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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 debugging capabilities.
       The memory command has several suboptions, which are described below.  It is  only  avail-
       able  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 itself.  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 number of calls to ckalloc not met by a cor-
	      responding  call to ckfree), 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 onexit file
	      Causes  a  list  of all allocated memory to be written to the specified 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, every 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 ckalloc's 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  identify  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 enabled, on every call
	      to ckalloc or ckfree, the guard zones are checked for every piece  of  memory  cur-
	      rently  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 ckalloc  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)
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