Edit: fail_switch_three_greenlets.py
""" Uses a trace function to switch greenlets at unexpected times. In the trace function, we switch from the current greenlet to another greenlet, which switches """ import greenlet g1 = None g2 = None switch_to_g2 = False def tracefunc(*args): print('TRACE', *args) global switch_to_g2 if switch_to_g2: switch_to_g2 = False g2.switch() print('\tLEAVE TRACE', *args) def g1_run(): print('In g1_run') global switch_to_g2 switch_to_g2 = True from_parent = greenlet.getcurrent().parent.switch() print('Return to g1_run') print('From parent', from_parent) def g2_run(): #g1.switch() greenlet.getcurrent().parent.switch() greenlet.settrace(tracefunc) g1 = greenlet.greenlet(g1_run) g2 = greenlet.greenlet(g2_run) # This switch didn't actually finish! # And if it did, it would raise TypeError # because g1_run() doesn't take any arguments. g1.switch(1) print('Back in main') g1.switch(2)
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