[valray]

If I understand this correctly, the algorithm depends on the underlying platform to ensure correct ordering. Two processes may each get the same bakery ticket number. The conflict is resolved by the process with the lower process id being allowed to go first. This process ID is in effect a ticket number issued by the underlying hardware. If the processes were running in a distributed environment, there would not be a common underlying platform to resolve this conflict.

[eigenvalue]

In that context you could simply pick another thing as the tie breaker, like the IP address expressed as an integer (ie, remove the periods and treat like a number) being lower.

[valray]

Ah, yes, that would work.

But then there is reliance on an underlying platform to resolve the conflict by providing a globally unique identifier. Instead of process ID, there is the IP address mechanism.

So it's turtles all the way down, if I understand correctly.

[eigenvalue]

Not really. Each process could, at the beginning, generate a random nonce and broadcast it and thereafter use that as its tiebreaker number. The point is to just have a consistent way to break ties that is convenient to implement in whatever domain you’re working in. And in a networked domain, without a valid IP address, the worker isn’t going to be doing much in the process anyway since it wouldn’t be able to communicate at all.

[somat]

But it's not in a distributed environment, it is a shared memory environment. That is the whole point. If it were a distributed environment the processes would not have to worry about smashing each others memory because they would not share memory in the first place.

[Dylan16807]

Most shared memory environments are distributed, at least to some extent. The process ID is not an issue, you can do the equivalent in a distributed environment just fine. But the algorithm depends on strict memory ordering, and that's much harder to provide than atomic writes. Most shared memory systems don't offer it.