[FFmpeg-cvslog] slicethread: Limit the automatic number of threads to 16

[Martin Storsjö]

ffmpeg | branch: master | Martin Storsjö <martin at martin.st> | Mon Sep  5 15:17:56 2022 +0300| [da5f7799a03aa53d0ffd25572aa9c65ba8279e57] | committer: Martin Storsjö

slicethread: Limit the automatic number of threads to 16

This matches a similar cap on the number of automatic threads
in libavcodec/pthread_slice.c.

On systems with lots of cores, this fixes a couple fate failures
in 32 bit mode on such machines (where spawning a huge number of
threads runs out of address space).

Signed-off-by: Martin Storsjö <martin at martin.st>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=da5f7799a03aa53d0ffd25572aa9c65ba8279e57
---

 libavutil/slicethread.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libavutil/slicethread.c b/libavutil/slicethread.c
index ea1c9c8311..115b099736 100644
--- a/libavutil/slicethread.c
+++ b/libavutil/slicethread.c
@@ -24,6 +24,8 @@
 #include "thread.h"
 #include "avassert.h"
 
+#define MAX_AUTO_THREADS 16
+
 #if HAVE_PTHREADS || HAVE_W32THREADS || HAVE_OS2THREADS
 
 typedef struct WorkerContext {
@@ -105,7 +107,7 @@ int avpriv_slicethread_create(AVSliceThread **pctx, void *priv,
     if (!nb_threads) {
         int nb_cpus = av_cpu_count();
         if (nb_cpus > 1)
-            nb_threads = nb_cpus + 1;
+            nb_threads = FFMIN(nb_cpus + 1, MAX_AUTO_THREADS);
         else
             nb_threads = 1;
     }