Setting memory consumption limits with Upstart

Question

I\'ve recently become quite fond of Upstart. Previously I\'ve been using God, Monit and Bluepill but I don\'t really like these solutions so I\'m giving Upstart a try.

I

Answer 1

From the Upstart docs, the limits come from the rlimit system call options. (http://upstart.ubuntu.com/cookbook/#limit)

Since Linux 2.4+ setting the rss (Resident Set Size) has no effect.

An alternative already suggested in other answers is as which sets the virtual memory Address Space size limits. This will have a very different effect of setting 'real' memory limits.

limit as <soft limit> <hard limit>

Excerpt from man pages for setrlimit:

RLIMIT_AS The maximum size of the process's virtual memory (address space) in bytes. This limit affects calls to brk(2), mmap(2), and mremap(2), which fail with the error ENOMEM upon exceeding this limit. Also automatic stack expansion will fail (and generate a SIGSEGV that kills the process if no alternate stack has been made available via sigaltstack(2)). Since the value is a long, on machines with a 32-bit long either this limit is at most 2 GiB, or this resource is unlimited.

Answer 2

Appending this to the end of myapp-web-*.conf will cause any allocation calls trying to allocate more than 150mb of memory to return ENOMEM:

limit rss 157286400 157286400

The process might crash at this point, or it might not. That's up to the process!

Here's a test for this in the Upstart Source.