Forum OpenACS Q&A: Response to What are all the fields that Aolserver includes in the log?

From aolserver/nsd/log.c:
Log(Ns_LogSeverity severity, char *fmt, va_list *argsPtr)
    . . .
    fprintf(fp, "%s[%d.%d][%s] %s: ", timebuf,
		Ns_InfoPid(), Ns_ThreadId(), Ns_ThreadGetName(), severityStr);
The third field is the thread id. The fourth is more functional. For connections it will be the connection number, but it can be all sorts of things, including -main-, -sched-, -socks-, and -thread<n>-.