[eesmith]

Yes, certainly. The paper covers many of those limitations.

The goal is not "remove", but "seek to remove". The relevant definition of "seek" here is "to make an attempt" says https://www.merriam-webster.com/dictionary/seek .

How many of those 1304 Ubuntu packages require fork()? Are there benefits to replacing (say) 1283 of them with posix_spawn()?

[sanxiyn]

Yes, there are benefits to using posix_spawn: It's faster. See Figure 1.

[eesmith]

How many of those packages would be improved with a faster spawn mechanism? Who is going to investigate each one? How will they convince upstream to change well-tested code?