Copying output from console causes large mem usage/OOM

[fanquake]

Moved from bitcoin/bitcoin#33285.

Is there an existing issue for this?

• I have searched the existing issues

Current behaviour

Running the GUI on mainnet, I open the console, run:

getblocktemplate '{"rules": ["segwit"]}'

everything acts normally until then. If I then try to copy the test, memory usage blows out:

on release build, jumps from <2GB to >7GB memory

on debug build, it jumps to dozens of GB, often causing OOM and kills the process.

Expected behaviour

I expect the memory usage to not blow up on basic operations.

Steps to reproduce

Already detailed.

Relevant log output

No logs after the block generated is tested for validity.

How did you obtain Bitcoin Core

Compiled from source

What version of Bitcoin Core are you using?

master@7e58c94112d0

Operating system and version

Ubuntu 24.04.2 LTS

Machine specifications

64GB of memory

[hebasto]

I can confirm this issue on Ubuntu 24.04 with the system's Qt 6.4.2.

However, a static build using Qt 6.7.3 from depends works perfectly. Perhaps this Qt issue was resolved upstream at some point?

[davidgumberg]

However, a static build using Qt 6.7.3 from depends works perfectly. Perhaps this Qt issue was resolved upstream at some point?

I experience this issue linking against system Qt 6.9.1, so I do not think this has been fixed upstream.

But in our depends build we set -no-feature-textmarkdownwriter:

gui/depends/packages/qt.mk

Line 103 in 689a321

$(package)_config_opts += -no-feature-textmarkdownwriter

and when that feature is disabled, QTextEditMimeData won't try to convert the selection to markdown, avoiding the problematic function:

void QTextEditMimeData::setup() const
{
    // [ Populate other mime data formats... ]
#if QT_CONFIG(textmarkdownwriter)
    that->setData("text/markdown"_L1, fragment.toMarkdown().toUtf8());
#endif
    that->setText(fragment.toPlainText());
}

https://github.com/qt/qtbase/blob/b617d1176593963a2a9ed21dd5d9a63e84a09400/src/widgets/widgets/qwidgettextcontrol.cpp#L3538-L3540