ref: 45a25abc3e2070ce0bdaaa76e786b8343839ece6
dir: /sys/man/1/leak/
.TH LEAK 1 .SH NAME leak, kmem, umem \- help find memory leaks .SH SYNOPSIS .B leak [ .B -abcds ] [ .B -f .I binary ] [ .B -r .I res ] [ .B -x .I width ] .I pid ... .PP .B kmem [ .I kernel ] .PP .B umem .I pid [ .I textfile ] .SH DESCRIPTION .I 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 pointers. The set of root pointers is created by looking through the shared bss segment as well as each process's registers. .PP Unless directed otherwise, .I leak prints, for each block, a line with seven space-separated fields: the string .BR 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. Usually, the first two words of the block contain the malloc and realloc tags (see .IR malloc (2)), useful for finding who allocated the leaked blocks. .PP If the .B -s or the .B -c option is given, .I leak will instead present a sequence of .IR acid (1) commands that show each leaky allocation site. With .B -s a comment appears next to each command to indicate how many lost blocks were allocated at that point in the program. With .B -c the comments 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. .PP If the .B -a option is given, .I leak will print information as decribed above, but for all allocated blocks, not only leaked ones. If the .B -d option is given, .I 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 .B -a and .B -d options can be combined. .PP If the .B -b option is given, .I leak will print a Plan 9 image file graphically summarizing the memory arenas. In the image, each pixel represents .I res (default 8) bytes. The color code is: .TP "\w'\fIbright blue\fR 'u .I "dark blue Completely allocated. .TP .I "bright blue Contains malloc headers. .TP .I "bright red Contains malloc headers for leaked memory. .TP .I "dark red Contains leaked memory. .TP .I "yellow Completely free .TP .I "white Padding to fill out the image. .PD The bright pixels representing headers help in counting the number of blocks. Magnifying the images with .IR lens (1) is often useful. .PP If given a name rather than a list of process ids, .I leak echoes back a command-line with process ids of every process with that name. .PP The .B -f option specifies a binary to go on the .IR acid (1) command-line used to inspect the processes, and is only necessary when inspecting processes started from stripped binaries. .PP .I Umem prints a summary of all allocated blocks in the process with id .IR 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 decreasing order. .I Umem prints summarizes all allocations, not just memory leaks, but it is faster and requires less memory than .IR leak . .PP .I Kmem is like .I umem but prints a summary for the running kernel. .SH EXAMPLES List lost blocks in .IR 8.out . This depends on the fact that there is only one instance of .I 8.out running; if there were more, the output of .B "leak -s 8.out would need editing before sending to the shell. .IP .EX % leak -s 8.out leak -s 229 230 % leak -s 8.out | rc src(0x0000bf1b); // 64 src(0x000016f5); // 7 src(0x0000a988); // 7 % .EE .LP View the memory usage graphic for the window system. .IP .EX % leak -b rio | rc | page .EE .PP List the top allocation points in the kernel, first by count and then by total size: .IP .EX % kmem | sed 10q % kmem | sort -nr +1 | sed 10q .EE .SH SOURCE .B /sys/lib/acid/leak .br .B /sys/src/cmd/aux/acidleak.c .br .B /rc/bin/leak .br .B /rc/bin/kmem .br .B /rc/bin/umem .SH SEE ALSO .IR getcallerpc (2), .I setmalloctag in .IR malloc (2) .SH BUGS .I Leak and .I kmem depend on the internal structure of the libc pool memory allocator (see .IR pool (2)) and require .B /sys/src/libc/port/pool.$objtype.acid to be present and generated from .BR pool.c as follows: .IP .EX % cd /sys/src/libc/port && mk pool.$objtype.acid .EE .PP Since the ANSI/POSIX environment uses a different allocator, .I leak will not work on APE programs. .PP .I Leak is not speedy, and .I acidleak can consume more memory than the process(es) being examined.