1

Here's the top output:

top - 19:20:47 up 1 day,  4:30,  1 user,  load average: 0.01, 0.07, 0.12
Tasks: 170 total,   1 running, 169 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.6 us,  0.9 sy,  0.0 ni, 95.4 id,  0.1 wa,  0.0 hi,  0.0 si,  3.0 st
KiB Mem:   8167220 total,  7878764 used,   288456 free,   296816 buffers
KiB Swap:  1952764 total,    12672 used,  1940092 free,  1671708 cached

  PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND
 2799 app0005   20   0 1565m 866m  11m S 106.6 10.9   1718:03 java

How is it possible that one process is running at 100% CPU for many hours, but the system load is still near 0.0?

OS is Debian Wheezy, VM is running on a Citrix XenServer, using 4 Cores.

Here is the output of pidstat -p 2799 -t 5 3 (many rows with 0.00 values omitted):

Linux 3.2.0-4-amd64 (s1018)     08/04/2015      _x86_64_        (4 CPU)

05:33:33 AM      TGID       TID    %usr %system  %guest    %CPU   CPU  Command
05:33:38 AM      2799         -   75.65   35.53    0.00  111.18     2  java
05:33:38 AM         -      2799    0.00    0.00    0.00    0.00     2  |__java
05:33:38 AM         -      2836   23.95   33.93    0.00   57.88     1  |__java
05:33:38 AM         -      3291   33.33   12.77    0.00   46.11     1  |__java

05:33:38 AM      TGID       TID    %usr %system  %guest    %CPU   CPU  Command
05:33:43 AM      2799         -   29.60   77.80    0.00  107.40     2  java
05:33:43 AM         -      2836   17.00   41.40    0.00   58.40     0  |__java
05:33:43 AM         -      3291   10.60   36.80    0.00   47.40     1  |__java

05:33:43 AM      TGID       TID    %usr %system  %guest    %CPU   CPU  Command
05:33:48 AM      2799         -   40.40   66.80    0.00  107.20     2  java
05:33:48 AM         -      2836   21.60   37.00    0.00   58.60     1  |__java
05:33:48 AM         -      3291   13.20   34.60    0.00   47.80     0  |__java

Average:         TGID       TID    %usr %system  %guest    %CPU   CPU  Command
Average:         2799         -   48.57   60.03    0.00  108.59     -  java
Average:            -      2799    0.00    0.00    0.00    0.00     -  |__java
Average:            -      2836   20.85   37.44    0.00   58.29     -  |__java
Average:            -      3291   19.05   28.05    0.00   47.10     -  |__java
6
  • 3
    How many CPUs do you have? Aug 3, 2015 at 17:30
  • 2
    @ott-- Attaching strace to a CPU bound process may produce no output. A CPU bound process might simply not make any system calls.
    – kasperd
    Aug 3, 2015 at 18:37
  • Please show the results of pidstat -t -G java 5 3 Aug 3, 2015 at 18:37
  • @matthew I have added the requested output.
    – nn4l
    Aug 4, 2015 at 3:48
  • use vmstat to check if you have process in runqueue or in blocking state, the loadaverage goes high in that conditions, if your system has many process waiting to be running or you have many process waiting for IO.
    – c4f4t0r
    Aug 4, 2015 at 4:45

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