processes: Fix 'delay_rate' race condition

When ts_delay_by_tgid() failed (for example, when observable process
terminates), `ps->delay` fields are not updated and remain set to zero.

This interpreted as counter overflow and produces spike.

Issue: #3026

diff --git a/src/processes.c b/src/processes.c
index ce4cc65..171dde9 100644 (file)
--- a/src/processes.c
+++ b/src/processes.c
@@ -587,7 +587,8 @@ static void ps_list_add(const char *name, const char *cmdline,
                       entry->cpu_system_counter);
 
 #if HAVE_LIBTASKSTATS
                       entry->cpu_system_counter);
 
 #if HAVE_LIBTASKSTATS

-    ps_update_delay(ps, pse, entry);
+    if (entry->has_delay)
+      ps_update_delay(ps, pse, entry);

 #endif
   }
 }
 #endif
   }
 }