[ClusterLabs] Antw: crm_report consumes all available RAM

[Ulrich Windl]

>>> Vladislav Bogdanov <bubble at hoster-ok.com> schrieb am 08.09.2015 um 14:05 in
Nachricht <55EECEFB.8050001 at hoster-ok.com>:
> Hi,
> 
> just discovered very interesting issue.
> If there is a system user with very big UID (80000002 in my case),
> then crm_report (actually 'grep' it runs) consumes too much RAM.
> 
> Relevant part of the process tree at that moment looks like (word-wrap off):
> USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
> ...
> root     25526  0.0  0.0 106364   636 ?        S    12:37   0:00          \_ 
> /bin/sh /usr/sbin/crm_report --dest=/var/log/crm_report -f 0000-01-01 00:00:00
> root     25585  0.0  0.0 106364   636 ?        S    12:37   0:00             
>  \_ bash /var/log/crm_report/collector
> root     25613  0.0  0.0 106364   152 ?        S    12:37   0:00             
>      \_ bash /var/log/crm_report/collector
> root     25614  0.0  0.0 106364   692 ?        S    12:37   0:00             
>          \_ bash /var/log/crm_report/collector
> root     27965  4.9  0.0 100936   452 ?        S    12:38   0:01             
>          |   \_ cat /var/log/lastlog
> root     27966 23.0 82.9 3248996 1594688 ?     D    12:38   0:08             
>          |   \_ grep -l -e Starting Pacemaker
> root     25615  0.0  0.0 155432   600 ?        S    12:37   0:00             
>          \_ sort -u
> 
> ls -ls /var/log/lastlog shows:
> 40 -rw-r--r--. 1 root root 23360000876 Sep  8 04:36 /var/log/lastlog
> 
> That is sparse binary file, which consumes only 40k of disk space.
> At the same time its size is 23GB, and grep takes all the RAM trying to
> grep a string from a 23GB of mostly zeroes without new-lines.
> 
> I believe this is worth fixing,

I guess the UID value is used as offset in the lastlog file (which is OK). When reading such a sparse file, the filesystem should simply deliver zero blocks to grep. As grep is designed to read from streads there is not much you can do against reading all these zeros, I guess. Also an mmap based solution might exceed the virtual address space, especially for 32-bit systems.
BTW: Did you try "last Pacemaker"? I could only test with "last reboot" here...

Regards,
Ulrich

> 
> Thank you,
> Vladislav
> 
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