id	summary	reporter	owner	description	type	status	priority	milestone	component	version	severity	resolution	keywords	cc	mlocked
12909	mythfrontend crashes with SIGSEGV in code called from QImage::Load	roger@…	stuartm	"mythfrontend randomly crashes on startup when a lot of images are being loaded into the image cache. Analysis of the crash shows that QImage::Load is being called on multiple threads. The QImage class is specifically marked in the Qt docs as re-entrant but not thread-safe.

The crashes usually occur in QFactoryLoader::instance but can occur elsewhere in QT. The common factor is they all root at ImageLoader::LoadImage in mythuiimage.cpp.

Here is a sample stack trace. The SIGSEGV occurs when qt tries to call a plugin that has been unloaded from memory.


{{{

(gdb) bt
#0  0x00007f90f8142d50 in ?? ()
#1  0x00007f91123f8375 in QFactoryLoader::instance (
    this=this@entry=0x7f9112ea5240 <_ZZN12_GLOBAL__N_112Q_QGS_loader13innerFunctionEvE6holder>, index=index@entry=0) at plugin/qfactoryloader.cpp:259
#2  0x00007f9112ab059d in createReadHandlerHelper (device=0x7f90b800e9c0, 
    format=..., autoDetectImageFormat=<optimized out>, 
    ignoresFormatAndExtension=<optimized out>) at image/qimagereader.cpp:318
#3  0x00007f9112ab1449 in QImageReaderPrivate::initHandler (
    this=0x7f90b8042540) at image/qimagereader.cpp:617
#4  0x00007f9112ab2782 in QImageReader::read (this=0x7f90bfffe500, 
    image=0x7f90bfffe4a0) at image/qimagereader.cpp:1276
#5  0x00007f9112ab2814 in QImageReader::read (this=this@entry=0x7f90bfffe500)
    at image/qimagereader.cpp:1244
#6  0x00007f9112a950e3 in QImage::load (this=0x7f90b800eec0, fileName=..., 
    format=<optimized out>) at image/qimage.cpp:3206
#7  0x00007f91141e1b44 in MythImage::Load (this=0x7f90b800e920, filename=...)
    at mythimage.cpp:364
#8  0x00007f9114209b13 in MythUIHelper::LoadCacheImage (this=0x1bc5050, 
    srcfile=..., label=..., painter=0x1c283c0, cacheMode=kCacheNormal)
    at mythuihelper.cpp:1672 (This is slightly off because I put some debug in}
#9  0x00007f911422a9fc in ImageLoader::LoadImage (painter=0x1c283c0, 
    imProps=..., cacheMode=kCacheNormal, parent=0x20e7360, 
    aborted=@0x7f90bfffeb4f: false, imageReader=0x0) at mythuiimage.cpp:273
#10 0x00007f911422c255 in ImageLoadThread::run (this=0x20e7a60)
    at mythuiimage.cpp:553
#11 0x00007f9114646961 in MPoolThread::run (this=0x1ebe220)
    at mthreadpool.cpp:140
#12 0x00007f9114642e70 in MThreadInternal::run (this=0x1cd8210)
    at mthread.cpp:79
#13 0x00007f911222b84e in QThreadPrivate::start (arg=0x1cd8210)
    at thread/qthread_unix.cpp:331
#14 0x00007f9111f706fa in start_thread (arg=0x7f90bffff700)
    at pthread_create.c:333
#15 0x00007f9111405b5d in clone ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

}}}
I can usually get this crash within four or five reboots and autostarts on my shuttle frontend box. Putting a 60 second delay in the mythfrontend wrapper script alleviates it considerably.

This problem seems to have been around for some time. There are one or two expired tickets on the mythbuntu bug tracker that seem to have similar symptoms.
"	Bug Report - Crash	closed	major	29.0	MythTV - User Interface Library	0.28.0	high	Fixed			0