Hi,

We came across a problem were when using Poco::Process::launch on a MacOS BigSur, this creates processes that takes 100% of the cpu core their running on.

In Process_UNIX.cpp l122 we have this for:
for (int i = 3; i < sysconf(_SC_OPEN_MAX); ++i)

It seems that sysconf(_SC_OPEN_MAX) is slow and return a very big value on this new OS, it's evaluated on each loop of the for so it takes ages and a lot of CPU to run.

This thread reports the same problem: warmcat/libwebsockets#2116