[PATCH 01/12] check: improve test list randomization

Darrick J. Wong
2019-03-20T00:44:47Z

awk doesn't have a particularly good random number generator -- it seeds
from the Unix epoch time in seconds, which means that the run order
across a bunch of VMs started at exactly the same time are unsettlingly
predictable. Therefore, at least try to seed it with bash's $RANDOM,
which is slightly less predictable.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
check | 12 ++++++------
randomize.awk | 12 ++++++++----
2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/check b/check
index 20e95302..ecd1d39a 100755
--- a/check
+++ b/check
@@ -242,13 +242,13 @@ _prepare_test_list()
done

# sort the list of tests into numeric order
- list=`sort -n $tmp.list | uniq`
- rm -f $tmp.list
-
- if $randomize
- then
- list=`echo $list | awk -f randomize.awk`
+ if $randomize; then
+ sorter="awk -v seed=$RANDOM -f randomize.awk"
+ else
+ sorter="cat"
fi
+ list=`sort -n $tmp.list | uniq | $sorter`
+ rm -f $tmp.list
}

# Process command arguments first.
diff --git a/randomize.awk b/randomize.awk
index 0a8ad71a..d979fb03 100644
--- a/randomize.awk
+++ b/randomize.awk
@@ -15,10 +15,14 @@ function randomize(array, N) {
return
}

+BEGIN {
+ srand(seed)
+}
{
- srand()
- for (i = 0; i < NF; i++ ) array[i] = $(i+1)
- randomize(array, NF)
- for (i = 0; i < NF; i++) printf("%s ", array[i])
+ array[NR - 1] = $0
+}
+END {
+ randomize(array, NR)
+ for (i = 0; i < NR; i++) printf("%s ", array[i])
}