We sometimes erroneously detected processes in other sessions as belonging to our session. Conseque…

build/install-chroot.sh

 #!/bin/bash -e
 
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This script installs Debian-derived distributions in a chroot environment.
 # It can for example be used to have an accurate 32bit build and test
 # environment when otherwise working on a 64bit machine.
 # N. B. it is unlikely that this script will ever work on anything other than a
@@ skipping 480 matching lines @@
     --)             shift; break;;
     -h|--help)      shift; help;;
     -l|--list)      shift; list;;
     -c|--clean)     shift; clean "${chroot}";;
     -C|--clean-all) shift; clean;;
     *)              break;;
   esac
 done
 
 session="$(schroot -c "${chroot}" -b)"
+export CHROOT_SESSION_ID="${session}"
 
 if [ $# -eq 0 ]; then
   schroot -c "${session}" -r -p
 else
   p="$1"; shift
   schroot -c "${session}" -r -p "$p" -- "$@"
 fi
 rc=$?
 
 i=$(schroot -c "${session}" -r -p ls -- -id /proc/self/root/. |
      awk '{ print $1 }') 2>/dev/null
+other_pids=
 while [ -n "$i" ]; do
-  pids=$(ls -id1 /proc/*/root/. 2>/dev/null |
+  pids=$({ ls -id1 /proc/*/root/. 2>/dev/null |

[jln (very slow on Chromium), 2013/07/23 00:41:20]

Add a comment to explain the set substraction magic here ?

          sed -e 's,^[^0-9]*'$i'.*/\([1-9][0-9]*\)/.*$,\1,
                  t
-                 d') >/dev/null 2>&1
-  [ -z "$pids" ] && break
-  kill -9 $pids
+                 d';
+         echo "${other_pids}";
+         echo "${other_pids}"; } | sort | uniq -u) >/dev/null 2>&1
+  # Kill all processes that are still left running in the session. This is
+  # typically an assortment of daemon processes that were started
+  # automatically. They result in us being unable to tear down the session
+  # cleanly.
+  [ -z "${pids}" ] && break
+  for j in $pids; do
+    # Unfortunately, the way that schroot sets up sessions has the
+    # side-effect of being unable to tell one session apart from another.
+    # This can result in us attempting to kill processes in other sessions.
+    # We make a best-effort to avoid doing so.
+    k="$( ( xargs -0 -n1 </proc/$j/environ ) 2>/dev/null |
+         sed 's/^CHROOT_SESSION_ID=/x/;t1;d;:1;q')"
+    if [ -n "${k}" -a "${k#x}" != "${session}" ]; then
+      other_pids="${other_pids}
+${j}"
+      continue
+    fi
+    kill -9 $pids
+  done
 done
 schroot -c "${session}" -e
 exit $rc
 EOF
 sudo chown root:root /usr/local/bin/"${target%bit}"
 sudo chmod 755 /usr/local/bin/"${target%bit}"
 
 # Add the standard Ubuntu update repositories if requested.
 [ "${alt_repos}" = "y" -a \
   -r "/var/lib/chroot/${target}/etc/apt/sources.list" ] &&
@@ skipping 278 matching lines @@
 
 For Chrome, this probably means you want to make your "out" directory a
 symbolic link that points somewhere inside of "${HOME}/chroot".
 
 You still need to run "gclient runhooks" whenever you switch from building
 outside of the chroot to inside of the chroot. But you will find that you
 don't have to repeatedly erase and then completely rebuild all your object
 and binary files.
 
 EOF