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memory(n)		     Tcl Built-In Commands		     memory(n)

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NAME
       memory -	Control	Tcl memory debugging capabilities

SYNOPSIS
       memory option ?arg arg ...?
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DESCRIPTION
       The  memory command gives the Tcl developer control of Tcl's memory de-
       bugging capabilities.  The memory command has several suboptions, which
       are  described  below.  It is only available when Tcl has been compiled
       with memory debugging enabled (when TCL_MEM_DEBUG is defined at compile
       time), and after	Tcl_InitMemory has been	called.

       memory active file
	      Write  a list of all currently allocated memory to the specified
	      file.

       memory break_on_malloc count
	      After the	count allocations have been performed, ckalloc outputs
	      a	 message to this effect	and that it is now attempting to enter
	      the C debugger.  Tcl will	then issue a SIGINT signal against it-
	      self.  If	you are	running	Tcl under a C debugger,	it should then
	      enter the	debugger command mode.

       memory info
	      Returns a	report containing  the	total  allocations  and	 frees
	      since Tcl	began, the current packets allocated (the current num-
	      ber of calls to ckalloc not met by a corresponding call  to  ck-
	      free),  the  current  bytes allocated, and the maximum number of
	      packets and bytes	allocated.

       memory init [on|off]
	      Turn on or off the pre-initialization of	all  allocated	memory
	      with bogus bytes.	 Useful	for detecting the use of uninitialized
	      values.

       memory objs file
	      Causes a list of all allocated Tcl_Obj values to be  written  to
	      the  specified  file  immediately, together with where they were
	      allocated.  Useful for checking for leaks	of values.

       memory onexit file
	      Causes a list of all allocated memory to be written to the spec-
	      ified  file  during  the finalization of Tcl's memory subsystem.
	      Useful for checking that memory is properly  cleaned  up	during
	      process exit.

       memory tag string
	      Each  packet  of memory allocated	by ckalloc can have associated
	      with it a	string-valued tag.  In the lists of  allocated	memory
	      generated	 by  memory active and memory onexit, the tag for each
	      packet is	printed	along with other information about the packet.
	      The  memory  tag command sets the	tag value for subsequent calls
	      to ckalloc to be string.

       memory trace [on|off]
	      Turns memory tracing on or off.  When memory tracing is on,  ev-
	      ery  call	 to  ckalloc  causes a line of trace information to be
	      written to stderr, consisting of the word	ckalloc,  followed  by
	      the  address returned, the amount	of memory allocated, and the C
	      filename and line	number of the code performing the  allocation.
	      For example:

		     ckalloc 40e478 98 tclProc.c 1406

	      Calls to ckfree are traced in the	same manner.

       memory trace_on_at_malloc count
	      Enable  memory tracing after count ckallocs have been performed.
	      For example, if you enter	memory trace_on_at_malloc  100,	 after
	      the  100th  call to ckalloc, memory trace	information will begin
	      being displayed for all allocations and frees.  Since there  can
	      be  a  lot of memory activity before a problem occurs, judicious
	      use of this option can reduce the	 slowdown  caused  by  tracing
	      (and the amount of trace information produced), if you can iden-
	      tify a number of allocations that	occur before the problem  sets
	      in.  The current number of memory	allocations that have occurred
	      since Tcl	started	is printed on a	guard zone failure.

       memory validate [on|off]
	      Turns memory validation on or off. When memory validation	is en-
	      abled,  on  every	call to	ckalloc	or ckfree, the guard zones are
	      checked for every	piece of memory	currently  in  existence  that
	      was  allocated  by ckalloc.  This	has a large performance	impact
	      and should only be used when  overwrite  problems	 are  strongly
	      suspected.   The advantage of enabling memory validation is that
	      a	guard zone overwrite can be detected on	the first call to  ck-
	      alloc  or	 ckfree	after the overwrite occurred, rather than when
	      the specific memory with the overwritten guard zone(s) is	freed,
	      which may	occur long after the overwrite occurred.

SEE ALSO
       ckalloc,	    ckfree,    Tcl_ValidateAllMemory,	 Tcl_DumpActiveMemory,
       TCL_MEM_DEBUG

KEYWORDS
       memory, debug

Tcl				      8.1			     memory(n)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | KEYWORDS

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