Public bug reported:

When testing some algorithm I ran the test program several times with
different parameters. It was to be expected that each run takes about
four hours, and to utilize the capacities of my computer (4 CPUs) I
started the program 4 times running in parallel and with lowered
priority (the latter to be able to do meanwhile something else on the
computer).  All four processes ran in parallel for a few minutes but
then two of them were killed with the error message:

Command terminated by signal 9
[1]   Exit 137                /usr/bin/time -f '%U+%S sec, avg %Kk max %Mk 
memory, major %F minor %R faults, %I+%O i/o' ./testu01long -d9689 -b3 > 
cat9689.tub

Here, "/usr/bin/time ..." is the command I launched for the first
process, the second error message was quite similar, now for the second
process. The process started first ran about 6 minutes, the second about
14 minutes, so the TERM signals have been issued at different times (the
processes had been started within one minute). The two other processes
continued without problems. The point is that I did NOT issue a TERM
signal to the processes, I conclude that the OS issued the TERM signals.
The effect can be repeated to some extend: if another CPU-intensive
process is started (e.g. a lengthy compilation) then an already running
CPU-intensive process may be killed, if so then the one first started.

When the killed program had been relaunched with the same parameters but
without concurrency of other CPU-intensive processes (e.g. only editing,
reading e-mails running in parallel) then all things were fine, so the
kill is really not caused by the program. The program does not use
external devices and even no I/O except for writing a summary to stdout
at program end (i.e. not when the processes were killed).

The question is, why have the processes been killed? Is the OS unable to manage 
as many running processes? 
I consider this a bug in the OS, part process management. 
The bug implies that the computer can be used for light weight tasks only. 

With regards
Dr. Wolfgang Jansen

PS: 
Additional platform info (commands "ulimit -a", "top" when two CPU-intensive 
processes were still running): 

core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 30092
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 1024
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 30092
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

-----------------------------------------------

Tasks: 244 total,   3 running, 241 sleeping,   0 stopped,   0 zombie
%Cpu(s): 15.5 us,  1.2 sy, 27.5 ni, 54.6 id,  1.2 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem:   3930376 total,  2263872 used,  1666504 free,    36756 buffers
KiB Swap:     9212 total,     9212 used,        0 free,   705612 cached

  PID USER      PR  NI  VIRT  RES  SHR S P  %CPU %MEM   TIME COMMAND            
18804 wolfgang  30  10 14632  960  648 R 1 103.0  0.0  95:09 testu01long        
18817 wolfgang  30  10 14632  960  648 R 0 103.0  0.0  94:03 testu01long        
 2491 root      20   0  444m 128m 103m S 2   6.4  3.3   7:04 Xorg               
 2945 wolfgang  20   0 1950m 205m  11m S 2   6.4  5.4  13:08 cinnamon           
    1 root      20   0 27336 1536    0 S 1   0.0  0.0   0:01 init               
    2 root      20   0     0    0    0 S 3   0.0  0.0   0:00 kthreadd           
    3 root      20   0     0    0    0 S 0   0.0  0.0   0:00 ksoftirqd/0        
    5 root       0 -20     0    0    0 S 0   0.0  0.0   0:00 kworker/0:0H       
    7 root      rt   0     0    0    0 S 0   0.0  0.0   0:00 migration/0        
    8 root      20   0     0    0    0 S 0   0.0  0.0   0:00 rcu_bh             
    9 root      20   0     0    0    0 S 0   0.0  0.0   0:00 rcuob/0            
   10 root      20   0     0    0    0 S 0   0.0  0.0   0:00 rcuob/1            
   11 root      20   0     0    0    0 S 0   0.0  0.0   0:00 rcuob/2            
   12 root      20   0     0    0    0 S 0   0.0  0.0   0:00 rcuob/3            
   13 root      20   0     0    0    0 S 3   0.0  0.0   0:27 rcu_sched          
   14 root      20   0     0    0    0 S 3   0.0  0.0   0:06 rcuos/0            
   15 root      20   0     0    0    0 S 1   0.0  0.0   0:07 rcuos/1    
         
Remark: The critical figure seems to be the swap space.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: linux-image-3.11.0-19-generic 3.11.0-19.33
ProcVersionSignature: Ubuntu 3.11.0-19.33-generic 3.11.10.5
Uname: Linux 3.11.0-19-generic x86_64
ApportVersion: 2.12.5-0ubuntu2.2
Architecture: amd64
AudioDevicesInUse:
 USER        PID ACCESS COMMAND
 /dev/snd/controlC1:  wolfgang   2911 F.... pulseaudio
 /dev/snd/controlC0:  wolfgang   2911 F.... pulseaudio
CurrentDmesg: Error: command ['sh', '-c', 'dmesg | comm -13 --nocheck-order 
/var/log/dmesg -'] failed with exit code 1: comm: /var/log/dmesg: Permission 
denied
Date: Wed Apr 16 11:35:44 2014
InstallationDate: Installed on 2014-03-20 (26 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
IwConfig:
 eth0      no wireless extensions.
 
 lo        no wireless extensions.
MachineType: Acer Aspire XC600
MarkForUpload: True
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.11.0-19-generic 
root=UUID=10374065-1d70-4588-aca9-25093062a44a ro quiet splash vt.handoff=7
RfKill:
 
SourcePackage: linux
UpgradeStatus: Upgraded to saucy on 2014-03-21 (25 days ago)
WifiSyslog:
 
dmi.bios.date: 11/02/2012
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: P11-A3
dmi.board.name: Aspire XC600
dmi.board.vendor: Acer
dmi.board.version: v1.0
dmi.chassis.type: 3
dmi.chassis.vendor: Acer
dmi.modalias: 
dmi:bvnAmericanMegatrendsInc.:bvrP11-A3:bd11/02/2012:svnAcer:pnAspireXC600:pvr:rvnAcer:rnAspireXC600:rvrv1.0:cvnAcer:ct3:cvr:
dmi.product.name: Aspire XC600
dmi.sys.vendor: Acer

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug saucy

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https://bugs.launchpad.net/bugs/1308474

Title:
  CPU-intensive processes killed by OS

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