travis: print some statistics from "top".

.travis.yml

@@ -201,6 +201,7 @@ env:
     - secure: "cFh8thThqEJLC98XKI5pfqflUzOlxsYPRW20AWRaYOOgYHPTiGWypTXiPbGSKaeAXTZoOA+DpQtEmefc0U6lt9dHc7a/MIaK6isFurjlnKYiLOeTruzyu1z7PWCeZ/jKXsU2RK/88DBtlNwfMdaMIeuKj14IVfpepPPL71ETbuk="
 
 before_install:
+  # - ./src/ci/top.sh &
   - zcat $HOME/docker/rust-ci.tar.gz | docker load || true
   - mkdir -p $HOME/rustsrc
   # FIXME(#46924): these two commands are required to enable IPv6,
@@ -290,6 +291,8 @@ after_failure:
 # the failure was while updating it (as it may be in a bad state)
 # https://github.com/travis-ci/travis-ci/issues/4472
 before_cache:
+  # - echo "top statistics:"
+  # - cat /tmp/top.log
   - docker history -q rust-ci |
     grep -v missing |
     xargs docker save |

src/ci/top.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+# Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+# file at the top-level directory of this distribution and at
+# http://rust-lang.org/COPYRIGHT.
+#
+# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+# option. This file may not be copied, modified, or distributed
+# except according to those terms.
+
+while `sleep 30`
+do
+# get tops summary and print it into a logfile every 30 secs
+# run top in batch mode (b), skip idle processes (i) and quite after first output (n 1)
+top -ibn 1 | head -n4 | tr "\n" " " | tee -a /tmp/top.log
+echo "" | tee -a /tmp/top.log
+done