It seems you are talking about PERL_DESTRUCT_LEVEL rather than PERL_DESTRUCTOR_LEVEL. Thank theorbtwo for motivating a more thorough search.

You can find more out about it by reading the perlhack.pod that comes with 5.8. In short, setting it to two should allow you to see what memory perl is expecting to be cleaned up at exit() and hasn't explicitly cleaned up itself.

If you are asking in reference to mod_perl, it seems the apache module uses the same variable for other stuff. Read the mod_perl docs for info.

-sauoq
"My two cents aren't worth a dime.";