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 mem-ory memory
ory 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 pack-ets packets
ets 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 finaliza-tion finalization
tion 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.
SEE ALSO
ckalloc, ckfree, Tcl_ValidateAllMemory, Tcl_DumpActiveMemory, TCL_MEM_DEBUG
KEYWORDS
memory, debug
Tcl 8.1 memory(n)
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