[Feature] Support for running jobs in child processes

[Manuel Astudillo]

Many times, processes are long and synchronous. Currently design does not allow to run these kind of processes properly due to the locking mechanism. However, we can spawn a child process where the job is run instead. If the same child process is reused for every job (and we will need as many child processes as concurrency levels), the overhead will be minimum. Also as an added benefit, if the child process dies for any reason (memory leaks, or other cause), the worker will still be able to spawn a child replacement and continue working normally.