For years, I've noticed that when resuming a laptop from sleep, kglobalaccel and X11 use 100% CPU for a few minutes, making everything crawl for a while.
I finally debugged why: kglobalaccel grabs and ungrabs all global shortcuts many many times in a row. KGlobalAccelImpl::nativeEventFilter event->response_type= 85 xkbEvent= 1 calling x11MappingNotify() KGlobalAccelImpl::x11MappingNotify Got XMappingNotify event KGlobalAccelInterface::ungrabKeys KGlobalAccelInterface::grabKeys KGlobalAccelImpl::nativeEventFilter event->response_type= 85 xkbEvent= 1 calling x11MappingNotify() KGlobalAccelImpl::x11MappingNotify Got XMappingNotify event KGlobalAccelInterface::ungrabKeys KGlobalAccelInterface::grabKeys and so on, and so on... The reason why x11MappingNotify() does ungrabKeys+grabKeys is apparently "Maybe the X modifier map has been changed." ... which is not the case at all... What's an XCB_XKB_MAP_NOTIFY anyway? http://manpages.ubuntu.com/manpages/xenial/en/man3/xcb_xkb_map_notify_event_t.3.html is very much incomplete... Is it event really such an event that we're getting? The code says } else if (m_xkb_first_event && responseType == m_xkb_first_event) { const uint8_t xkbEvent = event->pad0; switch (xkbEvent) { case XCB_XKB_MAP_NOTIFY: qDebug() << "event->response_type=" << event->response_type << "xkbEvent=" << xkbEvent << "calling x11MappingNotify()"; x11MappingNotify(); break; What sense does it make that this code is checking pad0, which looks like some padding member? To avoid a downcast to a more specific event type maybe? I'm not sure: * if we're really getting a stream of XCB_XKB_MAP_NOTIFY events or if this code misunderstands that * if so, why is X11 sending such a high number of those * why the code reacts the same to XCB_XKB_MAP_NOTIFY and to XCB_MAPPING_NOTIFY, isn't one enough? Without outside help I guess I would just compress those events using a timer, but that would be a "fix without really understanding the code", never good. I just noticed https://phabricator.kde.org/D16434 so CC'ing Fabian :) -- David Faure, fa...@kde.org, http://www.davidfaure.fr Working on KDE Frameworks 5
