Prevent slowdown in yum due to high file descriptor count

conda_smithy/templates/build_steps.sh.tmpl

@@ -21,6 +21,11 @@ export RECIPE_ROOT="${RECIPE_ROOT:-/home/conda/recipe_root}"
 export CI_SUPPORT="${FEEDSTOCK_ROOT}/.ci_support"
 export CONFIG_FILE="${CI_SUPPORT}/${CONFIG}.yaml"
 
+# Due to https://bugzilla.redhat.com/show_bug.cgi?id=1537564 old versions of rpm
+# are drastically slowed down when the number of file descriptors is very high.
+# This can be visible during a `yum install` step of a feedstock build.
+ulimit -n 1024
+
 cat >~/.condarc <<CONDARC
 
 conda-build:

news/1958_yum_fix_ulimit.rst

@@ -0,0 +1,26 @@
+**Added:**
+
+* <news item>
+
+**Changed:**
+
+* Changed the build_steps.sh template so that it sets the number of maximum file
+  descriptors to 1024. This is done to mitigate a bug in old rpm versions (such
+  as the one shipped with the Centos7 container) that cause the yum install step
+  to take tremendously longer than necessary.
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>