[issue36408] Tkinter multi-processing performance, Linux 10-25 times faster than Windows 10
New submission from J.E.McCormack : I am measuring multi-process GUI performance (Tkinter 8.6, Python 3.7) for drawing lines, circles, text boxes, etc. In a fairly typical experiment on a i7-6700HQ, 4-core (8 thread), on Windows 10 I measure 25.5k objects/sec for one process running alone, and 19.9k objects/sec total for eight processes. For Linux Kubuntu KDE desktop the figures are 61k objects/sec and 230k objects/sec (a multi-core boost of times 3.8). For running eight processes, the performance difference, KDE vs Win10, is therefore times 11.6. The difference over a range of tests is 10-25 times. Clearly Win10 is not doing multi-core. Perhaps Tkinter is calling a Windows SDK function which is not thread-safe within the Windows GDI, imposing a single-thread barrier system-wide? I am just wondering, firstly, if I have simply missed mention of this limitation anywhere. I can supply more info if needed. -- components: Tkinter messages: 338682 nosy: james.mccormack priority: normal severity: normal status: open title: Tkinter multi-processing performance, Linux 10-25 times faster than Windows 10 type: performance versions: Python 3.7 ___ Python tracker <https://bugs.python.org/issue36408> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue36408] Tkinter multi-processing performance, Linux 10-25 times faster than Windows 10
J.E.McCormack added the comment: I can run four independent processes (i.e. not using multiprocessing, with no links at all between them) yet the results show that only one core is running. Where is this lock taking place? Why would a tkinter process need to know about another tkinter process? A little bit of history I have learned is that prior to Windows 7, the GDI sub-system imposed a global lock system-wide so that only one process (one thread) could write to the display at one time. This meant in effect it was a one-core GUI desktop. From Windows 7, this was supposed to have been 'fixed', but all I have read is that the "GDI lock became more fine-grained, reducing concurrency bottlenecks". I wonder did anyone ever measure performance in real-world scenarios to demonstrate whether there was in fact any improvement? -- ___ Python tracker <https://bugs.python.org/issue36408> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue36408] Tkinter multi-processing performance, Linux 10-25 times faster than Windows 10
J.E.McCormack added the comment: Attached is a minimal reproducer script which is sufficient to show the issue clearly. It is a simple single-thread Tkinter program with one canvas. No multiprocessing, no shared variables, no connections between instances. Instructions at top of file. Results on i7-6700HQ, 4-core (8 thread), 2.60GHz, 16GB, Windows 10:- 1 process running alone: 29k objects/sec 6 processes running concurrently:4.3k objects/sec each, = 25.8k objects/sec combined. Conclusion: One-core performance, global system-wide lock. -- Added file: https://bugs.python.org/file48232/mosaic.py ___ Python tracker <https://bugs.python.org/issue36408> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
