Parallel automake execution: AUTOMAKE_JOBS.

* lib/Automake/Config.in (perl_threads): New global.
* automake.in: Use it.  If the perl supports interpreter-based
threading, then use `threads' and `Thread::Queue'.
(handle_makefile, handle_makefiles_serial): New functions,
factored out from main.
(get_number_of_threads): New function, compute number of threads
to use, based on environment variable `AUTOMAKE_JOBS' and number
of independent makefiles.
(handle_makefiles_threaded): New function.  Spawn threads, use
thread queue to distribute handling the different makefiles.
Collect $exit_code values from threads.
(main): Use new functions.
* aclocal.in: No threads here.
* configure.ac: Substitute PERL_THREADS; enabled with perl >=
5.7.2 and when ithreads are available.
* bootstrap (dosubst): Likewise.
* Makefile.am (do_subst): Likewise.
* lib/Automake/Makefile.am (do_subst): Likewise.
* lib/Automake/ChannelDefs.pm: Use `Automake::Config' and
`threads'.
(verb): Prepend thread ID (tid) to verbose messages.
* lib/Automake/Channels.pm (msg): Before exiting, flush stderr,
needed for worker threads.
* lib/Automake/tests/Makefile.am (TESTS_ENVIRONMENT): Also
include the build tree path, so Config.pm is found.
* tests/parallel-am.test: New test.
* tests/Makefile.am: Update.
* doc/automake.texi (Invoking Automake): Document AUTOMAKE_JOBS.
* NEWS, THANKS: Update.
Report about long execution times by Joakim Tjernlund and others.

Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>

1 files changed, 32 insertions, 0 deletions

diff --git a/configure b/configure
index 235f1a0ba..9452a620f 100755
--- a/configure
+++ b/configure
@@ -610,6 +610,7 @@ MODIFICATION_DELAY
 LN
 HELP2MAN
 TEX
+PERL_THREADS
 PERL
 pkgvdatadir
 APIVERSION
@@ -2378,6 +2379,37 @@ installed, select the one Automake should use using
    { (exit 1); exit 1; }; }
 }
 
+# We require ithreads support, and version 5.7.2 for CLONE.
+{ $as_echo "$as_me:$LINENO: checking whether $PERL supports ithreads" >&5
+$as_echo_n "checking whether $PERL supports ithreads... " >&6; }
+if test "${am_cv_prog_PERL_ithreads+set}" = set; then
+  $as_echo_n "(cached) " >&6
+else
+  if $PERL -e '
+    require 5.007_002;
+    use Config;
+    if ($Config{useithreads})
+      {
+	use threads;
+	use Thread::Queue;
+	exit 0;
+      }
+    exit 1;' >&5 2>&1
+then
+  am_cv_prog_PERL_ithreads=yes
+else
+  am_cv_prog_PERL_ithreads=no
+fi
+fi
+{ $as_echo "$as_me:$LINENO: result: $am_cv_prog_PERL_ithreads" >&5
+$as_echo "$am_cv_prog_PERL_ithreads" >&6; }
+if test $am_cv_prog_PERL_ithreads = yes; then
+  PERL_THREADS=1;
+else
+  PERL_THREADS=0;
+fi
+
+
 # The test suite will skip some tests if tex is absent.
 # Extract the first word of "tex", so it can be a program name with args.
 set dummy tex; ac_word=$2