rutsky/MaterialTest.qml

## material_test.py
# PyQt 5.4.2 bug example: QSGMaterial::createShader() result object is destroyed
# before use + application hangs at exit

import textwrap
import sys

from PyQt5.QtQuick import (
    QQuickItem, QSGMaterial,
    QSGMaterialShader, QSGMaterialType,
    QSGGeometry, QSGGeometryNode, QSGNode, QQuickView
    )
from PyQt5.QtQml import (
    qmlRegisterType, QQmlEngine, QQmlComponent, QQmlImageProviderBase,
    QQmlProperty)
from PyQt5.QtCore import pyqtProperty, pyqtSignal, QUrl, QTimer
from PyQt5.QtWidgets import QApplication


class MyMaterialShader(QSGMaterialShader):
    def __init__(self):
        super().__init__()

        self._matrix_uniform_id = None

        print("MyMaterialShader() created")

    def updateState(self, state, material, old_material):
        if state.isMatrixDirty():
            self.program().setUniformValue(
                self._matrix_uniform_id, state.combinedMatrix())

        if not isinstance(material, MyMaterial):
            return

    def attributeNames(self):
        return ["qt_VertexPosition", "qt_VertexTexCoord"]

    def initialize(self):
        self._matrix_uniform_id = self.program().uniformLocation("qt_Matrix")

    def vertexShader(self):
        return textwrap.dedent("""\
            uniform highp mat4 qt_Matrix;

            attribute highp vec4 qt_VertexPosition;
            attribute highp vec2 qt_VertexTexCoord;

            varying highp vec2 qt_TexCoord;

            void main()
            {
                qt_TexCoord = qt_VertexTexCoord;
                gl_Position = qt_Matrix * qt_VertexPosition;
            }
            """)

    def fragmentShader(self):
        return textwrap.dedent("""\
            varying highp vec2 qt_TexCoord;

            void main()
            {
                gl_FragColor = vec4(qt_TexCoord.x, qt_TexCoord.y, 1, 1);
            }
            """)

    def __del__(self):
        print("MyMaterialShader() destroyed")


class MyMaterial(QSGMaterial):
    _type = QSGMaterialType()

    def __init__(self):
        super().__init__()

    def compare(self, other_material):
        if self is other_material:
            return 0
        else:
            return -1 if id(self) < id(other_material) else 1

    def createShader(self):
        shader = MyMaterialShader()

        # Problem #1: created in Python QSGMaterialShader object is being
        # destroyed when not referenced by Python.
        # QSGMaterialShader's are cached inside Qt and rarely destroyed,
        # so Qt fails with segfault when tries to use destroyed object.

        # Workaround: store Python QSGMaterialShader objects indefinitely.
        self._shader = shader  # uncomment this for workaround

        return shader

    def type(self):
        return self._type


class CustomShaderItem(QQuickItem):
    def __init__(self):
        super().__init__()

        self.setFlag(QQuickItem.ItemHasContents, True)

    def updatePaintNode(self, root_node, node_data):
        print("Root node:", root_node)
        if root_node is None:
            root_node = QSGGeometryNode()

            material = MyMaterial()
            root_node.setMaterial(material)
            root_node.setFlag(QSGNode.OwnsMaterial)

            x = 0
            y = 0
            width = 100
            height = 100

            geometry = QSGGeometry(
                QSGGeometry.defaultAttributes_TexturedPoint2D(),
                5)
            geometry.setDrawingMode(QSGGeometry.GL_TRIANGLE_STRIP)
            root_node.setGeometry(geometry)
            root_node.setFlag(QSGNode.OwnsGeometry)

            vertices = geometry.vertexDataAsTexturedPoint2D()
            vertices[0].set(x, y, 0, 0)
            vertices[1].set(x + width, y, 1, 0)
            vertices[2].set(x + width, y + height, 1, 1)
            vertices[3].set(x, y + height, 0, 1)
            vertices[4].set(x, y, 0, 0)

            root_node.markDirty(QSGNode.DirtyGeometry)
            root_node.markDirty(QSGNode.DirtyMaterial)

            # According to documentation, lifetime of QSGNode is managed by Qt,
            # so we cannot safely store it in Python.
            # Transfer ownership to C++ to workaround this issue.
            import sip
            sip.transferto(root_node, root_node)

        return root_node


def main():
    app = QApplication(sys.argv)

    qml_engine = QQmlEngine()

    view = QQuickView(qml_engine, None)

    scene_uri = QUrl.fromLocalFile("MaterialTest.qml")
    view.setSource(scene_uri)
    assert not view.errors()

    shader_item = CustomShaderItem()
    shader_item.setProperty("parent", view.rootObject())

    view.show()

    exit_code = app.exec_()

    #print("Destroying QQuickView")
    #del view
    #print("QQuickView destroyed")
    # Problem #2: destroying QQuickView that used Python-created QSGGeometryNode
    # leads to deadlock.
    #
    # As I see, when QQuickView is being destroyed it waits until render thread
    # clean ups all resources, which causes QSGGeometryNode to be destroyed,
    # which asks to lock GIL, which is still locked by main thread.
    #
    # Here is stack traces at the moment of deadlock:
    #
    #     (gdb) info threads
    #       Id   Target Id         Frame
    #       4    Thread 0x7f705ca83700 (LWP 23802) "QXcbEventReader" 0x00007f706b51c12d in poll () at ../sysdeps/unix/syscall-template.S:81
    #       3    Thread 0x7f7057df9700 (LWP 23803) "QQmlThread" 0x00007f706b51c12d in poll () at ../sysdeps/unix/syscall-template.S:81
    #       2    Thread 0x7f7055aa7700 (LWP 23804) "QSGRenderThread" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
    #     * 1    Thread 0x7f706bf21780 (LWP 23801) "python" pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
    #     (gdb) bt
    #     #0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
    #     #1  0x00007f706505e482 in QWaitConditionPrivate::wait (this=0x2cffb00, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:136
    #     #2  0x00007f706505e255 in QWaitCondition::wait (this=0x2cff538, mutex=0x2cff530, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:208
    #     #3  0x00007f70664b4527 in QSGThreadedRenderLoop::releaseResources (this=0x2a09600, w=0x27dcb80, inDestructor=true) at scenegraph/qsgthreadedrenderloop.cpp:1059
    #     #4  0x00007f70664b2ed8 in QSGThreadedRenderLoop::windowDestroyed (this=0x2a09600, window=0x2768670) at scenegraph/qsgthreadedrenderloop.cpp:825
    #     #5  0x00007f70664ad512 in QSGRenderLoop::cleanup () at scenegraph/qsgrenderloop.cpp:94
    #     #6  0x00007f70652d2c9e in qt_call_post_routines () at kernel/qcoreapplication.cpp:294
    #     #7  0x00007f705fdc6734 in QApplication::~QApplication (this=0x26c6ed0, __in_chrg=<optimized out>) at kernel/qapplication.cpp:808
    #     #8  0x00007f70607e5758 in sipQApplication::~sipQApplication (this=0x26c6ed0, __in_chrg=<optimized out>) at sipQtWidgetspart0.cpp:301912
    #     #9  0x00007f70607e5788 in sipQApplication::~sipQApplication (this=0x26c6ed0, __in_chrg=<optimized out>) at sipQtWidgetspart0.cpp:301915
    #     #10 0x00007f70607e8f21 in release_QApplication (sipCppV=0x26c6ed0) at sipQtWidgetspart0.cpp:303524
    #     #11 0x00007f70607e8fba in dealloc_QApplication (sipSelf=0x7f705fc42168) at sipQtWidgetspart0.cpp:303538
    #     #12 0x00007f7061cae346 in ?? () from /home/bob/work/proplan/env/lib/python3.4/site-packages/sip.so
    #     #13 0x00007f7061caf5e9 in ?? () from /home/bob/work/proplan/env/lib/python3.4/site-packages/sip.so
    #     #14 0x0000000000598732 in subtype_dealloc.lto_priv () at ../Objects/typeobject.c:1201
    #     #15 0x00000000004c88c7 in frame_dealloc.lto_priv () at ../Objects/frameobject.c:429
    #     #16 0x0000000000503dfb in fast_function (nk=<optimized out>, na=<optimized out>, n=0, pp_stack=0x7ffd401cf350, func=<optimized out>) at ../Python/ceval.c:4336
    #     #17 call_function (oparg=<optimized out>, pp_stack=0x7ffd401cf350) at ../Python/ceval.c:4262
    #     #18 PyEval_EvalFrameEx () at ../Python/ceval.c:2838
    #     #19 0x00000000005a9cb5 in PyEval_EvalCodeEx () at ../Python/ceval.c:3588
    #     Python Exception <class 'RuntimeError'> Type does not have a target.:
    #     Python Exception <class 'RuntimeError'> Type does not have a target.:
    #     #20 0x00000000005e7105 in PyEval_EvalCode (locals=, globals=, co=<code at remote 0x7f706bdf5420>) at ../Python/ceval.c:775
    #     #21 run_mod () at ../Python/pythonrun.c:2180
    #     #22 0x00000000005e71c9 in PyRun_FileExFlags () at ../Python/pythonrun.c:2133
    #     #23 0x00000000005e79aa in PyRun_SimpleFileExFlags () at ../Python/pythonrun.c:1606
    #     #24 0x00000000005fb69d in run_file (p_cf=<optimized out>, filename=<optimized out>, fp=<optimized out>) at ../Modules/main.c:319
    #     #25 Py_Main () at ../Modules/main.c:751
    #     #26 0x00000000004c2e7f in main () at ../Modules/python.c:69
    #     #27 0x00007f706b450ec5 in __libc_start_main (main=0x4c2da0 <main>, argc=2, argv=0x7ffd401cf7c8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffd401cf7b8)
    #         at libc-start.c:287
    #     #28 0x00000000005b8db9 in _start ()
    #     (gdb) thread 2
    #     [Switching to thread 2 (Thread 0x7f7055aa7700 (LWP 23804))]
    #     #0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
    #     238     ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S: No such file or directory.
    #     (gdb) bt
    #     #0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
    #     #1  0x00000000004ff96c in PyCOND_TIMEDWAIT (cond=<optimized out>, mut=<optimized out>, us=5000) at ../Python/condvar.h:103
    #     #2  take_gil.lto_priv () at ../Python/ceval_gil.h:224
    #     #3  0x00000000004ffb43 in PyEval_RestoreThread () at ../Python/ceval.c:448
    #     #4  0x00000000005e7c67 in PyGILState_Ensure () at ../Python/pystate.c:793
    #     #5  0x00007f7061cb6307 in ?? () from /home/bob/work/proplan/env/lib/python3.4/site-packages/sip.so
    #     #6  0x00007f7066888341 in sipQSGGeometryNode::~sipQSGGeometryNode (this=0x7f70480e6580, __in_chrg=<optimized out>) at sipQtQuickpart0.cpp:7733
    #     #7  0x00007f706688837c in sipQSGGeometryNode::~sipQSGGeometryNode (this=0x7f70480e6580, __in_chrg=<optimized out>) at sipQtQuickpart0.cpp:7734
    #     #8  0x00007f706646a178 in QSGNode::destroy (this=0x7f70480e6210) at scenegraph/coreapi/qsgnode.cpp:389
    #     #9  0x00007f706646a01d in QSGNode::~QSGNode (this=0x7f70480e6210, __in_chrg=<optimized out>) at scenegraph/coreapi/qsgnode.cpp:320
    #     #10 0x00007f706646a05c in QSGNode::~QSGNode (this=0x7f70480e6210, __in_chrg=<optimized out>) at scenegraph/coreapi/qsgnode.cpp:321
    #     #11 0x00007f706646a178 in QSGNode::destroy (this=0x7f70480e6080) at scenegraph/coreapi/qsgnode.cpp:389
    #     #12 0x00007f706646a01d in QSGNode::~QSGNode (this=0x7f70480e6080, __in_chrg=<optimized out>) at scenegraph/coreapi/qsgnode.cpp:320
    #     #13 0x00007f706646b49e in QSGTransformNode::~QSGTransformNode (this=0x7f70480e6080, __in_chrg=<optimized out>) at scenegraph/coreapi/qsgnode.cpp:1156
    #     #14 0x00007f706646b4ce in QSGTransformNode::~QSGTransformNode (this=0x7f70480e6080, __in_chrg=<optimized out>) at scenegraph/coreapi/qsgnode.cpp:1158
    #     #15 0x00007f70664efcb7 in QQuickWindowPrivate::cleanupNodesOnShutdown (item=0x273d390) at items/qquickwindow.cpp:2588
    #     #16 0x00007f70664effc4 in QQuickWindowPrivate::cleanupNodesOnShutdown (item=0x2d31f90) at items/qquickwindow.cpp:2616
    #     #17 0x00007f70664effc4 in QQuickWindowPrivate::cleanupNodesOnShutdown (item=0x2a052d0) at items/qquickwindow.cpp:2616
    #     #18 0x00007f70664f002b in QQuickWindowPrivate::cleanupNodesOnShutdown (this=0x2a057b0) at items/qquickwindow.cpp:2624
    #     #19 0x00007f70664b0df5 in QSGRenderThread::invalidateOpenGL (this=0x2cff4f0, window=0x2768670, inDestructor=true, fallback=0x2cff590) at scenegraph/qsgthreadedrenderloop.cpp:465
    #     #20 0x00007f70664b0520 in QSGRenderThread::event (this=0x2cff4f0, e=0x2cfd3f0) at scenegraph/qsgthreadedrenderloop.cpp:390
    #     #21 0x00007f70664b2078 in QSGRenderThread::processEventsAndWaitForMore (this=0x2cff4f0) at scenegraph/qsgthreadedrenderloop.cpp:644
    #     #22 0x00007f70664b23f3 in QSGRenderThread::run (this=0x2cff4f0) at scenegraph/qsgthreadedrenderloop.cpp:672
    #     #23 0x00007f706505cd9b in QThreadPrivate::start (arg=0x2cff4f0) at thread/qthread_unix.cpp:337
    #     #24 0x00007f706b7fc182 in start_thread (arg=0x7f7055aa7700) at pthread_create.c:312
    #     #25 0x00007f706b52947d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
    #     (gdb) thread 3
    #     [Switching to thread 3 (Thread 0x7f7057df9700 (LWP 23803))]
    #     #0  0x00007f706b51c12d in poll () at ../sysdeps/unix/syscall-template.S:81
    #     81      ../sysdeps/unix/syscall-template.S: No such file or directory.
    #     (gdb) bt
    #     #0  0x00007f706b51c12d in poll () at ../sysdeps/unix/syscall-template.S:81
    #     #1  0x00007f7063bc0fe4 in g_main_context_poll (priority=2147483647, n_fds=1, fds=0x7f70500013e0, timeout=-1, context=0x7f70500009b0) at /build/buildd/glib2.0-2.40.2/./glib/gmain.c:4028
    #     #2  g_main_context_iterate (context=context@entry=0x7f70500009b0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at /build/buildd/glib2.0-2.40.2/./glib/gmain.c:3729
    #     #3  0x00007f7063bc10ec in g_main_context_iteration (context=0x7f70500009b0, may_block=1) at /build/buildd/glib2.0-2.40.2/./glib/gmain.c:3795
    #     #4  0x00007f706534d149 in QEventDispatcherGlib::processEvents (this=0x7f70500008e0, flags=...) at kernel/qeventdispatcher_glib.cpp:418
    #     #5  0x00007f70652d0f1e in QEventLoop::processEvents (this=0x7f7057df8e10, flags=...) at kernel/qeventloop.cpp:128
    #     #6  0x00007f70652d11df in QEventLoop::exec (this=0x7f7057df8e10, flags=...) at kernel/qeventloop.cpp:204
    #     #7  0x00007f70650558e0 in QThread::exec (this=0x2732370) at thread/qthread.cpp:503
    #     #8  0x00007f706598c5c5 in QQmlThreadPrivate::run (this=0x2732370) at qml/ftw/qqmlthread.cpp:141
    #     #9  0x00007f706505cd9b in QThreadPrivate::start (arg=0x2732370) at thread/qthread_unix.cpp:337
    #     #10 0x00007f706b7fc182 in start_thread (arg=0x7f7057df9700) at pthread_create.c:312
    #     #11 0x00007f706b52947d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
    #     (gdb) thread 4
    #     [Switching to thread 4 (Thread 0x7f705ca83700 (LWP 23802))]
    #     #0  0x00007f706b51c12d in poll () at ../sysdeps/unix/syscall-template.S:81
    #     81      in ../sysdeps/unix/syscall-template.S
    #     (gdb) bt
    #     #0  0x00007f706b51c12d in poll () at ../sysdeps/unix/syscall-template.S:81
    #     #1  0x00007f7067770b72 in poll (__timeout=-1, __nfds=1, __fds=0x7f705ca82d00) at /usr/include/x86_64-linux-gnu/bits/poll2.h:46
    #     #2  _xcb_conn_wait (c=c@entry=0x28a2c60, cond=cond@entry=0x28a2ca0, vector=vector@entry=0x0, count=count@entry=0x0) at ../../src/xcb_conn.c:447
    #     #3  0x00007f706777264f in xcb_wait_for_event (c=0x28a2c60) at ../../src/xcb_in.c:622
    #     #4  0x00007f705fb3df81 in QXcbEventReader::run (this=0x28b0b90) at qxcbconnection.cpp:1105
    #     #5  0x00007f706505cd9b in QThreadPrivate::start (arg=0x28b0b90) at thread/qthread_unix.cpp:337
    #     #6  0x00007f706b7fc182 in start_thread (arg=0x7f705ca83700) at pthread_create.c:312
    #     #7  0x00007f706b52947d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
    #
    # (This issue is not reproduces in Windows, since Qt 5.4 still uses single
    # threaded rendering there.)

    return exit_code


if __name__ == "__main__":
    exit_code = main()
    sys.exit(exit_code)

## MaterialTest.qml
import QtQuick 2.0

Item {
}
	# PyQt 5.4.2 bug example: QSGMaterial::createShader() result object is destroyed
	# before use + application hangs at exit

	import textwrap
	import sys

	from PyQt5.QtQuick import (
	QQuickItem, QSGMaterial,
	QSGMaterialShader, QSGMaterialType,
	QSGGeometry, QSGGeometryNode, QSGNode, QQuickView
	)
	from PyQt5.QtQml import (
	qmlRegisterType, QQmlEngine, QQmlComponent, QQmlImageProviderBase,
	QQmlProperty)
	from PyQt5.QtCore import pyqtProperty, pyqtSignal, QUrl, QTimer
	from PyQt5.QtWidgets import QApplication


	class MyMaterialShader(QSGMaterialShader):
	def __init__(self):
	super().__init__()

	self._matrix_uniform_id = None

	print("MyMaterialShader() created")

	def updateState(self, state, material, old_material):
	if state.isMatrixDirty():
	self.program().setUniformValue(
	self._matrix_uniform_id, state.combinedMatrix())

	if not isinstance(material, MyMaterial):
	return

	def attributeNames(self):
	return ["qt_VertexPosition", "qt_VertexTexCoord"]

	def initialize(self):
	self._matrix_uniform_id = self.program().uniformLocation("qt_Matrix")

	def vertexShader(self):
	return textwrap.dedent("""\
	uniform highp mat4 qt_Matrix;

	attribute highp vec4 qt_VertexPosition;
	attribute highp vec2 qt_VertexTexCoord;

	varying highp vec2 qt_TexCoord;

	void main()
	{
	qt_TexCoord = qt_VertexTexCoord;
	gl_Position = qt_Matrix * qt_VertexPosition;
	}
	""")

	def fragmentShader(self):
	return textwrap.dedent("""\
	varying highp vec2 qt_TexCoord;

	void main()
	{
	gl_FragColor = vec4(qt_TexCoord.x, qt_TexCoord.y, 1, 1);
	}
	""")

	def __del__(self):
	print("MyMaterialShader() destroyed")


	class MyMaterial(QSGMaterial):
	_type = QSGMaterialType()

	def __init__(self):
	super().__init__()

	def compare(self, other_material):
	if self is other_material:
	return 0
	else:
	return -1 if id(self) < id(other_material) else 1

	def createShader(self):
	shader = MyMaterialShader()

	# Problem #1: created in Python QSGMaterialShader object is being
	# destroyed when not referenced by Python.
	# QSGMaterialShader's are cached inside Qt and rarely destroyed,
	# so Qt fails with segfault when tries to use destroyed object.

	# Workaround: store Python QSGMaterialShader objects indefinitely.
	self._shader = shader # uncomment this for workaround

	return shader

	def type(self):
	return self._type


	class CustomShaderItem(QQuickItem):
	def __init__(self):
	super().__init__()

	self.setFlag(QQuickItem.ItemHasContents, True)

	def updatePaintNode(self, root_node, node_data):
	print("Root node:", root_node)
	if root_node is None:
	root_node = QSGGeometryNode()

	material = MyMaterial()
	root_node.setMaterial(material)
	root_node.setFlag(QSGNode.OwnsMaterial)

	x = 0
	y = 0
	width = 100
	height = 100

	geometry = QSGGeometry(
	QSGGeometry.defaultAttributes_TexturedPoint2D(),
	5)
	geometry.setDrawingMode(QSGGeometry.GL_TRIANGLE_STRIP)
	root_node.setGeometry(geometry)
	root_node.setFlag(QSGNode.OwnsGeometry)

	vertices = geometry.vertexDataAsTexturedPoint2D()
	vertices[0].set(x, y, 0, 0)
	vertices[1].set(x + width, y, 1, 0)
	vertices[2].set(x + width, y + height, 1, 1)
	vertices[3].set(x, y + height, 0, 1)
	vertices[4].set(x, y, 0, 0)

	root_node.markDirty(QSGNode.DirtyGeometry)
	root_node.markDirty(QSGNode.DirtyMaterial)

	# According to documentation, lifetime of QSGNode is managed by Qt,
	# so we cannot safely store it in Python.
	# Transfer ownership to C++ to workaround this issue.
	import sip
	sip.transferto(root_node, root_node)

	return root_node


	def main():
	app = QApplication(sys.argv)

	qml_engine = QQmlEngine()

	view = QQuickView(qml_engine, None)

	scene_uri = QUrl.fromLocalFile("MaterialTest.qml")
	view.setSource(scene_uri)
	assert not view.errors()

	shader_item = CustomShaderItem()
	shader_item.setProperty("parent", view.rootObject())

	view.show()

	exit_code = app.exec_()

	#print("Destroying QQuickView")
	#del view
	#print("QQuickView destroyed")
	# Problem #2: destroying QQuickView that used Python-created QSGGeometryNode
	# leads to deadlock.
	#
	# As I see, when QQuickView is being destroyed it waits until render thread
	# clean ups all resources, which causes QSGGeometryNode to be destroyed,
	# which asks to lock GIL, which is still locked by main thread.
	#
	# Here is stack traces at the moment of deadlock:
	#
	# (gdb) info threads
	# Id Target Id Frame
	# 4 Thread 0x7f705ca83700 (LWP 23802) "QXcbEventReader" 0x00007f706b51c12d in poll () at ../sysdeps/unix/syscall-template.S:81
	# 3 Thread 0x7f7057df9700 (LWP 23803) "QQmlThread" 0x00007f706b51c12d in poll () at ../sysdeps/unix/syscall-template.S:81
	# 2 Thread 0x7f7055aa7700 (LWP 23804) "QSGRenderThread" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
	# * 1 Thread 0x7f706bf21780 (LWP 23801) "python" pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
	# (gdb) bt
	# #0 pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
	# #1 0x00007f706505e482 in QWaitConditionPrivate::wait (this=0x2cffb00, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:136
	# #2 0x00007f706505e255 in QWaitCondition::wait (this=0x2cff538, mutex=0x2cff530, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:208
	# #3 0x00007f70664b4527 in QSGThreadedRenderLoop::releaseResources (this=0x2a09600, w=0x27dcb80, inDestructor=true) at scenegraph/qsgthreadedrenderloop.cpp:1059
	# #4 0x00007f70664b2ed8 in QSGThreadedRenderLoop::windowDestroyed (this=0x2a09600, window=0x2768670) at scenegraph/qsgthreadedrenderloop.cpp:825
	# #5 0x00007f70664ad512 in QSGRenderLoop::cleanup () at scenegraph/qsgrenderloop.cpp:94
	# #6 0x00007f70652d2c9e in qt_call_post_routines () at kernel/qcoreapplication.cpp:294
	# #7 0x00007f705fdc6734 in QApplication::~QApplication (this=0x26c6ed0, __in_chrg=<optimized out>) at kernel/qapplication.cpp:808
	# #8 0x00007f70607e5758 in sipQApplication::~sipQApplication (this=0x26c6ed0, __in_chrg=<optimized out>) at sipQtWidgetspart0.cpp:301912
	# #9 0x00007f70607e5788 in sipQApplication::~sipQApplication (this=0x26c6ed0, __in_chrg=<optimized out>) at sipQtWidgetspart0.cpp:301915
	# #10 0x00007f70607e8f21 in release_QApplication (sipCppV=0x26c6ed0) at sipQtWidgetspart0.cpp:303524
	# #11 0x00007f70607e8fba in dealloc_QApplication (sipSelf=0x7f705fc42168) at sipQtWidgetspart0.cpp:303538
	# #12 0x00007f7061cae346 in ?? () from /home/bob/work/proplan/env/lib/python3.4/site-packages/sip.so
	# #13 0x00007f7061caf5e9 in ?? () from /home/bob/work/proplan/env/lib/python3.4/site-packages/sip.so
	# #14 0x0000000000598732 in subtype_dealloc.lto_priv () at ../Objects/typeobject.c:1201
	# #15 0x00000000004c88c7 in frame_dealloc.lto_priv () at ../Objects/frameobject.c:429
	# #16 0x0000000000503dfb in fast_function (nk=<optimized out>, na=<optimized out>, n=0, pp_stack=0x7ffd401cf350, func=<optimized out>) at ../Python/ceval.c:4336
	# #17 call_function (oparg=<optimized out>, pp_stack=0x7ffd401cf350) at ../Python/ceval.c:4262
	# #18 PyEval_EvalFrameEx () at ../Python/ceval.c:2838
	# #19 0x00000000005a9cb5 in PyEval_EvalCodeEx () at ../Python/ceval.c:3588
	# Python Exception <class 'RuntimeError'> Type does not have a target.:
	# Python Exception <class 'RuntimeError'> Type does not have a target.:
	# #20 0x00000000005e7105 in PyEval_EvalCode (locals=, globals=, co=<code at remote 0x7f706bdf5420>) at ../Python/ceval.c:775
	# #21 run_mod () at ../Python/pythonrun.c:2180
	# #22 0x00000000005e71c9 in PyRun_FileExFlags () at ../Python/pythonrun.c:2133
	# #23 0x00000000005e79aa in PyRun_SimpleFileExFlags () at ../Python/pythonrun.c:1606
	# #24 0x00000000005fb69d in run_file (p_cf=<optimized out>, filename=<optimized out>, fp=<optimized out>) at ../Modules/main.c:319
	# #25 Py_Main () at ../Modules/main.c:751
	# #26 0x00000000004c2e7f in main () at ../Modules/python.c:69
	# #27 0x00007f706b450ec5 in __libc_start_main (main=0x4c2da0 <main>, argc=2, argv=0x7ffd401cf7c8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffd401cf7b8)
	# at libc-start.c:287
	# #28 0x00000000005b8db9 in _start ()
	# (gdb) thread 2
	# [Switching to thread 2 (Thread 0x7f7055aa7700 (LWP 23804))]
	# #0 pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
	# 238 ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S: No such file or directory.
	# (gdb) bt
	# #0 pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
	# #1 0x00000000004ff96c in PyCOND_TIMEDWAIT (cond=<optimized out>, mut=<optimized out>, us=5000) at ../Python/condvar.h:103
	# #2 take_gil.lto_priv () at ../Python/ceval_gil.h:224
	# #3 0x00000000004ffb43 in PyEval_RestoreThread () at ../Python/ceval.c:448
	# #4 0x00000000005e7c67 in PyGILState_Ensure () at ../Python/pystate.c:793
	# #5 0x00007f7061cb6307 in ?? () from /home/bob/work/proplan/env/lib/python3.4/site-packages/sip.so
	# #6 0x00007f7066888341 in sipQSGGeometryNode::~sipQSGGeometryNode (this=0x7f70480e6580, __in_chrg=<optimized out>) at sipQtQuickpart0.cpp:7733
	# #7 0x00007f706688837c in sipQSGGeometryNode::~sipQSGGeometryNode (this=0x7f70480e6580, __in_chrg=<optimized out>) at sipQtQuickpart0.cpp:7734
	# #8 0x00007f706646a178 in QSGNode::destroy (this=0x7f70480e6210) at scenegraph/coreapi/qsgnode.cpp:389
	# #9 0x00007f706646a01d in QSGNode::~QSGNode (this=0x7f70480e6210, __in_chrg=<optimized out>) at scenegraph/coreapi/qsgnode.cpp:320
	# #10 0x00007f706646a05c in QSGNode::~QSGNode (this=0x7f70480e6210, __in_chrg=<optimized out>) at scenegraph/coreapi/qsgnode.cpp:321
	# #11 0x00007f706646a178 in QSGNode::destroy (this=0x7f70480e6080) at scenegraph/coreapi/qsgnode.cpp:389
	# #12 0x00007f706646a01d in QSGNode::~QSGNode (this=0x7f70480e6080, __in_chrg=<optimized out>) at scenegraph/coreapi/qsgnode.cpp:320
	# #13 0x00007f706646b49e in QSGTransformNode::~QSGTransformNode (this=0x7f70480e6080, __in_chrg=<optimized out>) at scenegraph/coreapi/qsgnode.cpp:1156
	# #14 0x00007f706646b4ce in QSGTransformNode::~QSGTransformNode (this=0x7f70480e6080, __in_chrg=<optimized out>) at scenegraph/coreapi/qsgnode.cpp:1158
	# #15 0x00007f70664efcb7 in QQuickWindowPrivate::cleanupNodesOnShutdown (item=0x273d390) at items/qquickwindow.cpp:2588
	# #16 0x00007f70664effc4 in QQuickWindowPrivate::cleanupNodesOnShutdown (item=0x2d31f90) at items/qquickwindow.cpp:2616
	# #17 0x00007f70664effc4 in QQuickWindowPrivate::cleanupNodesOnShutdown (item=0x2a052d0) at items/qquickwindow.cpp:2616
	# #18 0x00007f70664f002b in QQuickWindowPrivate::cleanupNodesOnShutdown (this=0x2a057b0) at items/qquickwindow.cpp:2624
	# #19 0x00007f70664b0df5 in QSGRenderThread::invalidateOpenGL (this=0x2cff4f0, window=0x2768670, inDestructor=true, fallback=0x2cff590) at scenegraph/qsgthreadedrenderloop.cpp:465
	# #20 0x00007f70664b0520 in QSGRenderThread::event (this=0x2cff4f0, e=0x2cfd3f0) at scenegraph/qsgthreadedrenderloop.cpp:390
	# #21 0x00007f70664b2078 in QSGRenderThread::processEventsAndWaitForMore (this=0x2cff4f0) at scenegraph/qsgthreadedrenderloop.cpp:644
	# #22 0x00007f70664b23f3 in QSGRenderThread::run (this=0x2cff4f0) at scenegraph/qsgthreadedrenderloop.cpp:672
	# #23 0x00007f706505cd9b in QThreadPrivate::start (arg=0x2cff4f0) at thread/qthread_unix.cpp:337
	# #24 0x00007f706b7fc182 in start_thread (arg=0x7f7055aa7700) at pthread_create.c:312
	# #25 0x00007f706b52947d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
	# (gdb) thread 3
	# [Switching to thread 3 (Thread 0x7f7057df9700 (LWP 23803))]
	# #0 0x00007f706b51c12d in poll () at ../sysdeps/unix/syscall-template.S:81
	# 81 ../sysdeps/unix/syscall-template.S: No such file or directory.
	# (gdb) bt
	# #0 0x00007f706b51c12d in poll () at ../sysdeps/unix/syscall-template.S:81
	# #1 0x00007f7063bc0fe4 in g_main_context_poll (priority=2147483647, n_fds=1, fds=0x7f70500013e0, timeout=-1, context=0x7f70500009b0) at /build/buildd/glib2.0-2.40.2/./glib/gmain.c:4028
	# #2 g_main_context_iterate (context=context@entry=0x7f70500009b0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at /build/buildd/glib2.0-2.40.2/./glib/gmain.c:3729
	# #3 0x00007f7063bc10ec in g_main_context_iteration (context=0x7f70500009b0, may_block=1) at /build/buildd/glib2.0-2.40.2/./glib/gmain.c:3795
	# #4 0x00007f706534d149 in QEventDispatcherGlib::processEvents (this=0x7f70500008e0, flags=...) at kernel/qeventdispatcher_glib.cpp:418
	# #5 0x00007f70652d0f1e in QEventLoop::processEvents (this=0x7f7057df8e10, flags=...) at kernel/qeventloop.cpp:128
	# #6 0x00007f70652d11df in QEventLoop::exec (this=0x7f7057df8e10, flags=...) at kernel/qeventloop.cpp:204
	# #7 0x00007f70650558e0 in QThread::exec (this=0x2732370) at thread/qthread.cpp:503
	# #8 0x00007f706598c5c5 in QQmlThreadPrivate::run (this=0x2732370) at qml/ftw/qqmlthread.cpp:141
	# #9 0x00007f706505cd9b in QThreadPrivate::start (arg=0x2732370) at thread/qthread_unix.cpp:337
	# #10 0x00007f706b7fc182 in start_thread (arg=0x7f7057df9700) at pthread_create.c:312
	# #11 0x00007f706b52947d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
	# (gdb) thread 4
	# [Switching to thread 4 (Thread 0x7f705ca83700 (LWP 23802))]
	# #0 0x00007f706b51c12d in poll () at ../sysdeps/unix/syscall-template.S:81
	# 81 in ../sysdeps/unix/syscall-template.S
	# (gdb) bt
	# #0 0x00007f706b51c12d in poll () at ../sysdeps/unix/syscall-template.S:81
	# #1 0x00007f7067770b72 in poll (__timeout=-1, __nfds=1, __fds=0x7f705ca82d00) at /usr/include/x86_64-linux-gnu/bits/poll2.h:46
	# #2 _xcb_conn_wait (c=c@entry=0x28a2c60, cond=cond@entry=0x28a2ca0, vector=vector@entry=0x0, count=count@entry=0x0) at ../../src/xcb_conn.c:447
	# #3 0x00007f706777264f in xcb_wait_for_event (c=0x28a2c60) at ../../src/xcb_in.c:622
	# #4 0x00007f705fb3df81 in QXcbEventReader::run (this=0x28b0b90) at qxcbconnection.cpp:1105
	# #5 0x00007f706505cd9b in QThreadPrivate::start (arg=0x28b0b90) at thread/qthread_unix.cpp:337
	# #6 0x00007f706b7fc182 in start_thread (arg=0x7f705ca83700) at pthread_create.c:312
	# #7 0x00007f706b52947d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
	#
	# (This issue is not reproduces in Windows, since Qt 5.4 still uses single
	# threaded rendering there.)

	return exit_code


	if __name__ == "__main__":
	exit_code = main()
	sys.exit(exit_code)