How useful can seed using MAC address + time be in system with multiple cores? Shouldn't it be CoreID + time? Just image you have 16 cores and just one MAC address. Is such an assumption valid to make?
You would need process/thread number + mac address + time
Hmm - the RFC 4122 doesn't tell anything about threads. Version 1 UUIDs are generated according to the following algorithm: o Determine the values for the UTC-based timestamp and clock sequence to be used in the UUID, as described in Section 4.2.1. o For the purposes of this algorithm, consider the timestamp to be a 60-bit unsigned integer and the clock sequence to be a 14-bit unsigned integer. Sequentially number the bits in a field, starting with zero for the least significant bit. o Set the time_low field equal to the least significant 32 bits (bits zero through 31) of the timestamp in the same order of significance. o Set the time_mid field equal to bits 32 through 47 from the timestamp in the same order of significance. o Set the 12 least significant bits (bits zero through 11) of the time_hi_and_version field equal to bits 48 through 59 from the timestamp in the same order of significance. o Set the four most significant bits (bits 12 through 15) of the time_hi_and_version field to the 4-bit version number corresponding to the UUID version being created, as shown in the table above. o Set the clock_seq_low field to the eight least significant bits (bits zero through 7) of the clock sequence in the same order of significance. o Set the 6 least significant bits (bits zero through 5) of the clock_seq_hi_and_reserved field to the 6 most significant bits (bits 8 through 13) of the clock sequence in the same order of significance. o Set the two most significant bits (bits 6 and 7) of the clock_seq_hi_and_reserved to zero and one, respectively. o Set the node field to the 48-bit IEEE address in the same order of significance as the address. Oliver