18.4.1 Using dmalloc

In order to use dmalloc do the following:

• Define an alias

  for csh: alias dmalloc 'eval `\dmalloc -C \!*`', 
  for bash: function dmalloc { eval `command dmalloc -b $*` }
  

• Next turn debugging on by typing dmalloc -l logfile low
• Run your program (which was configured and built with dmalloc as described above).
• Interpret logfile by running dmalloc_summarize ns logfile. (You need to download dmalloc_summarize separately.)

On some platforms you may need to link things statically to get dmalloc to work. On Solaris this is done by linking with these options: "-Xlinker -B -Xlinker -static libraries -Xlinker -B -Xlinker -dynamic -ldl -lX11 -lXext". (You'll need to change Makefile. Thanks to Haobo Yu and Doug Smith for working this out.)

We can interpret a sample summary produced from this process on ns-2/tcl/ex/newmcast/cmcast-100.tcl with an exit statement after the 200'th duplex-link-of-interefaces statement:

Ns allocates  6MB of memory.
 1MB is due to TclObject::bind
 900KB is StringCreate, all in 32-byte chunks
 700KB is NewVar, mostly in 24-byte chunks
Dmalloc_summarize must map function names to and from their addresses. It often can't resolve addresses for shared libraries, so if you see lots of memory allocated by things beginning with ``ra='', that's what it is. The best way to avoid this problem is to build ns statically (if not all, then as much as possible).

Dmalloc's memory allocation scheme is somewhat expensive, plus there's bookkeeping costs. Programs linked against dmalloc will consume more memory than against most standard mallocs.

Dmalloc can also diagnose other memory errors (duplicate frees, buffer overruns, etc.). See its documentation for details.