Give Python a debug-mode pymalloc, much as sketched on Python-Dev. When WITH_PYMALLOC is defined, define PYMALLOC_DEBUG to enable the debug allocator. This can be done independent of build type (release or debug). A debug build automatically defines PYMALLOC_DEBUG when pymalloc is enabled. It's a detected error to define PYMALLOC_DEBUG when pymalloc isn't enabled. Two debugging entry points defined only under PYMALLOC_DEBUG: + _PyMalloc_DebugCheckAddress(const void *p) can be used (e.g., from gdb) to sanity-check a memory block obtained from pymalloc. It sprays info to stderr (see next) and dies via Py_FatalError if the block is detectably damaged. + _PyMalloc_DebugDumpAddress(const void *p) can be used to spray info about a debug memory block to stderr. A tiny start at implementing "API family" checks isn't good for anything yet. _PyMalloc_DebugRealloc() has been optimized to do little when the new size is <= old size. However, if the new size is larger, it really can't call the underlying realloc() routine without either violating its contract, or knowing something non-trivial about how the underlying realloc() works. A memcpy is always done in this case. This was a disaster for (and only) one of the std tests: test_bufio creates single text file lines up to a million characters long. On Windows, fileobject.c's get_line() uses the horridly funky getline_via_fgets(), which keeps growing and growing a string object hoping to find a newline. It grew the string object 1000 bytes each time, so for a million-character string it took approximately forever (I gave up after a few minutes). So, also: fileobject.c, getline_via_fgets(): When a single line is outrageously long, grow the string object at a mildly exponential rate, instead of just 1000 bytes at a time. That's enough so that a debug-build test_bufio finishes in about 5 seconds on my Win98SE box. I'm curious to try this on Win2K, because it has very different memory behavior than Win9X, and test_bufio always took a factor of 10 longer to complete on Win2K. It *could* be that the endless reallocs were simply killing it on Win2K even in the release build.

--- a/Include/Python.h	Sat Mar 23 05:58:52 2002 +0000
+++ b/Include/Python.h	Sat Mar 23 10:03:50 2002 +0000
@@ -61,6 +61,15 @@
 
 #include "pyport.h"
 
+/* Debug-mode build with pymalloc implies PYMALLOC_DEBUG.
+ *  PYMALLOC_DEBUG is in error if pymalloc is not in use.
+ */
+#if defined(Py_DEBUG) && defined(WITH_PYMALLOC) && !defined(PYMALLOC_DEBUG)
+#define PYMALLOC_DEBUG
+#endif
+#if defined(PYMALLOC_DEBUG) && !defined(WITH_PYMALLOC)
+#error "PYMALLOC_DEBUG requires WITH_PYMALLOC"
+#endif
 #include "pymem.h"
 
 #include "object.h"