[FFmpeg-devel] [PATCH 2/2] tests/fate-run: add testing with a random number of threads

[Anton Khirnov]

Useful for discovering bugs that depend on a specific thread count.
Uses a simple PRNG copied from random() from libavutil/eval.c

Use like THREADS=randomX for a random thread count from 1 to X, with
X=16 when not specified.
---
 doc/fate.texi     | 5 +++++
 tests/fate-run.sh | 9 +++++++++
 2 files changed, 14 insertions(+)

diff --git a/doc/fate.texi b/doc/fate.texi
index 8450856015..13aea7a21f 100644
--- a/doc/fate.texi
+++ b/doc/fate.texi
@@ -223,6 +223,11 @@ meaning only while running the regression tests.
 Specify how many threads to use while running regression tests, it is
 quite useful to detect thread-related regressions.
 
+This variable may be set to the string "random", optionally followed by a
+number, like "random99", This will cause each test to use a random number of
+threads. If a number is specified, it is used as a maximum number of threads,
+otherwise 16 is the maximum.
+
 @item THREAD_TYPE
 Specify which threading strategy test, either @samp{slice} or @samp{frame},
 by default @samp{slice+frame}
diff --git a/tests/fate-run.sh b/tests/fate-run.sh
index e12279e4cf..55c579f84e 100755
--- a/tests/fate-run.sh
+++ b/tests/fate-run.sh
@@ -33,6 +33,15 @@ errfile="${outdir}/${test}.err"
 cmpfile="${outdir}/${test}.diff"
 repfile="${outdir}/${test}.rep"
 
+case $threads in
+    random*)
+        threads_max=${threads#random}
+        [ -z "$threads_max" ] && threads_max=16
+        threads="mod(time(0)*1664525+1013904223,$threads_max)+1"
+        ;;
+esac
+
+
 target_path(){
     test ${1} = ${1#/} && p=${target_path}/
     echo ${p}${1}
-- 
2.40.1