Spread daemon -8 and -11 errors

Hi,
I'm running mod_log_spread with apache 2.0.47, using the prefork MPM, 
and spread 3.17.1. There is a spread daemon running locally on each web 
server, specified with the following line in httpd.conf:

SpreadDaemon 3333

Most (75%?) of the apache log messages are being sent over the spread 
ring and are recorded by spreadlogd on my logging host. However, portion 
of the log messages cause an error, and are not succesfully sent to the 
spread daemon. The errors look like this in the apache error log:

[Mon Dec 22 14:24:42 2003] [crit] [client 66.193.5.50] Spread Daemon 
returned an error. -11 This Request could not be logged 
/author/upload/upload_progress.cgi

There are also occasional -8 spread errors. Looking at sp.h in the 
spread source tells me that these errors are CONNECTION_CLOSED (-8) and 
ILLEGAL_SESSION (-11). These errors are returned a dozen different 
places in the spread daemon code, and I wasn't able to tell why in most 
cases.

READMEs, Google, and mailing list archives have not turned up anything 
useful. I tried linking mod_log_spread.so against libtspread, thinking 
it might be a problem with thread safety (don't think it should be, with 
the apache prefork MPM), but the same symptoms are present. Could this 
be a message length problem? I don't have any absurdly long URL's I'm 
servering up, and I'm using the standard "combined" log format. Probably 
no measureable percentage of log messages longer than 300 characters, 
except that I'm losing a large fraction of the log messages.

Also, I see the same symptoms on a web server that is under a heavy load 
(~10 log messages/sec) and another that has no load (just me testing). I 
see no pattern to the failures on the server under heavy load, but I can 
hit certain pages that will always generate a spread error on the test 
server.

Anyone ever seen something like this? TIA for your help.

Best Regards,
Bill Montgomery