[syslog-ng] log failback groups

Patrick H. syslogng at feystorm.net
Fri Mar 19 01:49:38 CET 2010

We turned on syslog-ng for our production environment today and ran into 
a problem which I think the solution might also solve this one.
The problem I ran into is that with full production logging on, 
syslog-ng is using up about 50% of the CPU, and thats writing everything 
out to /dev/null (a few hundred machines). With a single regex turned 
on, it was using 90% CPU. So what I'm going to end up doing is running 
multiple syslog-ng processes so they can run in parallel on separate CPU 
cores. This way they can process data simultaneously. There will be a 
master process which basically sends everthing with the mail facility to 
two other syslog-ng processes, one of which will be parsing out data to 
insert into a database, and another will be parsing out data to write to 
files (different regexes for each).

Now, the way this might also solve the failover issue is to make 
multi-process capability part of syslog-ng. So one might end up with a 
config like:

@version: 3.0
options {

source s_sys {
source s_net {
    tcp(ip( port(514) max-connections(1000));
    udp(ip( port(514));
filter f_mail { facility(mail); };
process p_msgid {
    filter f_msgid {
        message('MsgID: (?<MESSAGEID>\S+)', type('pcre') 
    destination d_oracle { sql(...); };
    destination d_oracle_fallback { sql(...); };
    log { filter(f_msgid); destination(d_oracle); };
    log { filter(f_msgid); destination(d_oracle_fallback); 
flags(fallback); };
process p_foobar {
    options {
    filter f_foobar { ... };
    destination d_foobar { ... };
    destination d_foobar_fallback { ... };
    log { filter(f_foobar); destination(d_foobar); };
    log { filter(f_foobar); destination(d_foobar_fallback); 
flags(fallback); };

log { source(s_sys); source(s_net); filter(f_mail); 
destination(p_msgid); destination(p_foobar); };

This will launch 3 processes, a master control process that does very 
basic filtering and uses some sort of IPC to send the data to 2 other 
processes which inherit the global options section and accept every 
config statement the master process does except sources. This way each 
process can run in parallel on the different CPU cores, and can have 
fallback destinations that wont interfere with the other processes.

Sent: Wednesday, March 17, 2010 7:54:42 AM
From: Zoltán Pallagi <pzolee at balabit.hu>
To: Syslog-ng users' and developers' mailing list 
<syslog-ng at lists.balabit.hu>, syslogng at feystorm.net
Subject: Re: [syslog-ng] log failback groups
> Hi Patrick,
> As far as I know,  we would like to solve the failover/failback 
> problem in syslog-ng PE v3.2 (and perhaps in OSE v3.2), but we are 
> still working on it.
> However, we are planning to support it only in case of tcp/syslog 
> destinations.
> Patrick H. wrote:
>> How do you do groups of failbacks? For example
>> log { filter(f_filter1); destination(d_file1); };
>> log { filter(f_filter1); destination(d_file2); }; <-- log here only 
>> if the above fails
>> log { filter(f_filter2); destination(d_sql1); }; <-- may include 
>> messages from the above 2 lines
>> log { filter(f_filter2); destination(d_sql2); }; <-- log here only if 
>> d_sql1 fails
>> So, say lines 1 and 3 both fail, lines 2 and 3 should both start 
>> working. If I put a fallback flag on d_file2 and d_sql2, and d_sql1 
>> fails, d_sql2 wont kick in on matches that d_file1 is still taking.
>> It seems like there should be a way to do "log { destination(...) or 
>> destination(...); };", or "log {...} or log {...};".
>> ------------------------------------------------------------------------
>> ______________________________________________________________________________
>> Member info: https://lists.balabit.hu/mailman/listinfo/syslog-ng
>> Documentation: http://www.balabit.com/support/documentation/?product=syslog-ng
>> FAQ: http://www.campin.net/syslog-ng/faq.html
> -- 
> pzolee
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