LEAK(1) LEAK(1)
NAME
leak - examine family of processes for memory leaks
SYNOPSIS
leak [ -bs ] [ -f binary ] [ -r res ] [ -x width ] pid ...
DESCRIPTION
Leak examines the named processes, which should be sharing
their data and bss segments, for memory leaks. It uses a
mark and sweep-style algorithm to determine which allocated
blocks are no longer reachable from the set of root point-
ers. The set of root pointers is created by looking through
the shared bss segment as well as each process's registers.
Unless directed otherwise, leak prints, for each block, a
line with five space-separated fields: the string block, the
address of the block, the size of the block, and the first
two words of the block. Usually, the first two words of the
block contain the malloc and realloc tags (see
debugmalloc(2)), useful for finding who allocated the leaked
blocks.
If the -s option is given, leak will instead present a
sequence of acid(1) commands that show each leaky allocation
site. A comment appears next to each command to indicate
how many lost blocks were allocated at that point in the
program.
If the -b option is given, leak will print a Plan 9 image
file graphically summarizing the memory arenas. In the
image, each pixel represents res (default 8) bytes. The
color code is:
dark blue Completely allocated.
bright blue Contains malloc headers.
bright red Contains malloc headers for leaked memory.
dark red Contains leaked memory.
yellow Completely free
white Padding to fill out the image. The bright
pixels representing headers help in counting
the number of blocks. Magnifying the images
with lens(1) is often useful.
If given a name rather than a list of process ids, leak
echoes back a command-line with process ids of every process
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LEAK(1) LEAK(1)
with that name.
The -f option specifies a binary to go on the acid(1)
command-line used to inspect the processes, and is only nec-
essary when inspecting processes started from stripped bina-
ries.
EXAMPLES
List lost blocks in 8.out. This depends on the fact that
there is only once instance of 8.out running; if there were
more, the output of leak -s 8.out would need editing before
sending to the shell.
g% leak -s 8.out
leak -s 229 230
g% leak -s 8.out | rc
src(0x0000bf1b); // 64
src(0x000016f5); // 7
src(0x0000a988); // 7
g%
View the memory usage graphic for the window system.
g% leak -b rio | rc | page
SOURCE
/sys/lib/acid/leak
/sys/src/cmd/aux/acidleak.c
/rc/bin/leak
BUGS
Leak depends on the internal structure of the libc pool mem-
ory allocator (see pool(2)). Since the ANSI/POSIX environ-
ment uses a different allocator, leak will not work on APE
programs.
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