I've seen a couple of questions on the topic but I didn't get a full answer...
My code is basically:
from multiprocessing import Process
p = Process(target=f).start()
p.join()
def f():
print 'break!'
And I want to put a breakpoint on the print. I'm using pydev+eclipse (on Ubuntu).
Because the new process itself is not controlled by PyDev, you need to make PyDev debugger manually aware of through Remote Debugging facilities.
http://pydev.org/manual_adv_remote_debugger.html
Use pydevd.set_trace() - notice that your breakpoints won't work (not sure if this has changed recent PyDev versions), but you need to manually enter set_trace() command to your code.
settrace() and not set_trace() and I had to set the port manually (i.e., pydevd.settrace(port=xx)). Other than that, it works great, thanks!