CI: Limit maximum number of test processes to 32

There are spurious failures happening in CI runs and I blame those on
too many processes running at the same time overloading either the
compositor we're running against, or causing OOM situations or just
genereally slowing things down and hitting timeout limits.

The choice of 32 is rather arbitrary. I just picked a number that felt
good.

.gitlab-ci.yml

@@ -26,6 +26,7 @@ variables:
   BACKEND_FLAGS: "-Dx11-backend=true -Dwayland-backend=true -Dbroadway-backend=true"
   FEATURE_FLAGS: "-Dvulkan=enabled -Dcloudproviders=enabled -Dbuild-testsuite=true -Dintrospection=enabled"
   MESON_TEST_TIMEOUT_MULTIPLIER: 3
+  MESON_TEST_MAX_PROCESSES: 32
   FEDORA_IMAGE: "registry.gitlab.gnome.org/gnome/gtk/fedora:v52"
 
 workflow:

.gitlab-ci/run-tests.sh

@@ -8,6 +8,7 @@ builddir=$1
 setup=$2
 suite=$3
 multiplier=${MESON_TEST_TIMEOUT_MULTIPLIER:-1}
+n_processes=${MESON_TEST_MAX_PROCESSES:-1}
 
 # Ignore memory leaks lower in dependencies
 export LSAN_OPTIONS=suppressions=$srcdir/lsan.supp:print_suppressions=0:detect_leaks=0:allocator_may_return_null=1
@@ -18,6 +19,7 @@ case "${setup}" in
           meson test -C ${builddir} \
                 --quiet \
                 --timeout-multiplier "${multiplier}" \
+                --num-processes "${n_processes}" \
                 --print-errorlogs \
                 --setup=${setup} \
                 --suite=${suite//,/ --suite=} \
@@ -42,6 +44,7 @@ case "${setup}" in
     meson test -C ${builddir} \
                 --quiet \
                 --timeout-multiplier "${multiplier}" \
+                --num-processes "${n_processes}" \
                 --print-errorlogs \
                 --setup=${setup} \
                 --suite=${suite//,/ --suite=} \
@@ -65,6 +68,7 @@ case "${setup}" in
     meson test -C ${builddir} \
                 --quiet \
                 --timeout-multiplier "${multiplier}" \
+                --num-processes "${n_processes}" \
                 --print-errorlogs \
                 --setup=${setup} \
                 --suite=${suite//,/ --suite=} \