How do I limit the memory usage of a specific process in linux?

Question

I've written a program for a class that my professor will be testing in various low memory environments to see how it behaves when the program runs out of memory. Is there a way I can simulate the execution in a low memory environment without creating a virtual machine?

Solution

You'll want to use ulimit

ulimit can be used to limit memory utilization (among other things)

Here is an example of setting memory usage so low that /bin/ls (which is larger than /bin/cat) no longer works, but /bin/cat still works.

$ ls -lh /bin/ls /bin/cat
-rwxr-xr-x 1 root root 25K May 24 2008 /bin/cat
-rwxr-xr-x 1 root root 88K May 24 2008 /bin/ls
$ date > test.txt
$ ulimit -d 10000 -m 10000 -v 10000
$ /bin/ls date.txt
/bin/ls: error while loading shared libraries: libc.so.6: failed to map segment from shared object: Cannot allocate memory
$ /bin/cat date.txt
Thu Mar 26 11:51:16 PDT 2009
$

Note: If I set the limits to 1000 kilobytes, neither program works, because they load libraries, which increase their size. above 1000 KB.

-d data segment size

-m max memory size

-v virtual memory size

Run ulimit -a to see all the resource caps ulimits can set.

Comments

[user20222]

is there something that does something similar on a single user basis? I don't have the permission to make system wide changes.

[Dennis Williamson]

@user20222: You can use ulimit at the command line or in a script in Bash.

[user20222]

I'm getting-- ulimit: max memory size: cannot modify limit: Operation not permitted

[user20222]

I talked to the sysadmin and I'm not sure what was wrong but he fixed the problem.

[David Schwartz]

Setting -m limits the use of physical RAM on systems that enforce it. Setting -v limits the use of virtual RAM on systems that enforce it.

[Mikko Rantalainen]

Note that -m does nothing on modern Linux kernels. You have to use cgroups to limit physical RAM usage these days. Unfortunately, the user interface to cgroups is still pretty bad.