test-lib: support running tests under valgrind in parallel

With the new --valgrind-parallel=<n> option, we support running the
tests in a single test script under valgrind in parallel using 'n'
processes.

This really follows the dumbest approach possible, as follows:

* We spawn the test script 'n' times, using a throw-away
TEST_OUTPUT_DIRECTORY.  Each of the instances is given options that
ensures that it only runs every n-th test under valgrind, but
together they cover the entire range.

* We add up the numbers from the individual tests, and provide the
usual output.

This is really a gross hack at this point, and should be improved.  In
particular we should keep the actual outputs somewhere more easily
discoverable, and summarize them to the user.

Nevertheless, this is already workable and gives a speedup of more
than 2 on a dual-core (hyperthreaded) machine, using n=4.  This is
expected since the overhead of valgrind is so big (on the order of 20x
under good conditions, and a large startup overhead at every git
invocation) that redundantly running the non-valgrind tests in between
is not that expensive.

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Thomas Rast <trast@inf.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 8944e70e5cf6f3c483ff412b0fb68ab4d610c8ca..5b5ea6d386ef3ed8a1dc25cf777c02eecfd37109 100644 (file)
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -204,6 +204,15 @@ do
        --valgrind-only=*)
                valgrind_only=$(expr "z$1" : 'z[^=]*=\(.*\)')
                shift ;;
+       --valgrind-parallel=*)
+               valgrind_parallel=$(expr "z$1" : 'z[^=]*=\(.*\)')
+               shift ;;
+       --valgrind-only-stride=*)
+               valgrind_only_stride=$(expr "z$1" : 'z[^=]*=\(.*\)')
+               shift ;;
+       --valgrind-only-offset=*)
+               valgrind_only_offset=$(expr "z$1" : 'z[^=]*=\(.*\)')
+               shift ;;
        --tee)
                shift ;; # was handled already
        --root=*)
@@ -217,7 +226,7 @@ do
        esac
 done
 
-if test -n "$valgrind_only"
+if test -n "$valgrind_only" || test -n "$valgrind_only_stride"
 then
        test -z "$valgrind" && valgrind=memcheck
        test -z "$verbose" && verbose_only="$valgrind_only"
@@ -367,7 +376,9 @@ maybe_teardown_verbose () {
 last_verbose=t
 maybe_setup_verbose () {
        test -z "$verbose_only" && return
-       if match_pattern_list $test_count $verbose_only
+       if match_pattern_list $test_count $verbose_only ||
+               { test -n "$valgrind_only_stride" &&
+               expr $test_count "%" $valgrind_only_stride - $valgrind_only_offset = 0 >/dev/null; }
        then
                exec 4>&2 3>&1
                # Emit a delimiting blank line when going from
@@ -391,13 +402,17 @@ maybe_teardown_valgrind () {
 
 maybe_setup_valgrind () {
        test -z "$GIT_VALGRIND" && return
-       if test -z "$valgrind_only"
+       if test -z "$valgrind_only" && test -z "$valgrind_only_stride"
        then
                GIT_VALGRIND_ENABLED=t
                return
        fi
        GIT_VALGRIND_ENABLED=
        if match_pattern_list $test_count $valgrind_only
+       then
+               GIT_VALGRIND_ENABLED=t
+       elif test -n "$valgrind_only_stride" &&
+               expr $test_count "%" $valgrind_only_stride - $valgrind_only_offset = 0 >/dev/null
        then
                GIT_VALGRIND_ENABLED=t
        fi
@@ -552,6 +567,9 @@ test_done () {
        esac
 }
 
+
+# Set up a directory that we can put in PATH which redirects all git
+# calls to 'valgrind git ...'.
 if test -n "$valgrind"
 then
        make_symlink () {
@@ -599,33 +617,42 @@ then
                make_symlink "$symlink_target" "$GIT_VALGRIND/bin/$base" || exit
        }
 
-       # override all git executables in TEST_DIRECTORY/..
-       GIT_VALGRIND=$TEST_DIRECTORY/valgrind
-       mkdir -p "$GIT_VALGRIND"/bin
-       for file in $GIT_BUILD_DIR/git* $GIT_BUILD_DIR/test-*
-       do
-               make_valgrind_symlink $file
-       done
-       # special-case the mergetools loadables
-       make_symlink "$GIT_BUILD_DIR"/mergetools "$GIT_VALGRIND/bin/mergetools"
-       OLDIFS=$IFS
-       IFS=:
-       for path in $PATH
-       do
-               ls "$path"/git-* 2> /dev/null |
-               while read file
+       # In the case of --valgrind-parallel, we only need to do the
+       # wrapping once, in the main script.  The worker children all
+       # have $valgrind_only_stride set, so we can skip based on that.
+       if test -z "$valgrind_only_stride"
+       then
+               # override all git executables in TEST_DIRECTORY/..
+               GIT_VALGRIND=$TEST_DIRECTORY/valgrind
+               mkdir -p "$GIT_VALGRIND"/bin
+               for file in $GIT_BUILD_DIR/git* $GIT_BUILD_DIR/test-*
                do
-                       make_valgrind_symlink "$file"
+                       make_valgrind_symlink $file
                done
-       done
-       IFS=$OLDIFS
+               # special-case the mergetools loadables
+               make_symlink "$GIT_BUILD_DIR"/mergetools "$GIT_VALGRIND/bin/mergetools"
+               OLDIFS=$IFS
+               IFS=:
+               for path in $PATH
+               do
+                       ls "$path"/git-* 2> /dev/null |
+                       while read file
+                       do
+                               make_valgrind_symlink "$file"
+                       done
+               done
+               IFS=$OLDIFS
+       fi
        PATH=$GIT_VALGRIND/bin:$PATH
        GIT_EXEC_PATH=$GIT_VALGRIND/bin
        export GIT_VALGRIND
        GIT_VALGRIND_MODE="$valgrind"
        export GIT_VALGRIND_MODE
        GIT_VALGRIND_ENABLED=t
-       test -n "$valgrind_only" && GIT_VALGRIND_ENABLED=
+       if test -n "$valgrind_only" || test -n "$valgrind_only_stride"
+       then
+               GIT_VALGRIND_ENABLED=
+       fi
        export GIT_VALGRIND_ENABLED
 elif test -n "$GIT_TEST_INSTALLED"
 then
@@ -711,6 +738,41 @@ then
 else
        mkdir -p "$TRASH_DIRECTORY"
 fi
+
+# Gross hack to spawn N sub-instances of the tests in parallel, and
+# summarize the results.  Note that if this is enabled, the script
+# terminates at the end of this 'if' block.
+if test -n "$valgrind_parallel"
+then
+       for i in $(test_seq 1 $valgrind_parallel)
+       do
+               root="$TRASH_DIRECTORY/vgparallel-$i"
+               mkdir "$root"
+               TEST_OUTPUT_DIRECTORY="$root" \
+                       ${SHELL_PATH} "$0" \
+                       --root="$root" --statusprefix="[$i] " \
+                       --valgrind="$valgrind" \
+                       --valgrind-only-stride="$valgrind_parallel" \
+                       --valgrind-only-offset="$i" &
+               pids="$pids $!"
+       done
+       trap "kill $pids" INT TERM HUP
+       wait $pids
+       trap - INT TERM HUP
+       for i in $(test_seq 1 $valgrind_parallel)
+       do
+               root="$TRASH_DIRECTORY/vgparallel-$i"
+               eval "$(cat "$root/test-results/$(basename "$0" .sh)"-*.counts |
+                       sed 's/^\([a-z][a-z]*\) \([0-9][0-9]*\)/inner_\1=\2/')"
+               test_count=$(expr $test_count + $inner_total)
+               test_success=$(expr $test_success + $inner_success)
+               test_fixed=$(expr $test_fixed + $inner_fixed)
+               test_broken=$(expr $test_broken + $inner_broken)
+               test_failure=$(expr $test_failure + $inner_failed)
+       done
+       test_done
+fi
+
 # Use -P to resolve symlinks in our working directory so that the cwd
 # in subprocesses like git equals our $PWD (for pathname comparisons).
 cd -P "$TRASH_DIRECTORY" || exit 1