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LEAK(1)                     General Commands Manual                    LEAK(1)



NAME
       leak, kmem, umem - help find memory leaks

SYNOPSIS
       leak [ -abcds ] [ -f binary ] [ -r res ] [ -x width ] pid ...

       kmem [ kernel ]

       umem pid [ textfile ]

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 al‐
       gorithm  to  determine  which  allocated blocks are no longer reachable
       from the set of root pointers.  The set of root pointers is created  by
       looking through the shared bss segment as well as each process's regis‐
       ters.

       Unless directed otherwise, leak prints, for each  block,  a  line  with
       seven  space-separated  fields:  the  string  block, the address of the
       block, the size of the block, the first two words of the block, and the
       function  names  represented by the first two words of the block.  Usu‐
       ally, the first two words of the block contain the malloc  and  realloc
       tags  (see  malloc(2)),  useful  for  finding  who allocated the leaked
       blocks.

       If the -s or the -c option is given, leak will instead  present  a  se‐
       quence  of acid(1) commands that show each leaky allocation site.  With
       -s a comment appears next to each command to  indicate  how  many  lost
       blocks  were  allocated at that point in the program.  With -c the com‐
       ments are extended to indicate also the total number of bytes  lost  at
       that  point  in  the  program, and an additional comment line gives the
       overall total number of bytes.

       If the -a option is given, leak  will  print  information  as  decribed
       above,  but  for all allocated blocks, not only leaked ones.  If the -d
       option is given, leak will print information as decribed above, but for
       all  free  blocks,  i.e.  those freed, or those that are not yet in use
       (fragmentation?).  The -a and -d options can be combined.

       If the -b option is given, leak will print a Plan 9 image file  graphi‐
       cally  summarizing  the memory arenas.  In the image, each pixel repre‐
       sents 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  repre‐
                     senting  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 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 necessary  when  inspecting  pro‐
       cesses started from stripped binaries.

       Umem  prints  a  summary of all allocated blocks in the process with id
       pid.  Each line of the summary gives the count and total size of blocks
       allocated  at  an allocation point.  The list is sorted by count in de‐
       creasing order.  Umem prints summarizes all allocations, not just  mem‐
       ory leaks, but it is faster and requires less memory than leak .

       Kmem is like umem but prints a summary for the running kernel.

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.

              % leak -s 8.out
              leak -s 229 230
              % leak -s 8.out | rc
              src(0x0000bf1b); // 64
              src(0x000016f5); // 7
              src(0x0000a988); // 7
              %

       View the memory usage graphic for the window system.

              % leak -b rio | rc | page

       List  the  top allocation points in the kernel, first by count and then
       by total size:

              % kmem | sed 10q
              % kmem | sort -nr +1 | sed 10q

SOURCE
       /sys/lib/acid/leak
       /sys/src/cmd/aux/acidleak.c
       /rc/bin/leak
       /rc/bin/kmem
       /rc/bin/umem

SEE ALSO
       getcallerpc(2), setmalloctag in malloc(2)

BUGS
       Leak and kmem depend on the internal structure of the libc pool  memory
       allocator  (see pool(2)).  Since the ANSI/POSIX environment uses a dif‐
       ferent allocator, leak will not work on APE programs.

       Leak is not speedy, and acidleak  can  consume  more  memory  than  the
       process(es) being examined.

       These  commands  require /sys/src/libc/port/pool.acid to be present and
       generated from pool.c.



                                                                       LEAK(1)