Add qt.workarounds.remove_service_workers setting

See #5656, #5634

2 files changed, 22 insertions, 8 deletions

diff --git a/qutebrowser/config/configdata.yml b/qutebrowser/config/configdata.yml
index 69786f2b3..cee077c14 100644
--- a/qutebrowser/config/configdata.yml
+++ b/qutebrowser/config/configdata.yml
@@ -286,6 +286,19 @@ qt.highdpi:
     As an alternative to this, it's possible to set font sizes and the
     `zoom.default` setting.
 
+qt.workarounds.remove_service_workers:
+  type: Bool
+  default: false
+  desc: >-
+    Delete the QtWebEngine Service Worker directory on every start.
+
+    This workaround can help with certain crashes caused by an unknown QtWebEngine bug
+    related to Service Workers. Those crashes happen seemingly immediately on Windows;
+    after one hour of operation on other systems.
+
+    Note however that enabling this option *can lead to data loss* on some pages (as
+    Service Worker data isn't persisted) and will negatively impact start-up time.
+
 ## auto_save
 
 auto_save.interval:
diff --git a/qutebrowser/misc/backendproblem.py b/qutebrowser/misc/backendproblem.py
index 1011e539d..b5f72b521 100644
--- a/qutebrowser/misc/backendproblem.py
+++ b/qutebrowser/misc/backendproblem.py
@@ -403,21 +403,22 @@ class _BackendProblemChecker:
             # Nuke the service worker directory once for every install with Qt
             # 5.14, given that it seems to cause a variety of segfaults.
             configfiles.state['general']['serviceworker_workaround'] = '514'
-            affected = True
+            reason = 'Qt 5.14'
+        elif configfiles.state.qt_version_changed:
+            reason = 'Qt version changed'
+        elif config.val.qt.workarounds.remove_service_workers:
+            reason = 'Explicitly enabled'
         else:
-            # Otherwise, just nuke it when the Qt version changed.
-            affected = configfiles.state.qt_version_changed
-
-        if not affected:
             return
 
-        service_worker_dir = os.path.join(standarddir.data(), 'webengine',
-                                          'Service Worker')
+        service_worker_dir = os.path.join(
+            standarddir.data(), 'webengine', 'Service Worker')
         bak_dir = service_worker_dir + '-bak'
         if not os.path.exists(service_worker_dir):
             return
 
-        log.init.info("Qt version changed, removing service workers")
+        log.init.info(
+            f"Removing service workers at {service_worker_dir} (reason: {reason})")
 
         # Keep one backup around - we're not 100% sure what persistent data
         # could be in there, but this folder can grow to ~300 MB.