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'\"
'\" Copyright (c) 1992-1999 by Karl Lehenbauer and Mark Diekhans
'\" Copyright (c) 2000 by Scriptics Corporation.
'\" All rights reserved.
'\"
'\" RCS: @(#) $Id: memory.n,v 1.2 2000/04/28 00:47:49 ericm Exp $
'\"
.so man.macros
.TH memory n 8.1 Tcl "Tcl Built-In Commands"
.BS
.SH NAME
memory \- Control Tcl memory debugging capabilities.
.SH SYNOPSIS
\fBmemory \fIoption \fR?\fIarg arg ...\fR?
.SH DESCRIPTION
.PP
The \fBmemory\fR 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 \fBTCL_MEM_DEBUG\fR is defined at
compile time).
.TP
\fBmemory info\fR
Produces a report containing the total allocations and frees since
Tcl began, the current packets allocated (the current
number of calls to \fBckalloc\fR not met by a corresponding call
to \fBckfree\fR), the current bytes allocated, and the maximum number
of packets and bytes allocated.
.TP
\fBmemory trace [on|off]\fR
.br
Turns memory tracing on or off. When memory tracing is on, every call
to \fBckalloc\fR causes a line of trace information to be written to
\fIstderr\fR, consisting of the word \fIckalloc\fR, 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:
.CS
ckalloc 40e478 98 tclProc.c 1406
.CE
Calls to \fBckfree\fR are traced in the same manner.
.TP
\fBmemory validate [on|off]\fR
Turns memory validation on or off. When memory validation is enabled,
on every call to \fBckalloc\fR or \fBckfree\fR, the guard zones are
checked for every piece of memory currently in existence that was
allocated by \fBckalloc\fR. 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 \fBckalloc\fR or
\fBckfree\fR 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.
.TP
\fBmemory trace_on_at_malloc\fR \fIcount\fR
Enable memory tracing after \fIcount\fR \fBckalloc\fR's have been performed.
For example, if you enter \fBmemory trace_on_at_malloc 100\fR,
after the 100th call to \fBckalloc\fR, 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.
.TP
\fBmemory break_on_malloc\fR \fIcount\fR
After the \fBcount\fR allocations have been performed, \fBckalloc\fR's
output a message to this effect and that it is now attempting to enter
the C debugger. Tcl will then issue a \fISIGINT\fR signal against itself.
If you are running Tcl under a C debugger, it should then enter the debugger
command mode.
.TP
\fB memory display\fR \fIfile\fR
Write a list of all currently allocated memory to the specified file.
.SH "SEE ALSO"
ckalloc, ckfree, Tcl_ValidateAllMemory, Tcl_DumpActiveMemory, TCL_MEM_DEBUG
.SH KEYWORDS
memory, debug
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