[syslog-ng] load failures in afsocket and afsql

Martin Holste mcholste at gmail.com
Fri Dec 17 06:26:07 CET 2010 

Congrats!  Go do some gambling because your karma has to be extremely
positive at this point!

On Thu, Dec 16, 2010 at 10:32 PM, Matthew Hall <mhall at mhcomputing.net> wrote:
> I think this patch might well fix it.
>
> I tried it with the patch just now and it seemed to launch OK.
>
> Matthew.
>
> On Thu, Dec 16, 2010 at 08:20:44PM -0800, Matthew Hall wrote:
>> Untested patch:
>>
>> --- /home/megahall/dbparser.c 2010-12-16 20:07:03.000000000 -0800
>> +++ syslog-ng-3.2.1/modules/dbparser/dbparser.c       2010-12-16 20:14:59.000000000 -0800
>> @@ -140,6 +140,11 @@
>>    else
>>      {
>>        log_db_parser_reload_database(self);
>> +      /* XXX: mhall: repair corruption of persistent config */
>> +      if (self->db)
>> +        {
>> +          cfg_persist_config_add(cfg, log_db_parser_format_persist_name(self), self->db, (GDestroyNotify) pattern_db_free, FALSE);
>> +        }
>>      }
>>
>>    self->timer_tick_id = g_timeout_add_seconds(1, log_db_parser_timer_tick, self);
>>
>> Matthew.
>>
>> On Thu, Dec 16, 2010 at 08:06:43PM -0800, Matthew Hall wrote:
>> > On Thu, Dec 16, 2010 at 04:55:09PM -0600, Martin Holste wrote:
>> > > Keep fighting the good fight, hopefully you'll get some hints soon.
>> > > You're well outside the range of my debugging-fu at this point.
>> > >
>> > > On Thu, Dec 16, 2010 at 3:34 PM, Matthew Hall <mhall at mhcomputing.net> wrote:
>> > > > Getting closer.
>> > > >
>> > > > The problem goes away when the XML pattern DB is disabled. The problem
>> > > > does not appear if the XML pattern db is used in one log {} per below.
>> > > > Once it is used in two log {} blocks, KABOOM! I'm going to try debugging
>> > > > the other half of this which writes to the persistent store to see if I
>> > > > can sort out what's breaking the write. For what it's worth, the problem
>> > > > shows up in both 32 and 64 bit.
>> > > >
>> > > > Matthew.
>> >
>> > I think the problem could be found now. In the log_db_parser_deinit,
>> > there is a call to cfg_persist_config_add but there is no corresponding
>> > call in log_db_parser_init.
>> >
>> > When the db_parser is referenced once in the config file, self->db is
>> > NULL, so log_db_parser_reload_database is called to create the right
>> > data structure. It's important to remember that this is going to set
>> > self->db_file_inode and self->db_file_mtime.
>> >
>> > When the db_parser is referenced again in the config file, self->db
>> > should be non NULL because the db_parser was supposed to be persisted.
>> >
>> > Bug 1) When we call cfg_persist_config_fetch but we get NULL again so we
>> > call log_db_parser_reload_database again.
>> >
>> > Bug 2) (Unrelated to my issue) Even if we had stored the db_parser, if
>> > we call stat, we just copy the new inode and mtime, and do not reload
>> > the patterns. So configuration reloads will probably not refresh the
>> > pattern DB.
>> >
>> > Now in my case when we go into log_db_parser_reload_database the second
>> > time, we have a check if the DB file exists. If no we have an error.
>> > Fair enough. But if yes, then we check if self->db_file_inode and
>> > self->sb_file_mtime have changed, or not.
>> >
>> > If they have not changed, we return right away, without initializing the
>> > self->db. But we have already destroyed the valid self->db pointer from
>> > the first initialization, by replacing it with the retval from
>> > cfg_persist_config_fetch, which was NULL because the config was not
>> > persisted.
>> >
>> > Now we check self->db again at the end of log_db_parser_init where we
>> > find it has become NULL. This we return a failing retval because we
>> > never suceeded in initializing the log_db_parser to a non-NULL value.
>> >
>> > We pass this error many frames up the stack until we hit the "Error
>> > initializing message pipeline" in log_center_init.
>> >
>> > This goes a few frames up, until we exit with an error code.
>> >
>> > I think the patch would be adding code to log_db_parser_init and/or
>> > log_db_parser_reload_database, which calls cfg_persist_config_add. I am
>> > going to try this Monday since I'm off tomorrow and see what I get.
>> >
>> > Could somebody else try making a config which references the EXACT SAME
>> > patterndb file twice in two log {} blocks and see if it blows up for
>> > them as well? I want to try to eliminate as many environment specific
>> > issues as possible. I described the config you need in my previous mail.
>> >
>> > Regards,
>> > Matthew.
>> >
>> > static gboolean log_db_parser_init(LogParser *s, GlobalConfig *cfg)
>> > {
>> >   LogDBParser *self = (LogDBParser *) s;
>> >
>> >   self->db = cfg_persist_config_fetch(cfg, ***log_db_parser_format_persist_name***(self));
>> >   if (self->db)
>> >     {
>> >       struct stat st;
>> >
>> >       if (stat(self->db_file, &st) < 0)
>> >         {
>> >           msg_error("Error stating pattern database file, no automatic reload will be performed",
>> >                     evt_tag_str("error", g_strerror(errno)),
>> >                     NULL);
>> >         }
>> >       else
>> >         {
>> >           self->db_file_inode = st.st_ino;
>> >           self->db_file_mtime = st.st_mtime;
>> >         }
>> >     }
>> >   else
>> >     {
>> >       log_db_parser_reload_database(self);
>> >     }
>> >
>> >   self->timer_tick_id = g_timeout_add_seconds(1, log_db_parser_timer_tick, self);
>> >   return self->db != NULL;
>> > }
>> >
>> > ______________________________________________________________________________
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>> >
>> ______________________________________________________________________________
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>> Documentation: http://www.balabit.com/support/documentation/?product=syslog-ng
>> FAQ: http://www.campin.net/syslog-ng/faq.html
>>
> ______________________________________________________________________________
> Member info: https://lists.balabit.hu/mailman/listinfo/syslog-ng
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> FAQ: http://www.campin.net/syslog-ng/faq.html
>
>

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