[syslog-ng]HUP'ing syslog-ng causes data loss

[UK]

Greetings,

Trying to see what happens when syslog-ng (Version 1.4.14 on Solaris 8) gets
HUP'ed, as my logrotate scripts will do, while it's receiving UDP data.
Using the stresstes.sh script on another host (which is using the syslog-ng
box as a loghost), a stream of messages will be sent. The while loop was
changed to:

 while [ "$i" -lt "1000" ]

After the script ran, a "cat messages | wc -l" was done against the log and
the results would be approx 995 lines (probably because it's UDP). Then I'd
move the file and HUP syslog-ng and retested a few more times. Same results
each time.

Next, while stresstest.sh was running, syslog-ng would be HUP'ed two or
three times. After every test the "cat messages | wc -l" would show between
965 - 975 lines.

My questions: How can I prevent messages from being lost when syslog-ng gets
HUP'ed? Is it due to a config file error? From reading archived logs I found
this wouldn't happen with TCP but I didn't see any information about UDP.

My config file:
------------
options {
        sync(0);
        create_dirs(yes);
        use_fqdn(yes);
        keep_hostname(yes);
        };

source src {
      sun-streams("/dev/log"
      door("/etc/.syslog_door"));
      udp();
      internal();
      };

destination d_cisco {
     file("/opt/logs/cisco.log"); };

destination d_other {
     file("/var/log/syslog-ng/$HOST/messages"
       sync(0) create_dirs(yes)); };

destination d_adm {
     file("/var/log/syslog-ng/$HOST/sysmsg"
       sync(0) create_dirs(yes)); };

filter f_cisco {
     facility(local4); };

# stuff that would go into /var/log/messages

filter f_messages {
     level(info..warn)
     and not facility(auth, auth, mail, news, local4);
     };

filter f_daemonlog {
     facility(daemon) and
     level (info,warn,notice,err,crit,alert,emerg);
     };

log { source(src);
     filter(f_cisco);
     destination(d_cisco); };

log { source(src);
     filter(f_messages);
     destination(d_other); };

log { source(src);
     filter(f_daemonlog);
     destination(d_adm);  };
------------

Thanks,

UK