msubprojects: Run action on all subprojects in parallel

This moves all the code into a class and call its run() method in a
thread. The class queues all logs to print them at the end to avoid
mixing output of multiple actions.

2 files changed, 10 insertions, 1 deletions

diff --git a/docs/markdown/Commands.md b/docs/markdown/Commands.md
index aa538b1..3f3cf9f 100644
--- a/docs/markdown/Commands.md
+++ b/docs/markdown/Commands.md
@@ -228,7 +228,9 @@ meson setup builddir
 
 {{ subprojects_usage.inc }}
 
-Manages subprojects of the Meson project.
+Manages subprojects of the Meson project. *Since 0.59.0* commands are run on
+multiple subprojects in parallel by default, use `--num-processes=1` if it is
+not desired.
 
 {{ subprojects_arguments.inc }}
 
diff --git a/docs/markdown/snippets/subprojects_command_parallel.md b/docs/markdown/snippets/subprojects_command_parallel.md
new file mode 100644
index 0000000..4d992e7
--- /dev/null
+++ b/docs/markdown/snippets/subprojects_command_parallel.md
@@ -0,0 +1,7 @@
+## Parallelized `meson subprojects` commands
+
+All `meson subprojects` commands are now run on each subproject in parallel by
+default. The number of processes can be controlled with `--num-processes`
+argument.
+
+This speeds up considerably IO-bound operations such as downloads and git fetch.