Use multiple threads on unit tests, but 16 at most

bind.spec

@@ -61,7 +61,7 @@ Summary:  The Berkeley Internet Name Domain (BIND) DNS (Domain Name System) serv
 Name:     bind
 License:  MPLv2.0
 Version:  9.18.5
-Release:  1%{?dist}
+Release:  2%{?dist}
 Epoch:    32
 Url:      https://www.isc.org/downloads/bind/
 #
@@ -449,11 +449,13 @@ export TSAN_OPTIONS="log_exe_name=true log_path=ThreadSanitizer exitcode=0"
 %if %{with UNITTEST}
   pushd build
   CPUS=$(lscpu -p=cpu,core | grep -v '^#' | wc -l)
+  THREADS="$CPUS"
   if [ "$CPUS" -gt 16 ]; then
     ORIGFILES=$(ulimit -n)
-    ulimit -n 4096 || : # Requires on some machines with many cores
+    THREADS=16
+    ulimit -n 8092 || : # Requires on some machines with many cores
   fi
-  make unit
+  make unit -j${THREADS}
   e=$?
   if [ "$e" -ne 0 ]; then
     echo "ERROR: this build of BIND failed 'make unit'. Aborting."
@@ -936,6 +938,9 @@ fi;
 %endif
 
 %changelog
+* Thu Aug 04 2022 Petr Menšík <pemensik@redhat.com> - 32:9.18.5-2
+- Use multiple threads on unit tests, but 16 at most
+
 * Wed Aug 03 2022 Petr Menšík <pemensik@redhat.com> - 32:9.18.5-1
 - Update to 9.18.5 (#2109170)
 - Return doc symlink to main page