z3 trace-file-name

[pieter-bos]

Could you perhaps set a different trace-file-name for z3 instances when proof and/or trace are enabled?

In case you were curious about context, we encountered a problem when we set a unix pipe as the trace file name, which enables us to inspect the progress of z3 while it is running. If I am not mistaken even with --numberOfParallelVerifiers 1 two z3 processes are started, so they both wrote to this pipe until I made them have a different trace-file-name. I would guess that for regular files opened for writing the processes simply race to open the file.