A complete fix for this problem will have to wait until after 3.81 is released.  I know how I want to solve it, but I'm trying hard to get 3.81 out the door and really need to clamp down on changes.  However, I'd like to fix this issue for gcj.  As you've noted, the code in 3.81 has changed quite a bit in this area (but not because of the hash_* functions; those were used in 3.80 as well--the change is because the code has been rearranged to support the secondary expansion feature).

So, let me ask a question: for this specific situation in gcj and GNU Classpath, are the dependency lines listed as they are in the makefile attached to this bug report?  That is, like this:

  targ1 targ2 targ3 ... : prereq1 prereq2 prereq3 ...

Or, are they broken out into multiple lines, like this:

  targ1: prereq1 prereq2 prereq3 ...
  targ2: prereq1 prereq2 prereq3 ...
  targ3: prereq1 prereq2 prereq3 ...
    ...

?  If the former, I can do a simple, quick fix for 3.81 that will solve the problem and then I can get a more complete solution for the next release.  If that latter... we'll need something much closer to the complete solution to fix the issue.

Hi,

Please consider inclusion of parts of this patch.

Make memory consumption is a real problem to build gcj-4.0 in Debian.  Please see http://bugs.debian.org/342726 for details, but this patch doesn't look too intrusive and helps solving the memory consumption issues by storing hashes of strings instead of strings in memory.

This patch was already sent at:
http://gcc.gnu.org/ml/gcc/2005-12/msg00231.html

and updated at:
http://gcc.gnu.org/ml/gcc/2006-02/msg00026.html

It was written against the stable version of make and only needs to be updated to use make's hash_* functions from CVS.

Cheers,

GNU make 3.80 is a HUGE memory hog. It calls xstrdup to build
dependency list. gnu-src-gcc.deps in libjava has 3000+ targets depend
the same 3000+ files, whose filenames are more than 260K. For this
dependency alone, make takes 3000*260K == 761MB.

This patch is a quick hack. It reduces the memory from 1.6GB to around
600MB for "make -f gnu-src-gcc.deps". I got

[hjl@gnu-13 libjava]$ make
ulimit -v 1048576; \
/usr/bin/time ./make -f gnu-src-gcc.deps
make[1]: Entering directory `/export/home/hjl/bugs/make/libjava'
make[1]: * No rule to make target `../gnu/classpath/Configuration.java',
needed by `lists/gnu-src-gcc.stamp'.  Stop.
make[1]: Leaving directory `/export/home/hjl/bugs/make/libjava'
Command exited with non-zero status 2
67.10user 1.24system 1:16.63elapsed 89%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+140611minor)pagefaults 0swaps
make: * [all] Error 2