Provided by:
manpages-zh_1.5.2-1_all 
NAME
ckalloc, memory, ckfree, Tcl_DisplayMemory, Tcl_InitMemory,
Tcl_ValidateAllMemory -
SYNOPSIS
memory info
memory trace [on|off]
memory validate [on|off]
memory trace_on_at_malloc nnn
memory break_on_malloc nnn
memory display file
#include <tcl.h>
char *
ckalloc (unsigned size)
void
ckfree (char *ptr)
int
Tcl_DumpActiveMemory (char *fileName);
void
Tcl_ValidateAllMemory (char *file,
int line)
void
Tcl_InitMemory (interp)
ARGUMENTS
Tcl_Interp *fileName uint size in
char *ptr in Tcl_Interp *interp in A pointer to the Tcl interpreter.
char *file in The filename of the caller of Tcl_ValidateAllMemory. int
line in The line number of the caller of Tcl_ValidateAllMemory. char
*fileName in File to display list of active memory.
DESCRIPTION
ckalloc
This macro allocates memory, in the same manner as malloc, with the
following differences: One, ckalloc checks the value returned from
malloc (it calls malloc for you) and panics if the allocation request
fails. Two, if enabled at compile time, a version of ckalloc with
special memory debugging capabilities replaces the normal version of
ckalloc, which aids in detecting memory overwrites and leaks (repeated
allocations not matched by corresponding frees).
Parameters:
o size - The size of the memory block to be allocated.
Returns:
A pointer to the allocated memory block.
ckfree
This macro frees memory allocated by ckalloc. Like ckalloc, when
memory debugging is enabled, ckfree has enhanced capabilities for
detecting memory overwrites and leaks.
It is very important that you use ckalloc when you need to allocate
memory, and that you use ckfree to free it. Should you use malloc to
allocate and ckfree to free, spurious memory validation errors will
occur when memory debugging is enabled. Should you use free to free
memory allocated by ckalloc, memory corruption will occur when memory
debugging is enabled. Any memory that is to be become the property of
the Tcl interpreter, such as result space, must be allocated with
ckalloc. If it is absolutely necessary for an application to pass back
malloced memory to Tcl, it will work only if Tcl is complied with the
TCL_MEM_DEBUG flag turned off. If you convert your application to use
this facility, it will help you find memory over runs and lost memory.
Note that memory allocated by a C library routine requiring freeing
should still be freed with free, since it calls malloc rather than
ckalloc to do the allocation.
Parmeters:
o ptr - The address of a block to free, as returned by ckalloc.
Tcl_DumpActiveMemory
This function will output a list of all currently allocated memory to
the specified file. The following information is outputted for each
allocated block of memory: starting and ending addresses (excluding
guard zone), size, source file where ckalloc was called to allocate the
block and line number in that file. It is especially useful to call
Tcl_DumpActiveMemory after the Tcl interpreter has been deleted.
Parameters:
o fileName - The name of the file to output the memory list to.
Tcl_ValidateAllMemory
Forces a validation of the guard zones of all currently allocated
blocks of memory. Normally validation of a block occurs when its
freed, unless full validation is enabled, in which case validation of
all blocks occurs when ckalloc and ckfree are called. This function
forces the validation to occur at any point.
Parameters:
o file - The file that this routine is being called from, normally
__FILE__.
o line - The line that this routine is being called from, normally
__LINE__.
ENABLING MEMORY DEBUGGING
To enable memory debugging, Tcl should be recompiled from scratch with
TCL_MEM_DEBUG defined. This will also compile in a non-stub version of
Tcl_InitMemory to add the memory command to Tcl.
TCL_MEM_DEBUG must be either left defined for all modules or undefined
for all modules that are going to be linked together. If they are not,
link errors will occur, with either TclDbCkfree and Tcl_DbCkalloc or
Tcl_Ckalloc and Tcl_Ckfree being undefined.
GUARD ZONES
When memory debugging is enabled, whenever a call to ckalloc is made,
slightly more memory than requested is allocated so the memory
debugging code can keep track of the allocated memory, and also eight-
byte ``guard zones'' are placed in front of and behind the space that
will be returned to the caller. (The size of the guard zone is defined
by the C #define GUARD_SIZE in baseline/src/ckalloc.c -- it can be
extended if you suspect large overwrite problems, at some cost in
performance.) A known pattern is written into the guard zones and, on
a call to ckfree, the guard zones of the space being freed are checked
to see if either zone has been modified in any way. If one has been,
the guard bytes and their new contents are identified, and a ``low
guard failed'' or ``high guard failed'' message is issued. The ``guard
failed'' message includes the address of the memory packet and the file
name and line number of the code that called ckfree. This allows you
to detect the common sorts of one-off problems, where not enough space
was allocated to contain the data written, for example.
THE MEMORY COMMAND
memory options
The Tcl memory command gives the Tcl developer control of Tcl's
memory debugging capabilities. The memory command has several
suboptions, which are described below. It is only available
when Tcl has been compiled with memory debugging enabled.
memory info
Tcl ()( ckfree ckalloc )
memory trace [on|off]
ckalloc stderr ckalloc C :...
ckalloc 40e478 98 tclProc.c 1406
Calls to ckfree are traced in the same manner, except that the
word ckalloc is replaced by the word ckfree.
memory validate [on|off]
(validation)ckalloc ckfree ckalloc (guard zone)(overwrite)
ckalloc ckfree
memory trace_on_at_malloc nnn
count ckalloc memory trace_on_at_malloc 100 100 ckalloc (
sets in)(judicious)() Tcl
memory break_on_malloc nnn
count ckalloc () C Tcl SIGINT C Tcl
memory display file
DEBUGGING DIFFICULT MEMORY CORRUPTION PROBLEMS
Normally, Tcl compiled with memory debugging enabled will make it easy
to isolate a corruption problem. Turning on memory validation with the
memory command can help isolate difficult problems. If you suspect (or
know) that corruption is occurring before the Tcl interpreter comes up
far enough for you to issue commands, you can set MEM_VALIDATE define,
recompile tclCkalloc.c and rebuild Tcl. This will enable memory
validation from the first call to ckalloc, again, at a large
performance impact.
If you are desperate and validating memory on every call to ckalloc and
ckfree isn't enough, you can explicitly call Tcl_ValidateAllMemory
directly at any point. It takes a char * and an int which are normally
the filename and line number of the caller, but they can actually be
anything you want. Remember to remove the calls after you find the
problem.
KEYWORDS
ckalloc, ckfree, free, memory, malloc
[]
[]
2001/09/28
Linux man :
http://cmpp.linuxforum.net