问题
I found this why multiple processes have the same object id in python, but I do not quite understand what does it mean "because both processes execute the same code", I try the code, it seems the outputs are always the same.
➜ ~ python test2.py
4419085696
4419085696
➜ ~ python test2.py
4342830464
4342830464
➜ ~ python test2.py
4510156160
4510156160
➜ ~ python test2.py
4329948544
4329948544
➜ ~ python test2.py
4468004224
4468004224
➜ ~ python test2.py
4326647168
4326647168
➜ ~ python test2.py
4445738368
4445738368
➜ ~ python test2.py
4388980096
4388980096
➜ ~ python test2.py
4511999360
4511999360
➜ ~ python test2.py
4562851200
4562851200
➜ ~ python test2.py
4535031168
4535031168
➜ ~ python test2.py
4314420608
4314420608
➜ ~ python test2.py
4536034688
4536034688
I also find this refer http://code.activestate.com/lists/python-list/656748/ on web. It also seems that python multiple processes shares the same object.
Anyone could help to explain a bit further? Thanks in advance.
回答1:
The id of an object in CPython is the objects memory address as seen by the process itself. The OS prevents different processes from seeing other processes memory.
Gross simplification warning As far as each process is concerned, its memory space starts at 0 and goes up. Two different processes that start up and ask for a 1000-byte block of memory from the OS will both think they have memory block 0-1000, but they are not actually sharing memory.
See https://en.wikipedia.org/wiki/Virtual_address_space for a good intro and better explanation.
来源：https://stackoverflow.com/questions/49977765/python-multiple-process-share-the-same-object-or-not