The log whoformat option indicates the format of the log entry portion that prints which client application logged the entry.
The value of <log whoformat=""> is a character string that can contain substitution specifiers such as %p for process ID, %t for thread ID, etc.
The default value is <log whoformat="%08Xt>. This prints the thread ID ("%t") in uppercase hexadecimal format ("%Xt") with an 8 digits fixed width ("%8Xt") left-padded with zeroes (0) instead of spaces ("%08Xt") followed by a literal "> " as separator ("%08Xt> ").