On 7/16/2007 2:36 PM, Phil Thompson wrote:
On Tuesday 10 July 2007 5:42 pm, Giovanni Bajo wrote:
Hi Phil,
a little crasher:
==============================================
from PyQt4.QtCore import *
app = QCoreApplication([])
for i in range(300):
print i
w1 = QObject(None)
w2 = QObject(None)
print id(w1), id(w2)
QObject.connect(w2, SIGNAL("CRASH"), w1, SIGNAL("CRASH"))
w2.emit(SIGNAL("CRASH"))
==============================================
This snippet segfaults on both Linux and Windows with recent SIP/PyQt
versions. The segfault is due to an infinite loop, that can be aborted
before it smashes the stack with this patch:
Index: sip/QtCore/qobject.sip
===================================================================
--- sip/QtCore/qobject.sip (revision 13422)
+++ sip/QtCore/qobject.sip (working copy)
@@ -955,9 +955,15 @@
// wrapped tuple of Python argument objects.
void PyQtProxy::pysignal(const PyQt_PyObject &pyargs)
{
+ static int recursion = 0;
+
void *_a[] = {0, const_cast<void *>(reinterpret_cast<const void
*>(&pyargs))};
+ recursion += 1;
+ if (recursion == 5)
+ abort();
QMetaObject::activate(this, &staticMetaObject, 0, _a);
+ recursion -= 1;
}
I *think* it's related to an instance's address being reused by Python
before PyQt has stopped bookkeeping its existence. On my computer, this
is the output:
0
9193416 9193488
1
9193560 9193416
2
9193488 9193560
[segfault]
As you can see, the instance address is reused by Python, and this
somewhat triggers the infinite loop in dispatching the signal (the
signal becomes connected to the same instance emitting it).
This will be fixed in tonight's PyQt snapshot.
The proxy created to handle the signal was being incorrectly reused by a new
QObject created at the same address as the one the proxy was created for.
Because there is no event processing going on, the proxy was not getting
deleted - because it was waiting for a deleteLater() to be acted on.
Thanks! Don't you have a gift for the impatients? :)
--
Giovanni Bajo
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