tests: use append mode to capture parallel make output

This will allow us to run the Automake testsuite forcing all the make
invocations in the test cases to run in parallel mode [1], but without
hitting the spurious failure reported in automake bug#11413.

See also:
<http://lists.gnu.org/archive/html/bug-make/2013-05/msg00135.html>

The make invocations in the test cases can be forced to run in parallel
mode by, e.g., invoking "make check" like this:

      make check AM_TESTSUITE_MAKE="make -j16"

The possible spurious failures hinted above are due to the fact that
the redirected output of parallel make can racily lose lines.  For
example, if GNU make (3.82) is run with -j10 on a Makefile like this:

    all = 0 1 2 3 4 5 6 7 8 9
    default: $(all)
    $(all):
            @sleep 0.$$(($RANDOM % 10)); echo $@

and has its standard output redirected in overwrite-mode to a regular
file, it looses a line of that output every 15 runs or so on a Fedora
17 system with 64 ppc64 cores.  Redirection in append mode does not
suffer of this problem, as explained here:
<http://lists.gnu.org/archive/html/automake-patches/2009-03/msg00073.html>

See also previous commits v1.12-63-g45c1fcd of 2012-05-05 (tests: use
append mode to capture parallel make output) and Release-1-10-280-g6426999
of 2009-03-10 (Use append mode to capture parallel test output).

* t/ax/am-test-lib.sh (run_make): Adjust and enhance.
* t/lisp8.sh: Take advantage of the enhancement, nd stop doing output
redirection for $MAKE by hand.
* t/tap-more.sh: Likewise.
* t/parallel-tests-concurrency.sh: Likewise.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>

1 files changed, 41 insertions, 14 deletions

diff --git a/t/ax/am-test-lib.sh b/t/ax/am-test-lib.sh
index 8072ce0d1..7aed3ee1a 100644
--- a/t/ax/am-test-lib.sh
+++ b/t/ax/am-test-lib.sh
@@ -184,7 +184,9 @@ is_valid_varname ()
 #
 run_make ()
 {
-  am__make_redirect=
+  am__make_redirect_stdout=no
+  am__make_redirect_stderr=no
+  am__make_redirect_stdall=no
   am__make_flags=
   # Follow-up code might want to analyse these, so don't make them as
   # private, nor unset them later.
@@ -194,15 +196,16 @@ run_make ()
   while test $# -gt 0; do
     case $1 in
       -e) am_make_rc_exp=$2; shift;;
-      -O) am__make_redirect="$am__make_redirect >stdout";;
-      -E) am__make_redirect="$am__make_redirect 2>stderr";;
-      -M) am__make_redirect=">output 2>&1";;
+      -O) am__make_redirect_stdout=yes;;
+      -E) am__make_redirect_stderr=yes;;
+      -M) am__make_redirect_stdall=yes;;
       --) shift; break;;
        *) break;;
     esac
     shift
   done
 
+  # Use append mode here to avoid dropping output.  See automake bug#11413
   if using_gmake; then
     # We can trust GNU make to correctly pass macro definitions given
     # on the command line down to sub-make invocations, and this allow
@@ -247,16 +250,41 @@ run_make ()
      unset am__make_flags
   fi
 
-  eval "\$MAKE${am__make_redirect}"' ${1+"$@"}' || am_make_rc_got=$?
+  # In redirecting make output below, use append mode, to avoid
+  # dropping output.  See automake bug#11413 for details.
+  # The exit status of 253 is a more-or-less random choice, to
+  # help us catch possible errors in redirections and error out
+  # accordingly.
+  (
+    : exec $MAKE ${1+"$@"} # Display traces for future command.
+    set +x # We need to remove them now, not to pollute redirected stderr.
+    if test $am__make_redirect_stdall = yes; then
+      : > output && exec 1>>output 2>&1 || exit 253
+    else
+      if test $am__make_redirect_stdout = yes; then
+        : > stdout && exec 1>>stdout || exit 253
+      fi
+      if test $am__make_redirect_stderr = yes; then
+        : > stderr && exec 2>>stderr || exit 253
+      fi
+    fi
+    exec $MAKE ${1+"$@"}
+  ) || am_make_rc_got=$?
 
-  case $am__make_redirect in
-           *output*) cat output;;
-    *stderr*stdout*) cat stdout && cat stderr >&2;;
-    *stdout*stderr*) cat stdout && cat stderr >&2;;
-           *stdout*) cat stdout;;
-           *stderr*) cat stderr >&2;;
-  esac \
-    || fatal_ "displaying make output"
+  if test $am_make_rc_got -eq 253; then
+    fatal_ "run_make: problems in redirecting make output"
+  fi
+
+  if test $am__make_redirect_stdall = yes; then
+    cat output || fatal_ "displaying make output"
+  else
+    if test $am__make_redirect_stdout = yes; then
+      cat stdout || fatal_ "displaying make output"
+    fi
+    if test $am__make_redirect_stderr = yes; then
+      cat stderr >&2 || fatal_ "displaying make output"
+    fi
+  fi
 
   case $am_make_rc_exp in
     IGNORE)
@@ -271,7 +299,6 @@ run_make ()
      test $am_make_rc_exp -eq $am_make_rc_got || return 1
      ;;
   esac
-  unset am__make_redirect
 }
 
 # AUTOMAKE_run [-e STATUS] [-d DESCRIPTION] [--] [AUTOMAKE-ARGS...]