[glib: 1/2] gthread: Only print scheduler setting warnings once

[Sebastian Dröge <sdroege src gnome org>]

commit c8840ff9a8f8445e81ded935bb6637857089a99f
Author: Philip Withnall <withnall endlessm com>
Date:   Wed Sep 2 11:53:37 2020 +0100

    gthread: Only print scheduler setting warnings once
    
    If one thread pool thread fails to set its scheduler settings, it’s
    likely that all the rest of them will fail for the same reason. Avoid
    printing duplicate critical warnings in that case.
    
    Signed-off-by: Philip Withnall <withnall endlessm com>
    
    Fixes: #2191

 glib/gthread-posix.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/glib/gthread-posix.c b/glib/gthread-posix.c
index 29bc81a0f..f36055925 100644
--- a/glib/gthread-posix.c
+++ b/glib/gthread-posix.c
@@ -1235,6 +1235,7 @@ static void *
 linux_pthread_proxy (void *data)
 {
   GThreadPosix *thread = data;
+  static gboolean printed_scheduler_warning = FALSE;  /* (atomic) */
 
   /* Set scheduler settings first if requested */
   if (thread->scheduler_settings)
@@ -1247,8 +1248,11 @@ linux_pthread_proxy (void *data)
       tid = (pid_t) syscall (SYS_gettid);
       res = syscall (SYS_sched_setattr, tid, thread->scheduler_settings->attr, flags);
       errsv = errno;
-      if (res == -1)
+      if (res == -1 && g_atomic_int_compare_and_exchange (&printed_scheduler_warning, FALSE, TRUE))
         g_critical ("Failed to set scheduler settings: %s", g_strerror (errsv));
+      else if (res == -1)
+        g_debug ("Failed to set scheduler settings: %s", g_strerror (errsv));
+      printed_scheduler_warning = TRUE;
     }
 
   return thread->proxy (data);