WAITPID WNOHANG hangs

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Well. My application calls posix_spawn to: launch a bash file which in turn: calls make & compiles my program.

The code has been working for years.

Now it doesn't. ( Fedora 24 latest updates )

It hangs on the wait. The forked process does not end. All the forked process does is launch a background process and exit immediately.

int waitPIDerr= waitpid( pid, NULL, 0 /* WNOHANG */ );

I'm thinking to simply wait on a loop then kill the pid. Which will work. But isn't right.

Any ideas as to why this code that has been working 100% reliable for years no longer works are welcome. To be fair. I use Linux. I'm no way any sort of expert on its many complexities.

However. This would appear to be an issue with OS upgrades.