Comment 13 for bug 1672819

exec'ing from a thread is an interesting problem; the semantics of exec should be to terminal all the threads before the exec occurs according to http://maxim.int.ru/bookshelf/PthreadsProgram/htm/r_44.html

The normal idiom would be to do:
  fork()
      child exec's
      parent waits for child

I'm not sure in your case if you desire all the threads to terminate after the exec, so the wait() may be in fact be replaced by pthread termination calls on all the threads for your implementation.

Unfortunately there is an issue with fork'ing in a thread; any mutex held by another thread at the moment of fork becomes locked forever since we have once mutex locked by the parent and one by the child. Normally one would therefore use pthread_atfork() to help workaround this issue, see https://stackoverflow.com/questions/14407544/mixing-threads-fork-and-mutexes-what-should-i-watch-out-for