Bug 464033

> My test file is 100 GB.
OMG

I think what's going on is that the file is being opened or at least stat'ed to check its MIME type to see if it's droppable, and this is non-ideal for huge files.

I can reproduce it with a 5GB file:
1 In dolphin select file
2 start dragging
3 hold ctrl
4 release on desktop

System (plasmashell) hangs for a few seconds, before displaying the drop menu.
This seems not to be be as slow once this is done twice in a row, hinting at a disk cache.


I got this stack trace during the hang :

Thread 1 "plasmashell" received signal SIGINT, Interrupt.
__futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x55a8518e05f0) at ./nptl/futex-internal.c:57
57      ./nptl/futex-internal.c: Aucun fichier ou dossier de ce type.
(gdb) bt
#0  __futex_abstimed_wait_common64
    (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x55a8518e05f0)
    at ./nptl/futex-internal.c:57
#1  __futex_abstimed_wait_common
    (cancel=true, private=0, abstime=0x0, clockid=0, expected=0, futex_word=0x55a8518e05f0)
    at ./nptl/futex-internal.c:87
#2  __GI___futex_abstimed_wait_cancelable64
    (futex_word=futex_word@entry=0x55a8518e05f0, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139
#3  0x00007f290108f338 in __pthread_cond_wait_common
    (abstime=0x0, clockid=0, mutex=0x55a8518e05a0, cond=0x55a8518e05c8) at ./nptl/pthread_cond_wait.c:503
#4  ___pthread_cond_wait (cond=0x55a8518e05c8, mutex=0x55a8518e05a0) at ./nptl/pthread_cond_wait.c:627
#5  0x00007f29018d2b1b in QWaitConditionPrivate::wait(QDeadlineTimer) (deadline=..., this=0x55a8518e05a0)
    at thread/qwaitcondition_unix.cpp:146
#6  QWaitCondition::wait(QMutex*, QDeadlineTimer)
    (this=this@entry=0x55a84ec16828, mutex=mutex@entry=0x55a84ec16808, deadline=...)
    at thread/qwaitcondition_unix.cpp:225
#7  0x00007f29018cc919 in QThread::wait(QDeadlineTimer) (this=<optimized out>, deadline=...)
    at ../../include/QtCore/../../src/corelib/thread/qmutex.h:270
#8  0x00007f28ffc7b98c in  () at /lib/x86_64-linux-gnu/libKF5KIOCore.so.5
#9  0x00007f28ffc7b9ed in  () at /lib/x86_64-linux-gnu/libKF5KIOCore.so.5
#10 0x00007f2901ae55fe in QObjectPrivate::deleteChildren() (this=this@entry=0x55a84fd9a580)
    at kernel/qobject.cpp:2137
#11 0x00007f2901af1744 in QObject::~QObject() (this=<optimized out>, __in_chrg=<optimized out>)
    at kernel/qobject.cpp:1115
--Type <RET> for more, q to quit, c to continue without paging--
#12 0x00007f28ffbfed2c in KIO::Slave::deref() () at /lib/x86_64-linux-gnu/libKF5KIOCore.so.5
#13 0x00007f2901af36ff in QtPrivate::QSlotObjectBase::call(QObject*, void**) (a=0x7ffec45b7e20, r=0x55a84cd1b1f0, this=0x55a8518cfd20)
    at ../../include/QtCore/../../src/corelib/kernel/qobjectdefs_impl.h:398
#14 doActivate<false>(QObject*, int, void**) (sender=0x55a850f32930, signal_index=3, argv=0x7ffec45b7e20) at kernel/qobject.cpp:3919
#15 0x00007f2901ae7b30 in QObject::event(QEvent*) (this=0x55a850f32930, e=0x55a84fda7810) at kernel/qobject.cpp:1347
#16 0x00007f290276bf32 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /lib/x86_64-linux-gnu/libQt5Widgets.so.5
#17 0x00007f2901abae38 in QCoreApplication::notifyInternal2(QObject*, QEvent*) (receiver=0x55a850f32930, event=0x55a84fda7810)
    at kernel/qcoreapplication.cpp:1064
#18 0x00007f2901abdeb1 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) (receiver=0x0, event_type=0, data=0x55a84b507ec0)
    at kernel/qcoreapplication.cpp:1821
#19 0x00007f2901b15427 in postEventSourceDispatch(GSource*, GSourceFunc, gpointer) (s=0x55a84b54c640) at kernel/qeventdispatcher_glib.cpp:277
#20 0x00007f28ffe734f9 in g_main_context_dispatch () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#21 0x00007f28ffec8228 in  () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#22 0x00007f28ffe70cb0 in g_main_context_iteration () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#23 0x00007f2901b14aea in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x55a84b5510d0, flags=...)
    at kernel/qeventdispatcher_glib.cpp:423
#24 0x00007f2901ab97cb in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=this@entry=0x7ffec45b8210, flags=..., flags@entry=...)
    at ../../include/QtCore/../../src/corelib/global/qflags.h:69
#25 0x00007f2901ac1c2a in QCoreApplication::exec() () at ../../include/QtCore/../../src/corelib/global/qflags.h:121
#26 0x000055a84ad6a567 in  ()
#27 0x00007f2901023510 in __libc_start_call_main (main=main@entry=0x55a84ad696b0, argc=argc@entry=1, argv=argv@entry=0x7ffec45b84d8)
    at ../sysdeps/nptl/libc_start_call_main.h:58
#28 0x00007f29010235c9 in __libc_start_main_impl
     (main=0x55a84ad696b0, argc=1, argv=0x7ffec45b84d8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffec45b84c8)
    at ../csu/libc-start.c:381
#29 0x000055a84ad6a685 in  ()

It seems to suggest a sort of memory leak causing Qt not to free memory.
Or maybe that's called in a loop. 

The event in #15 in the stacktrace is :
(gdb) p *e
$3 = {_vptr.QEvent = 0x7f2901d59e98 <vtable for QMetaCallEvent+16>, static staticMetaObject = {d = {
      superdata = {direct = 0x0}, stringdata = 0x7f2901c86100 <qt_meta_stringdata_QEvent>, 
      data = 0x7f2901c85b40 <qt_meta_data_QEvent>, static_metacall = 0x0, relatedMetaObjects = 0x0, 
      extradata = 0x0}}, d = 0x0, t = 43, posted = 0, spont = 0, m_accept = 1, reserved = 0}

With t (43) == QEvent::MetaCall

I don't reproduce it in Plasma 6.1.4.
I would welcome a second confirmation.

How about you, kroot001@gmail.com? Are you still able to reproduce it with Plasma 6.1.4 or later? Thanks for checking!

(In reply to Nate Graham from comment #4)
> How about you, kroot001@gmail.com? Are you still able to reproduce it with
> Plasma 6.1.4 or later? Thanks for checking!

Just tested this on Plasma 6.1.5 and can no longer reproduce the issue. Looks like this can be closed!

Wonderful!