Very Computer

I noticed that randomly some messages are skipped (they are not present in
the log file though I am sure the programme has called the syslog() function
with correct parameters).
The syslog() function has no return code. I believed that it was because
there was no errors.

I read in the man pages that the syslogd daemon is reading in the /dev/log
device messages written by calls to syslogd(). Is it possible that this
device has a limited size and that when it is full, new messages are lost?

In that case, what can I do to make it works.

Basically, what I need is a mechanism that make it possible for several
multithreaded processes to write messages in a common file. I thought syslog
was a good solution. What do you think about that?
Is there a better solution?

--

Nate Eldredge

--
Drive^H^Hnk safely!
Alex Verstak                 averstak at vt dot edu
1078 Ambler Johnston East             *ia Tech
Blacksburg, VA 24060-0022       Tel. (540) 232-1389

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open("/dev/conslog", O_WRONLY)                  = 1
fcntl(1, F_SETFD, 0x00000001)                   = 0
fstat(1, 0xEFFFE340)                            = 0
fstat(1, 0xEFFFEDA0)                            = 0
time()                                          = 948262988
open("/usr/share/lib/zoneinfo/US/Pacific", O_RDONLY) = 3
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0".., 8192)     = 1000
close(3)                                        = 0
putmsg(1, 0xEFFFE458, 0xEFFFE44C, 0)            = 0
open("/etc/.syslog_door", O_RDONLY)             = 3
door_info(3, 0xEFFFE390)                        = 0
getpid()                                        = 6497 [6496]
door_call(3, 0xEFFFE378)                        = 0
close(3)                                        = 0

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 Alex> Syslog messages are sent to syslogd via datagrams (Unix domain
 Alex> or UDP).

Not on Solaris 2.6 they aren't - it uses the doors interface.

--
Andrew.

comp.unix.programmer FAQ: see <URL: http://www.erlenstar.demon.co.uk/unix/>
                           or <URL: http://www.whitefang.com/unix/>

 Arnaud> My programme under Solaris 2.6 logs information using the
 Arnaud> syslog function at the rate of about 100 messages/secondes.

Make sure you're up to date on patches - syslogd on 2.6 has been
pretty buggy.

--
Andrew.

comp.unix.programmer FAQ: see <URL: http://www.erlenstar.demon.co.uk/unix/>
                           or <URL: http://www.whitefang.com/unix/>

 Alex> Syslog messages are sent to syslogd via datagrams (Unix domain
 Alex> or UDP).

 >> Not on Solaris 2.6 they aren't - it uses the doors interface.

 Russ> My understanding is that it only uses doors to check to see if
 Russ> syslogd is running, and that the actual message is sent via a
 Russ> streams socket (/dev/log).  But I could be mistaken.

I think you are. This kind of local IPC is precisely what doors exist
for, there is no reason to involve sockets. (truss will show you the
details anyway.)

(If syslog() fails to open the door descriptor (/etc/.syslog_door IIRC),
it may well fall back to some other mechanism. One interesting issue I
found on 2.6 is that syslog() will spawn numerous child processes and
get thoroughly wedged if there are no free descriptors at the time of
the call - which is a pain. openlog() doesn't help with this, either -
it seems to insist on opening+closing the door descriptor on every call.)

--
Andrew.

comp.unix.programmer FAQ: see <URL: http://www.erlenstar.demon.co.uk/unix/>
                           or <URL: http://www.whitefang.com/unix/>