Strange CPU usage...

[G.S.-2]

Hello everyone,

Has anyone else had a problem where after running their Erlang node for some
distributed (multi process) program, their CPU (whether single, or dual, or
quad core), went into 100% use, even after you killed the node completely?

I've tried everything, but after a month of testing different stuff, the
only consistent part in this 100% cpu usage is that it occurs every once in
a while after I run my Erlang program, the thing that is strange is that
even after I kill the node, the cpu is still bogged down. The System Monitor
(Top), doesn't even show a process that uses 100% of the cpu, yet at the
same time shows the CPU as being in 100% use.

I can understand if my program goes into some infinite loop, but it persists
after the node is killed.

Any suggestions?
-Gene
p.s. I'm on linux, Debian.

[jm-13]

G.S. wrote:
> I've tried everything, but after a month of testing different stuff, the
> only consistent part in this 100% cpu usage is that it occurs every once in
> a while after I run my Erlang program, the thing that is strange is that
> even after I kill the node, the cpu is still bogged down. The System Monitor
> (Top), doesn't even show a process that uses 100% of the cpu, yet at the
> same time shows the CPU as being in 100% use.
>
>  

Strange. What's the breakdown of the CPU usage? is it user, wait, or
something else?

in top hit the "1" key this should break the usage down by CPU you
should see something similar to

top - 10:13:01 up 288 days, 12:32,  1 user,  load average: 0.00, 0.02, 0.06
Tasks:  88 total,   1 running,  87 sleeping,   0 stopped,   0 zombie
Cpu0  :  0.7%us,  0.0%sy,  0.0%ni, 99.3%id,  0.0%wa,  0.0%hi,  0.0%si,  
0.0%st    <--***
Cpu1  :  0.7%us,  0.3%sy,  0.0%ni, 98.7%id,  0.0%wa,  0.0%hi,  0.3%si,  
0.0%st    <--***
Mem:   3367504k total,  3224704k used,   142800k free,   149220k buffers
Swap:  2031608k total,       36k used,  2031572k free,  2744644k cached


Try a different kernel version. It could be a kernel or driver bug.

Jeff.


________________________________________________________________
erlang-questions mailing list. See http://www.erlang.org/faq.html
erlang-questions (at) erlang.org

[Richard Andrews-5]

On Fri, Jul 3, 2009 at 10:01 AM, G.S.<corticalcomputer@...> wrote:

> Hello everyone,
>
> Has anyone else had a problem where after running their Erlang node for some
> distributed (multi process) program, their CPU (whether single, or dual, or
> quad core), went into 100% use, even after you killed the node completely?
>
> I've tried everything, but after a month of testing different stuff, the
> only consistent part in this 100% cpu usage is that it occurs every once in
> a while after I run my Erlang program, the thing that is strange is that
> even after I kill the node, the cpu is still bogged down. The System Monitor
> (Top), doesn't even show a process that uses 100% of the cpu, yet at the
> same time shows the CPU as being in 100% use.
>
> I can understand if my program goes into some infinite loop, but it persists
> after the node is killed.
>
> Any suggestions?
> -Gene
> p.s. I'm on linux, Debian.
>

If it is not attributed to a process in top then it will probably be
iowait on a disk. Are you running a database or other software that
might do large writes to disk from time to time?

________________________________________________________________
erlang-questions mailing list. See http://www.erlang.org/faq.html
erlang-questions (at) erlang.org