dec_notes

减少内存碎片的malloc分配函数

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$Id: dec_notes,v 1.7 2000/03/21 20:13:02 gray Exp $
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From Dave Hill:
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DEC OSF1/AXP extra notes:
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To build this library, you will need to have -std1 as a flag to cc in
the Makefile.  This sets the compiler into ansi-mode.  The configure
script may have done this for you, but if not, the Makefile should
read:

	# default c-compiler
	CC = cc -std1

To create a shared library from the static library:

	ld -shared -o libdmalloc.so -all libdmalloc.a -all \
		-soname libdmalloc.so -none -lc

The OSF1/AXP shared library loader has the capabilities to override the
shared libraries used, even to the extent that it takes symbols from a
library that the program was not linked with.  Using this technique, you
may override the standard malloc in libc with the debug malloc shared
library.

	_RLD_LIST=/path_to_the_dir/libdmalloc.so:DEFAULT;export _RLD_LIST

Remember though, setting this variable will affect ALL commands invoked
from the shell that it is set inside of.  You may wish to do this inside
of a shell script that sets the variable just before starting your
program.  Another option with sh and ksh is to list the environment
variables on the program invocation line, for example:

	_RLD_LIST=/path_to_the_dir/libdmalloc.so:DEFAULT program

This command will set the specified env variable and then run program.

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[The dmalloc library currently supports the at_exit() auto-shutdown
routine.  If this is not working, however, you may want to consider
the following.]

OSF1 also supports the use of an 'init' and a 'fini' routine. Any function
prefixed with '__init_' will be executed prior to main() and any function
prefixed with '__fini_' will be executed after any call to exit() or
after main() returns.

A fini routine can be used with the debug library to invoke dmalloc_shutdown
to get final statistics from the library package. For example:

	void
	__fini_dmalloc()
	{
	    dmalloc_shutdown();
	}

Try putting this code in a separate .o file and linking it into your
application when you are debugging.