Hi,
I do not experience the lyx-sluggish problem myself so it's difficult test any
proposed solutions.
Tried to push claude to investigate from many angles, but never got something
which would exactly
fit the reports.
I have candidate for a leak when I relax the demand it's 2.5.x only. So it's
present in 2.4 as well,
but perhaps the windows Qt6 transition made it more pronounced?
I am looking for someone who 1) experiences the leak itself and 2) can compile
lyx and test proposed fix(es).
Anyone around?
The patch to test is attached.
Pavel
PS: for @devs this is Claude's theory:
-----------------------
GuiToolbar::update() runs on every keypress and emits updated(), which is
connected to DynamicMenuButton::updateTriggered(). For the "textstyle-apply"
and "paste" buttons, that slot rebuilds the whole dropdown menu each time:
m->clear();
...
Action * act = new Action(func, QIcon(), toqstr(lb), toqstr(s), this);
m->addAction(act);
The actions are parented to this (the button), not to the menu.
QMenu::clear() only deletes actions the menu owns, so these are merely detached
and stay alive as children of the button - for the lifetime of the window.
Every keystroke therefore allocates several new QActions (plus their QStrings)
that are never freed.
Measured on master (Qt5, Linux) with heaptrack, typing into a math-free
document, memory still held at exit:
- 100 chars: +0.41 MB, 400 chars: +1.66 MB, 800 chars: +3.32 MB
- i.e. ~4.15 kB per keystroke, perfectly linear and unbounded
Deleting the stale actions before rebuilding drops this from 4.14 to 0.99 kB
per keystroke (~76%).
------
diff --git a/src/frontends/qt/GuiToolbar.cpp b/src/frontends/qt/GuiToolbar.cpp
index 2e0a6d5819..ddb957273a 100644
--- a/src/frontends/qt/GuiToolbar.cpp
+++ b/src/frontends/qt/GuiToolbar.cpp
@@ -423,6 +423,11 @@ void DynamicMenuButton::updateTriggered()
&& !d->func_requests_.empty()
&& lyx::getStatus(d->func_requests_.front()).enabled());
} else if (menutype == "textstyle-apply") {
+ // LEAK-TEST: QMenu::clear() does NOT delete these actions, because
+ // they are parented to this button, not to the menu. Without this
+ // they accumulate on every toolbar update (i.e. every keystroke).
+ for (QAction * a : m->actions())
+ delete a;
m->clear();
setPopupMode(QToolButton::MenuButtonPopup);
if (!bv) {
@@ -463,6 +468,11 @@ void DynamicMenuButton::updateTriggered()
setEnabled(lyx::getStatus(FuncRequest(LFUN_TEXTSTYLE_APPLY)).enabled()
|| lyx::getStatus(FuncRequest(LFUN_FONT_DEFAULT)).enabled());
} else if (menutype == "paste") {
+ // LEAK-TEST: QMenu::clear() does NOT delete these actions, because
+ // they are parented to this button, not to the menu. Without this
+ // they accumulate on every toolbar update (i.e. every keystroke).
+ for (QAction * a : m->actions())
+ delete a;
m->clear();
setPopupMode(QToolButton::MenuButtonPopup);
Action * default_action = new Action(FuncRequest(LFUN_PASTE),
@@ -496,6 +506,11 @@ void DynamicMenuButton::updateTriggered()
void DynamicMenuButton::loadFlexInsets()
{
QMenu * m = menu();
+ // LEAK-TEST: QMenu::clear() does NOT delete these actions, because
+ // they are parented to this button, not to the menu. Without this
+ // they accumulate on every toolbar update (i.e. every keystroke).
+ for (QAction * a : m->actions())
+ delete a;
m->clear();
d->func_requests_.clear();
string const & menutype = tbitem_.name;
--
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