Hello,

I'm trying to get help on some problems I'm facing using Firebird DB engine on a Linux SMP server.

Firebird is installed on a linux server like this

Linux 3.5.2-030502-generic #201208151151 SMP Wed Aug 15 15:52:12 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

with 8 cpu on a VmWare ESXi 4.1 host.

In general I compile myself Firebird from sources, which I download here
http://web.firebirdsql.org/download/snapshot_builds/linux/fb2.5/

I use this to compile
CFLAGS=-march=native ./configure --prefix=/opt/fb25ss --with-system-editline --with-system-icu

Since I saw something stranhe related to memory usage, two days ago
I compiled this sources
http://web.firebirdsql.org/download/snapshot_builds/linux/fb2.5/Firebird-2.5.2.26527-0.tar.bz2

with debug activated like this

CFLAGS=-march=native ./configure --prefix=/opt/fb25ss --enable-debug --with-system-editline --with-system-icu

I'm using SuperClassic configuration using this command after compiling/installing

/opt/fb25ss/bin/changeMultiConnectMode.sh ---> thread

Linux server has 8G RAM and 36GB swap space.

The strange thing I noticed is that after some time after starting DB engine, VM committer memory used by Firebird is going very very high
ans always increasing... after 8 hours for example typically is like this

PID RUID EUID THR SYSCPU USRCPU VGROW RGROW RDDSK WRDSK ST EXC S CPUNR CPU CMD 1/1
7502 firebird firebird 10 13m08s 82m34s 40.8G 2.2G 11.1G 3.7G N- - S 0 9% fb_smp_server

with something 40G of committed virtual memory... so huge? and always
increasing?

but not all RAM is used
MEM | tot 7.7G | free 3.2G | cache 2.4G | dirty 0.1M | buff 0.0M | slab 206.3M
and not swap space used
SWP | tot 32.0G | free 32.0G |

So why Linux kernel was reporting about 40G of virt ram used by Firebird?

When started virtual memory is lower

16761 firebird firebird 9 7.89s 26.90s 5.3G 204.0M 363.0M 20528K N- - S 0 0% fb_smp_server

about 5G.


fb_smp_server is running typically in 10 thread, connected to DB
like this

Database "/var/lib/firebird/2.5/data/h3o.estsesia.fdb"
Database header page information:
Flags 0
Checksum 12345
Generation 434005
Page size 16384
ODS version 11.2
Oldest transaction 346399
Oldest active 346400
Oldest snapshot 346400
Next transaction 346401
Bumped transaction 1
Sequence number 0
Next attachment ID 87298
Implementation ID 24
Shadow count 0
Page buffers 18000
Next header page 0
Clumplet End 102
Database dialect 3
Creation date May 10, 2012 8:48:24
Attributes force write

Variable header data:
Sweep interval: 0
*END*


Further, After installing debug version, I saw in log messages like this

root@h3oserver-DB:/home/corrtek# tail -f /opt/fb25ss/firebird.log
wait_for_request: owner 32752 reposted 550 times for lock 30248


h3oserver-DB Fri Aug 24 07:49:36 2012
wait_for_request: owner 32752 reposted 600 times for lock 30248


h3oserver-DB Fri Aug 24 08:04:54 2012
wait_for_request: owner 32752 reposted 50 times for lock 30248

What's that?

Please, someone can help me to figure out why FB is using so much virtual committed memory and what are those log messages?

Many thanks.

Best regards.