Garbage Collection Problem Fixed

Sunday, October 12, 2003

If you've updated and built Emacs from CVS on OS X within the past few weeks, you may have experienced crashes while Emacs is doing garbage collection. The following patch, just checked into CVS, solves the problem. I highly recommend updating to include it.

Index: darwin.h
===================================================================
RCS file: /cvs/emacs/src/s/darwin.h,v
retrieving revision 1.12
diff -r1.12 darwin.h
319a320,323
> /* Use the GC_MAKE_GCPROS_NOOPS (see lisp.h) method for marking the
>    stack.  */
> #define GC_MARK_STACK   GC_MAKE_GCPROS_NOOPS
> 

The problem is caused by a change to src/alloc.c about a month ago that causes garbage collection to crash under certain circumstances (when LISP_INT values are on the gcprolist) if GC_MARK_STACK is set to GC_USE_GCPROS_AS_BEFORE. The best way to fix the problem is probably to fix the bug introduced. I don't want to work on that. Instead I have now set GC_MARK_STACK to GC_MAKE_GCPROS_NOOPS. This option for GC has been chosen on nearly all other platforms. So by following suit on OS X, we may actually be using better-maintained code in the future. This is probably a better solution.