Avoid parallel GCC install in build-many-glibcs.py [committed]

[Joseph Myers <joseph at codesourcery dot com>]

A recent build-many-glibcs.py build
<https://sourceware.org/ml/libc-testresults/2017-q1/msg00067.html> ran
into what proves to be an old known bug
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42980> with parallel
install of GCC (one which as discussed there might require automake
changes to fix).  This patch makes build-many-glibcs.py avoid such
intermittent failures from parallel install by using -j1 for GCC make
install (the code in question also applies to binutils make install,
but it doesn't seem worth trying to avoid -j1 there; the builds and
installs of different toolchains are still fully parallel with each
other, this is only about the case when there are few enough of those
that multiple jobs can get used within a single make install).

Committed.

2017-01-18  Joseph Myers  <joseph@codesourcery.com>

	* scripts/build-many-glibcs.py (Config.build_cross_tool): Use -j1
	for make install.

diff --git a/scripts/build-many-glibcs.py b/scripts/build-many-glibcs.py
index d27e70b..d2947e6 100755
--- a/scripts/build-many-glibcs.py
+++ b/scripts/build-many-glibcs.py
@@ -1173,7 +1173,17 @@ class Config(object):
             cfg_cmd.extend(extra_opts)
         cmdlist.add_command('configure', cfg_cmd)
         cmdlist.add_command('build', ['make'])
-        cmdlist.add_command('install', ['make', 'install'])
+        # Parallel "make install" for GCC has race conditions that can
+        # cause it to fail; see
+        # <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42980>.  Such
+        # problems are not known for binutils, but doing the
+        # installation in parallel within a particular toolchain build
+        # (as opposed to installation of one toolchain from
+        # build-many-glibcs.py running in parallel to the installation
+        # of other toolchains being built) is not known to be
+        # significantly beneficial, so it is simplest just to disable
+        # parallel install for cross tools here.
+        cmdlist.add_command('install', ['make', '-j1', 'install'])
         cmdlist.cleanup_dir()
         cmdlist.pop_subdesc()
 

-- 
Joseph S. Myers
joseph@codesourcery.com