Provided by: tcl8.6-doc_8.6.9+dfsg-2_all bug


       memory - Control Tcl memory debugging capabilities


       memory option ?arg arg ...?


       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
       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 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
              corresponding  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 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 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 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  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
              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 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.


       ckalloc, ckfree, Tcl_ValidateAllMemory, Tcl_DumpActiveMemory, TCL_MEM_DEBUG


       memory, debug