On 05/14/2013 12:49 AM, Alexandre Oliva wrote:
However, rather than implementing the locking in Makefiles, I'm thinking
it might be wiser to do so in a script that takes the lock name and the
command to run while holding the lock.
Good point.
trap 'rmdir "$lockdir"; exit $status' 0 1 2 15
In my testing I found that trapping signals other than 0 resulted in
trying to rmdir twice if the process is interrupted. The extra exit
here also seems unnecessary. And I added a check so that the script
gives up and steals the lock after waiting 5 minutes.
2013-05-14 Jason Merrill <ja...@redhat.com>
* Makefile.in (LLINKER): New variable.
* configure.ac: Handle --enable-link-mutex.
* lock-and-run.sh: New script.
diff --git a/gcc/lock-and-run.sh b/gcc/lock-and-run.sh
new file mode 100644
index 0000000..8beac5a
--- /dev/null
+++ b/gcc/lock-and-run.sh
@@ -0,0 +1,27 @@
+#! /bin/bash
+# Shell-based mutex using mkdir.
+
+lockdir=$1 prog=$2; shift 2 || exit 1
+count=0
+# Remember when we started trying to acquire the lock.
+touch lock-stamp.$$
+trap 'rm -r "$lockdir" lock-stamp.$$' 0
+until mkdir "$lockdir" 2>/dev/null; do
+ # Say something periodically in case the lock is stale.
+ if [ $((count++ % 30)) == 0 ]; then
+ # Reset if the lock has been renewed.
+ if [ "$lockdir" -nt lock-stamp.$$ ]; then
+ touch lock-stamp.$$
+ count=0
+ # Give up after 5 minutes.
+ elif [ $count == 300 ]; then
+ echo removing stale $lockdir
+ rm -r "$lockdir"
+ else
+ echo waiting to acquire $lockdir
+ fi
+ fi
+ sleep 1
+done
+echo $prog "$@"
+$prog "$@"
diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 903125e..b7ade78 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -235,6 +235,13 @@ LINKER = $(CC)
LINKER_FLAGS = $(CFLAGS)
endif
+# Like LINKER, but use a mutex for serializing front end links.
+ifeq (@DO_LINK_MUTEX@,true)
+LLINKER = $(SHELL) $(srcdir)/lock-and-run.sh linkfe.lck $(LINKER)
+else
+LLINKER = $(LINKER)
+endif
+
# -------------------------------------------
# Programs which operate on the build machine
# -------------------------------------------
diff --git a/gcc/ada/gcc-interface/Make-lang.in b/gcc/ada/gcc-interface/Make-lang.in
index ef12b4b..4fed34f 100644
--- a/gcc/ada/gcc-interface/Make-lang.in
+++ b/gcc/ada/gcc-interface/Make-lang.in
@@ -185,6 +185,7 @@ endif
GCC_LINKERFLAGS = $(filter-out -Werror, $(ALL_LINKERFLAGS))
GCC_LINK=$(LINKER) $(GCC_LINKERFLAGS) $(LDFLAGS)
+GCC_LLINK=$(LLINKER) $(GCC_LINKERFLAGS) $(LDFLAGS)
# Lists of files for various purposes.
@@ -562,7 +563,8 @@ TARGET_ADA_SRCS =
# Since the RTL should be built with the latest compiler, remove the
# stamp target in the parent directory whenever gnat1 is rebuilt
gnat1$(exeext): $(TARGET_ADA_SRCS) $(GNAT1_OBJS) $(ADA_BACKEND) libcommon-target.a $(LIBDEPS)
- +$(GCC_LINK) -o $@ $(GNAT1_OBJS) $(ADA_BACKEND) libcommon-target.a $(LIBS) $(SYSLIBS) $(BACKENDLIBS) $(CFLAGS)
+ +$(GCC_LLINK) -o $@ $(GNAT1_OBJS) $(ADA_BACKEND) \
+ libcommon-target.a $(LIBS) $(SYSLIBS) $(BACKENDLIBS) $(CFLAGS)
$(RM) stamp-gnatlib2-rts stamp-tools
gnatbind$(exeext): ada/b_gnatb.o $(CONFIG_H) $(GNATBIND_OBJS) ggc-none.o libcommon-target.a $(LIBDEPS)
diff --git a/gcc/c/Make-lang.in b/gcc/c/Make-lang.in
index 8310e0a..47aa4cb 100644
--- a/gcc/c/Make-lang.in
+++ b/gcc/c/Make-lang.in
@@ -75,7 +75,7 @@ cc1-checksum.c : build/genchecksum$(build_exeext) checksum-options \
cc1-checksum.o : cc1-checksum.c $(CONFIG_H) $(SYSTEM_H)
cc1$(exeext): $(C_OBJS) cc1-checksum.o $(BACKEND) $(LIBDEPS)
- +$(LINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ $(C_OBJS) \
+ +$(LLINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ $(C_OBJS) \
cc1-checksum.o $(BACKEND) $(LIBS) $(BACKENDLIBS)
#
# Build hooks:
diff --git a/gcc/configure b/gcc/configure
index 39e911c..1f03eac 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -670,6 +670,7 @@ subdirs
dollar
gcc_tooldir
enable_lto
+DO_LINK_MUTEX
MAINT
zlibinc
zlibdir
@@ -916,6 +917,7 @@ with_long_double_128
with_gc
with_system_zlib
enable_maintainer_mode
+enable_link_mutex
enable_version_specific_runtime_libs
enable_plugin
enable_libquadmath_support
@@ -1627,6 +1629,8 @@ Optional Features:
--enable-maintainer-mode
enable make rules and dependencies not useful (and
sometimes confusing) to the casual installer
+ --enable-link-mutex avoid linking multiple front-ends at once to avoid
+ thrashing on the build machine
--enable-version-specific-runtime-libs
specify that runtime libraries should be installed
in a compiler-specific directory
@@ -17830,7 +17834,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 17833 "configure"
+#line 17837 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -17936,7 +17940,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 17939 "configure"
+#line 17943 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -27061,6 +27065,26 @@ else
MAINT='#'
fi
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to avoid linking multiple front-ends at once" >&5
+$as_echo_n "checking whether to avoid linking multiple front-ends at once... " >&6; }
+ # Check whether --enable-link-mutex was given.
+if test "${enable_link_mutex+set}" = set; then :
+ enableval=$enable_link_mutex; do_link_mutex=$enableval
+else
+ do_link_mutex=no
+fi
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $do_link_mutex" >&5
+$as_echo "$do_link_mutex" >&6; }
+
+if test "$do_link_mutex" = "yes"; then
+ DO_LINK_MUTEX=true
+else
+ DO_LINK_MUTEX=false
+fi
+
+
# --------------
# Language hooks
# --------------
diff --git a/gcc/configure.ac b/gcc/configure.ac
index a6cdf24..855affd 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -4958,6 +4958,24 @@ else
fi
AC_SUBST(MAINT)dnl
+dnl Whether to prevent multiple front-ends from linking at the same time
+
+AC_MSG_CHECKING([whether to avoid linking multiple front-ends at once])
+ AC_ARG_ENABLE(link-mutex,
+[AS_HELP_STRING([--enable-link-mutex],
+ [avoid linking multiple front-ends at once to avoid thrashing
+ on the build machine])],
+ do_link_mutex=$enableval,
+ do_link_mutex=no)
+AC_MSG_RESULT($do_link_mutex)
+
+if test "$do_link_mutex" = "yes"; then
+ DO_LINK_MUTEX=true
+else
+ DO_LINK_MUTEX=false
+fi
+AC_SUBST(DO_LINK_MUTEX)
+
# --------------
# Language hooks
# --------------
diff --git a/gcc/cp/Make-lang.in b/gcc/cp/Make-lang.in
index cda4897..df8ed3e 100644
--- a/gcc/cp/Make-lang.in
+++ b/gcc/cp/Make-lang.in
@@ -100,7 +100,7 @@ cc1plus-checksum.c : build/genchecksum$(build_exeext) checksum-options \
cc1plus-checksum.o : cc1plus-checksum.c $(CONFIG_H) $(SYSTEM_H)
cc1plus$(exeext): $(CXX_OBJS) cc1plus-checksum.o $(BACKEND) $(LIBDEPS)
- +$(LINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
+ +$(LLINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
$(CXX_OBJS) cc1plus-checksum.o $(BACKEND) $(LIBS) $(BACKENDLIBS)
ifeq ($(ENABLE_MAINTAINER_RULES), true)
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 1265129..7d7a5c7 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -1293,6 +1293,13 @@ opposite effect. If neither option is specified, the configure script
will try to guess whether the @code{.init_array} and
@code{.fini_array} sections are supported and, if they are, use them.
+@item --enable-link-mutex
+When building GCC, use a mutex to avoid linking the compilers for
+multiple languages at the same time, to avoid thrashing on build
+systems with limited free memory. This functionality requires that
+the default shell be bash, as it uses the 'trap' built-in command.
+The default is not to use such a mutex.
+
@item --enable-maintainer-mode
The build rules that regenerate the Autoconf and Automake output files as
well as the GCC master message catalog @file{gcc.pot} are normally
diff --git a/gcc/fortran/Make-lang.in b/gcc/fortran/Make-lang.in
index c3f826c..ee70423 100644
--- a/gcc/fortran/Make-lang.in
+++ b/gcc/fortran/Make-lang.in
@@ -98,7 +98,7 @@ gfortran-cross$(exeext): gfortran$(exeext)
# The compiler itself is called f951.
f951$(exeext): $(F95_OBJS) \
$(BACKEND) $(LIBDEPS) attribs.o
- +$(LINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
+ +$(LLINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
$(F95_OBJS) $(BACKEND) $(ZLIB) $(LIBS) attribs.o \
$(BACKENDLIBS)
diff --git a/gcc/go/Make-lang.in b/gcc/go/Make-lang.in
index dd98080..5fe4083 100644
--- a/gcc/go/Make-lang.in
+++ b/gcc/go/Make-lang.in
@@ -76,7 +76,7 @@ GO_OBJS = \
go/unsafe.o
go1$(exeext): $(GO_OBJS) attribs.o $(BACKEND) $(LIBDEPS)
- +$(CXX) $(ALL_CXXFLAGS) $(LDFLAGS) -o $@ \
+ +$(LLINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
$(GO_OBJS) attribs.o $(BACKEND) $(LIBS) $(BACKENDLIBS)
# Documentation.
diff --git a/gcc/java/Make-lang.in b/gcc/java/Make-lang.in
index 7ed3220..8a6210f 100644
--- a/gcc/java/Make-lang.in
+++ b/gcc/java/Make-lang.in
@@ -99,7 +99,7 @@ jvspec.o-warn = -Wno-error
jc1$(exeext): $(JAVA_OBJS) $(BACKEND) $(LIBDEPS) attribs.o
rm -f $@
- +$(LINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
+ +$(LLINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
$(JAVA_OBJS) $(BACKEND) $(ZLIB) $(LIBICONV) $(LIBS) attribs.o $(BACKENDLIBS)
jcf-dump$(exeext): $(JCFDUMP_OBJS) $(LIBDEPS)
diff --git a/gcc/lto/Make-lang.in b/gcc/lto/Make-lang.in
index a0bdc26..22df32c 100644
--- a/gcc/lto/Make-lang.in
+++ b/gcc/lto/Make-lang.in
@@ -71,7 +71,7 @@ lto.stagefeedback:
lto-warn = $(STRICT_WARN)
$(LTO_EXE): $(LTO_OBJS) $(BACKEND) $(LIBDEPS)
- +$(LINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
+ +$(LLINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
$(LTO_OBJS) $(BACKEND) $(BACKENDLIBS) $(LIBS)
# Dependencies
diff --git a/gcc/objc/Make-lang.in b/gcc/objc/Make-lang.in
index 9e005c1..f04d606 100644
--- a/gcc/objc/Make-lang.in
+++ b/gcc/objc/Make-lang.in
@@ -68,7 +68,7 @@ cc1obj-checksum.c : build/genchecksum$(build_exeext) checksum-options \
cc1obj-checksum.o : cc1obj-checksum.c $(CONFIG_H) $(SYSTEM_H)
cc1obj$(exeext): $(OBJC_OBJS) $(C_AND_OBJC_OBJS) cc1obj-checksum.o $(BACKEND) $(LIBDEPS)
- +$(LINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
+ +$(LLINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
$(OBJC_OBJS) $(C_AND_OBJC_OBJS) cc1obj-checksum.o \
$(BACKEND) $(LIBS) $(BACKENDLIBS)
diff --git a/gcc/objcp/Make-lang.in b/gcc/objcp/Make-lang.in
index 731ca9e..ec10fc8 100644
--- a/gcc/objcp/Make-lang.in
+++ b/gcc/objcp/Make-lang.in
@@ -72,7 +72,7 @@ cc1objplus-checksum.c : build/genchecksum$(build_exeext) checksum-options \
cc1objplus-checksum.o : cc1objplus-checksum.c $(CONFIG_H) $(SYSTEM_H)
cc1objplus$(exeext): $(OBJCXX_OBJS) cc1objplus-checksum.o $(BACKEND) $(LIBDEPS)
- +$(LINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
+ +$(LLINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
$(OBJCXX_OBJS) cc1objplus-checksum.o $(BACKEND) $(LIBS) $(BACKENDLIBS)
# Objective C++ language specific files.
