René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Qt Ctrl-C broken on windows","articleBody":"@anntzer @tacaswell \r\nHi! I have just tested the master branch on Windows and found that there is indeed a problem with the QSocketNotifier (it appeared here: https://github.com/matplotlib/matplotlib/pull/13306#issuecomment-760878434). Previously, on that Windows machine, I was running my old code with QAbstractSocket which was fine, and did not test the newest version with QSocketNotifier there (my fault, sorry). I have tested on Linux, and there is no such problem there.\r\n\r\nThe code to reproduce on Windows (in Jupyter):\r\n```python\r\n%matplotlib qt\r\nfrom matplotlib import pyplot as plt\r\nplt.plot([1,2])\r\nplt.pause(.1)\r\nplt.pause(.1)\r\nplt.pause(.1)\r\n```\r\nThe problem seems to be that if `socketpair` generates a socket with the same `fileno` value as it generated in the previous `pause()` call, the QSocketNotifier _unexpectedly_ fires and hangs here: https://github.com/matplotlib/matplotlib/blob/b600026fe86bf0c7e14fc56f568b8b1fae07313d/lib/matplotlib/backends/qt_compat.py#L232\r\nbecause _nothing was actually written_ to the `wakeup_fd`. I don't understand how that can be.\r\n\r\nWorkaround fix:\r\n```python\r\nrsock.set_blocking(False)\r\n\r\n@sn.activated.connect\r\ndef on_signal(*args):\r\n    try:\r\n        signal = rsock.recv(1)  # clear the socket to re-arm the notifier\r\n    except BlockingIOError:\r\n        pass # false-trigger, nothing on rsock\r\n```\r\n\r\nWhat should we do with this? Is there a better solution?\r\n\r\n_Originally posted by @vdrhtc in https://github.com/matplotlib/matplotlib/issues/13306#issuecomment-906467433_","author":{"url":"https://github.com/tacaswell","@type":"Person","name":"tacaswell"},"datePublished":"2021-08-28T18:47:42.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":9},"url":"https://github.com/20932/matplotlib/issues/20932"}