What does ACL2 exit code 137 mean?

Question

What does ACL2 exit code 137 mean? The output reads like this:

Form:  ( INCLUDE-BOOK "centaur/ubdds/param" ...)
Rules: NIL
Time:  0.00 seconds (prove: 0.00, print: 0.00, other: 0.00)
:REDUNDANT
Note: not introducing any A4VEC field bindings for A, since none of
its fields appear to be used.
Note: not introducing any MODSCOPE field bindings for SCOPE, since
none of its fields appear to be used.


;;; Starting full GC,  10,736,500,736 bytes allocated.
Exit code from ACL2 is 137
top.cert seems to be missing

Answer 1

Looks like "Linux OOM killer" killed your program.

Exit status 137 means program was terminated with singal 9 (SIGKILL) (See here):

When a command terminates on a fatal signal whose number is N, Bash uses the value 128+N as the exit status.

128+9=137

This message from the log tells us that your ACL2 proof consumed 10Gb of memory:

;;; Starting full GC, 10,736,500,736 bytes allocated.

Linux has a feature where it kills an offending process when the system is very low on memory. It is called OOM Killer: https://www.kernel.org/doc/gorman/html/understand/understand016.html

Such events are logged by kernel. You can immediately see them just to make sure:

$ dmesg |grep -i "killed process"
Mar  7 02:43:11 myhost kernel: Killed process 3841 (acl2) total-vm:128024kB, anon-rss:0kB, file-rss:0kB

There are two ACL2 calls : set-max-mem and maybe-wash-memory which you can use to control memory consumtion.

(include-book "centaur/misc/memory-mgmt" :dir :system) ;; adds ttag
(value-triple (set-max-mem (* 4 (expt 2 30))))           ;; 4 GB

Unfortunately these two calls do not guarantee that memory will be freed. Consider using a more powerful computer for your proof.

Answer 2

An exit code of 137 suggests that it has been killed by bash with -9

Reference: http://www.tldp.org/LDP/abs/html/exitcodes.html