Created attachment 121324 [details] Screen recording of the issue SUMMARY Attempting to Alt + Tab between windows results in a delay of multiple seconds until the window changes. During this "delay" it is not possible to select any other applications from the task bar. It seems as though the system is frozen (accept for mouse movement) until it catches up. This issue just started happening in the past week after upgrading to kwin 5.15.5-2 from 5.15.5-1 STEPS TO REPRODUCE 1. Open GoLand, Google Chrome, and About System 2. Confirm window switching by clicking task bar 3. Press Alt + Tab 4. Wait, wiggle mouse, pass time OBSERVED RESULT System appears to freeze except mouse still functions EXPECTED RESULT Windows change SOFTWARE/OS VERSIONS Linux/KDE Plasma: Fedora 30 KDE Spin (available in About System) KDE Plasma Version: 5.15.5 KDE Frameworks Version: 5.59.0 Qt Version: 5.12.4 ADDITIONAL INFORMATION This may be related to https://bugs.kde.org/show_bug.cgi?id=405103 from my searching, but I don't know enough to be certain. This bug appears to trigger on all windows not just the Goland editor. I've attached a screen recording of the issue. Alt + Tab is pressed at the 9 second mark and the window switching completes at 29 seconds.
Please post output of qdbus org.kde.KWin /KWin supportInformation
KWin Support Information: The following information should be used when requesting support on e.g. https://forum.kde.org. It provides information about the currently running instance, which options are used, what OpenGL driver and which effects are running. Please post the information provided underneath this introductory text to a paste bin service like http://paste.kde.org instead of pasting into support threads. ========================== Version ======= KWin version: 5.15.5 Qt Version: 5.12.4 Qt compile version: 5.12.4 XCB compile version: 1.13.1 Operation Mode: X11 only Build Options ============= KWIN_BUILD_DECORATIONS: yes KWIN_BUILD_TABBOX: yes KWIN_BUILD_ACTIVITIES: yes HAVE_DRM: yes HAVE_GBM: yes HAVE_X11_XCB: yes HAVE_EPOXY_GLX: yes HAVE_WAYLAND_EGL: yes X11 === Vendor: Fedora Project Vendor Release: 12005000 Protocol Version/Revision: 11/0 SHAPE: yes; Version: 0x11 RANDR: yes; Version: 0x14 qdbus org.kde.KWin /KWin supportInformation DAMAGE: yes; Version: 0x11 Composite: yes; Version: 0x4 RENDER: yes; Version: 0xb XFIXES: yes; Version: 0x50 SYNC: yes; Version: 0x31 GLX: yes; Version: 0x0 Decoration ========== Plugin: org.kde.breeze Theme: Blur: 0 onAllDesktopsAvailable: false alphaChannelSupported: true closeOnDoubleClickOnMenu: false decorationButtonsLeft: 0, 2 decorationButtonsRight: 6, 3, 4, 5 borderSize: 3 gridUnit: 26 font: Noto Sans,10,-1,0,50,0,0,0,0,0,Regular smallSpacing: 6 largeSpacing: 26 Platform ========== Name: KWin::X11StandalonePlatform Options ======= focusPolicy: 0 nextFocusPrefersMouse: false clickRaise: true autoRaise: false autoRaiseInterval: 0 delayFocusInterval: 0 shadeHover: false shadeHoverInterval: 250 separateScreenFocus: false placement: 4 focusPolicyIsReasonable: true borderSnapZone: 10 windowSnapZone: 10 centerSnapZone: 0 snapOnlyWhenOverlapping: false rollOverDesktops: true focusStealingPreventionLevel: 1 legacyFullscreenSupport: false operationTitlebarDblClick: 5000 operationMaxButtonLeftClick: 5000 operationMaxButtonMiddleClick: 5015 operationMaxButtonRightClick: 5014 commandActiveTitlebar1: 0 commandActiveTitlebar2: 30 commandActiveTitlebar3: 2 commandInactiveTitlebar1: 4 commandInactiveTitlebar2: 30 commandInactiveTitlebar3: 2 commandWindow1: 7 commandWindow2: 8 commandWindow3: 8 commandWindowWheel: 31 commandAll1: 10 commandAll2: 3 commandAll3: 14 keyCmdAllModKey: 16777251 showGeometryTip: false condensedTitle: false electricBorderMaximize: true electricBorderTiling: true electricBorderCornerRatio: 0.25 borderlessMaximizedWindows: false killPingTimeout: 5000 hideUtilityWindowsForInactive: true inactiveTabsSkipTaskbar: false autogroupSimilarWindows: false autogroupInForeground: true compositingMode: 1 useCompositing: true compositingInitialized: true hiddenPreviews: 1 glSmoothScale: 2 xrenderSmoothScale: false maxFpsInterval: 16666666 refreshRate: 0 vBlankTime: 6000000 glStrictBinding: false glStrictBindingFollowsDriver: true glCoreProfile: false glPreferBufferSwap: 99 glPlatformInterface: 1 windowsBlockCompositing: true Screen Edges ============ desktopSwitching: false desktopSwitchingMovingClients: false cursorPushBackDistance: 1x1 timeThreshold: 150 reActivateThreshold: 350 actionTopLeft: 0 actionTop: 0 actionTopRight: 0 actionRight: 0 actionBottomRight: 0 actionBottom: 0 actionBottomLeft: 0 actionLeft: 0 Screens ======= Multi-Head: no Active screen follows mouse: no Number of Screens: 1 Screen 0: --------- Name: eDP-1-1 Geometry: 0,0,3840x2160 Scale: 1 Refresh Rate: 59.9966 Compositing =========== Compositing is active Compositing Type: OpenGL OpenGL vendor string: NVIDIA Corporation OpenGL renderer string: GeForce GTX 1050 Ti with Max-Q Design/PCIe/SSE2 OpenGL version string: 4.6.0 NVIDIA 430.26 OpenGL platform interface: GLX OpenGL shading language version string: 4.60 NVIDIA Driver: NVIDIA Driver version: 430.26 GPU class: Unknown OpenGL version: 4.6 GLSL version: 4.60 Linux kernel version: 5.1.15 Direct rendering: Requires strict binding: no GLSL shaders: yes Texture NPOT support: yes Virtual Machine: no OpenGL 2 Shaders are used Painting blocks for vertical retrace: yes Loaded Effects: --------------- kwin4_effect_squash zoom kwin4_effect_fadingpopups kwin4_effect_windowaperture kwin4_effect_translucency kwin4_effect_morphingpopups kwin4_effect_maximize kwin4_effect_logout kwin4_effect_login kwin4_effect_frozenapp kwin4_effect_fade kwin4_effect_dialogparent slidingpopups slide screenshot desktopgrid colorpicker presentwindows highlightwindow blur contrast startupfeedback screenedge kscreen Currently Active Effects: ------------------------- blur contrast Effect Settings: ---------------- kwin4_effect_squash: isActiveFullScreenEffect: false zoom: zoomFactor: 1.2 mousePointer: 0 mouseTracking: 0 enableFocusTracking: false followFocus: true focusDelay: 350 moveFactor: 20 targetZoom: 1 kwin4_effect_fadingpopups: isActiveFullScreenEffect: false kwin4_effect_windowaperture: isActiveFullScreenEffect: false kwin4_effect_translucency: isActiveFullScreenEffect: false kwin4_effect_morphingpopups: isActiveFullScreenEffect: false kwin4_effect_maximize: isActiveFullScreenEffect: false kwin4_effect_logout: isActiveFullScreenEffect: false kwin4_effect_login: isActiveFullScreenEffect: false kwin4_effect_frozenapp: isActiveFullScreenEffect: false kwin4_effect_fade: isActiveFullScreenEffect: false kwin4_effect_dialogparent: isActiveFullScreenEffect: false slidingpopups: slideInDuration: 150 slideOutDuration: 250 slide: duration: 500 horizontalGap: 45 verticalGap: 20 slideDocks: false slideBackground: true screenshot: desktopgrid: zoomDuration: 300 border: 10 desktopNameAlignment: 0 layoutMode: 0 customLayoutRows: 2 usePresentWindows: true colorpicker: presentwindows: layoutMode: 0 showCaptions: true showIcons: true doNotCloseWindows: false ignoreMinimized: false accuracy: 20 fillGaps: true fadeDuration: 150 showPanel: false leftButtonWindow: 1 rightButtonWindow: 2 middleButtonWindow: 0 leftButtonDesktop: 2 middleButtonDesktop: 0 rightButtonDesktop: 0 highlightwindow: blur: contrast: startupfeedback: type: 1 screenedge: kscreen:
Jan, you need to backport 56cd5f5557fbec291a9d44f6f26fb76b5c34adae in Fedora.
FWIW this issue was added to reported to Red Hat's bugzilla as well https://bugzilla.redhat.com/show_bug.cgi?id=1727169
Same problem reported against Arch Linux - bug 409766
*** Bug 409766 has been marked as a duplicate of this bug. ***
FWIW, works for me on Manjaro with Plasma 5.16.2 or with everything built from git master.
As posted in the duplicate bug, the same version is having issues in Arch linux. So, I think this is a bug that is a little difficult to reproduce. However, I would recommend that if the issue does not pop up immediately, use the system a bit longer and load the system a bit more. The issue will eventually pop up.
Fedora developers need to backport 56cd5f5557fbec291a9d44f6f26fb76b5c34adae. *** This bug has been marked as a duplicate of bug 406180 ***