re: [PATCH] Enable parallelism in git submodule update.
- From
- Stefan Zager <szager@google.com>
- Date
- Oct 30, 2012, 18:11 UTC
- Message-ID
- <CAHOQ7J-e=KBOsjoeTWsf1f+LNgaAxN974-FXNMeOy7B-FR0wyg@mail.gmail.com>
- In-Reply-To
- <5090168f.5e+7ZUFKdYL2Qnw7%szager@google.com>
This is a refresh of a conversation from a couple of months ago.
I didn't try to implement all the desired features (e.g., smart logic for passing a -j parameter to recursive submodule invocations), but I did address the one issue that Junio insisted on: the code makes a best effort to detect whether xargs supports parallel execution on the host platform, and if it doesn't, then it prints a warning and falls back to serial execution.
Stefan
On Tue, Oct 30, 2012 at 11:03 AM, <szager@google.com> wrote:
Show 115 quoted lines
> The --jobs parameter may be used to set the degree of per-submodule
> parallel execution.
>
> Signed-off-by: Stefan Zager <szager@google.com>
> ---
> Documentation/git-submodule.txt | 8 ++++++-
> git-submodule.sh | 40 ++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 46 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/git-submodule.txt b/Documentation/git-submodule.txt
> index b4683bb..cb23ba7 100644
> --- a/Documentation/git-submodule.txt
> +++ b/Documentation/git-submodule.txt
> @@ -14,7 +14,8 @@ SYNOPSIS
> 'git submodule' [--quiet] status [--cached] [--recursive] [--] [<path>...]
> 'git submodule' [--quiet] init [--] [<path>...]
> 'git submodule' [--quiet] update [--init] [-N|--no-fetch] [--rebase]
> - [--reference <repository>] [--merge] [--recursive] [--] [<path>...]
> + [--reference <repository>] [--merge] [--recursive]
> + [-j|--jobs [jobs]] [--] [<path>...]
> 'git submodule' [--quiet] summary [--cached|--files] [(-n|--summary-limit) <n>]
> [commit] [--] [<path>...]
> 'git submodule' [--quiet] foreach [--recursive] <command>
> @@ -146,6 +147,11 @@ If the submodule is not yet initialized, and you just want to use the
> setting as stored in .gitmodules, you can automatically initialize the
> submodule with the `--init` option.
> +
> +By default, each submodule is treated serially. You may specify a degree of
> +parallel execution with the --jobs flag. If a parameter is provided, it is
> +the maximum number of jobs to run in parallel; without a parameter, all jobs are
> +run in parallel.
> ++
> If `--recursive` is specified, this command will recurse into the
> registered submodules, and update any nested submodules within.
> +
> diff --git a/git-submodule.sh b/git-submodule.sh
> index ab6b110..60a5f96 100755
> --- a/git-submodule.sh
> +++ b/git-submodule.sh
> @@ -8,7 +8,7 @@ dashless=$(basename "$0" | sed -e 's/-/ /')
> USAGE="[--quiet] add [-b branch] [-f|--force] [--reference <repository>] [--] <repository> [<path>]
> or: $dashless [--quiet] status [--cached] [--recursive] [--] [<path>...]
> or: $dashless [--quiet] init [--] [<path>...]
> - or: $dashless [--quiet] update [--init] [-N|--no-fetch] [-f|--force] [--rebase] [--reference <repository>] [--merge] [--recursive] [--] [<path>...]
> + or: $dashless [--quiet] update [--init] [-N|--no-fetch] [-f|--force] [--rebase] [--reference <repository>] [--merge] [--recursive] [-j|--jobs [jobs]] [--] [<path>...]
> or: $dashless [--quiet] summary [--cached|--files] [--summary-limit <n>] [commit] [--] [<path>...]
> or: $dashless [--quiet] foreach [--recursive] <command>
> or: $dashless [--quiet] sync [--] [<path>...]"
> @@ -500,6 +500,7 @@ cmd_update()
> {
> # parse $args after "submodule ... update".
> orig_flags=
> + jobs="1"
> while test $# -ne 0
> do
> case "$1" in
> @@ -518,6 +519,20 @@ cmd_update()
> -r|--rebase)
> update="rebase"
> ;;
> + -j|--jobs)
> + case "$2" in
> + ''|-*)
> + jobs="0"
> + ;;
> + *)
> + jobs="$2"
> + shift
> + ;;
> + esac
> + # Don't preserve this arg.
> + shift
> + continue
> + ;;
> --reference)
> case "$2" in '') usage ;; esac
> reference="--reference=$2"
> @@ -551,11 +566,34 @@ cmd_update()
> shift
> done
>
> + # Correctly handle the case where '-q' came before 'update' on the command line.
> + if test -n "$GIT_QUIET"
> + then
> + orig_flags="$orig_flags -q"
> + fi
> +
> if test -n "$init"
> then
> cmd_init "--" "$@" || return
> fi
>
> + if test "$jobs" != 1
> + then
> + if ( echo test | xargs -P "$jobs" true 2>/dev/null )
> + then
> + if ( echo test | xargs --max-lines=1 true 2>/dev/null ); then
> + max_lines="--max-lines=1"
> + else
> + max_lines="-L 1"
> + fi
> + module_list "$@" | awk '{print $4}' |
> + xargs $max_lines -P "$jobs" git submodule update $orig_flags
> + return
> + else
> + echo "Warn: parallel execution is not supported on this platform."
> + fi
> + fi
> +
> cloned_modules=
> module_list "$@" | {
> err=
> --
> 1.7.7.3
>