memory(n) manual page
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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 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 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
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