Assertion in AudioPlayHead::TimeSignature

Linux
1

Hi, I faced a crashes in AudioPlayHead::TimeSignature instance, when app/plugin is compiled with -Wp,-D_GLIBCXX_ASSERTIONS flag which is default in Fedora Linux. The purpose of this flag is “Enable lightweight assertions in the C++ standard library, such as bounds checking for the subscription operator on vectors.”

For example in BespokeSynth as the host, when any plugin is added:

/usr/include/c++/13/optional:479: constexpr _Tp& std::_Optional_base_impl<_Tp, _Dp>::_M_get() [with _Tp = juce::AudioPlayHead::TimeSignature; _Dp = std::_Optional_base<juce::AudioPlayHead::TimeSignature, true, true>]: Assertion 'this->_M_is_engaged()' failed.

#0  0x00007ffff70949ec in __pthread_kill_implementation () from /lib64/libc.so.6
#1  0x00007ffff7041176 in raise () from /lib64/libc.so.6
#2  0x00007ffff7028917 in abort () from /lib64/libc.so.6
#3  0x00007ffff74df520 in std::__glibcxx_assert_fail(char const*, int, char const*, char const*) () from /lib64/libstdc++.so.6
#4  0x0000000000c88169 in std::_Optional_base_impl<juce::AudioPlayHead::TimeSignature, std::_Optional_base<juce::AudioPlayHead::TimeSignature, true, true> >::_M_get (this=0x7fffeddff404)
    at /usr/include/c++/13/optional:479
#5  0x0000000000c87d3e in std::optional<juce::AudioPlayHead::TimeSignature>::operator-> (this=0x7fffeddff404) at /usr/include/c++/13/optional:968
#6  0x0000000000c8795c in juce::Optional<juce::AudioPlayHead::TimeSignature>::operator-> (this=0x7fffeddff404) at /usr/include/JUCE-7.0.9/modules/juce_core/containers/juce_Optional.h:126
#7  0x0000000000c86d56 in VSTPlayhead::getPosition (this=0x3085ed8) at /home/kv/src/PFM/BespokeSynth/Source/VSTPlayhead.cpp:37
#8  0x0000000000fa1c2d in juce::VSTPluginInstance::processAudio<float> (this=0xa0a5ba0, buffer=..., midiMessages=..., tmpBuffer=..., channelBuffer=..., processBlockBypassedCalled=false)
    at /usr/include/JUCE-7.0.9/modules/juce_audio_processors/format_types/juce_VSTPluginFormat.cpp:2345
#9  0x0000000000f5b6b1 in juce::VSTPluginInstance::processBlock (this=0xa0a5ba0, buffer=..., midiMessages=...)
    at /usr/include/JUCE-7.0.9/modules/juce_audio_processors/format_types/juce_VSTPluginFormat.cpp:1439
#10 0x0000000000c8ffb1 in VSTPlugin::Process (this=0x30856c0, time=13539.666666665824) at /home/kv/src/PFM/BespokeSynth/Source/VSTPlugin.cpp:777
#11 0x00000000006ca570 in ModularSynth::AudioOut (this=0x2271b08, output=0x7fffe9660880, bufferSize=128, nChannels=2) at /home/kv/src/PFM/BespokeSynth/Source/ModularSynth.cpp:2023
#12 0x00000000006839d1 in MainContentComponent::audioDeviceIOCallbackWithContext (this=0x22715c0, inputChannelData=0x0, numInputChannels=0, outputChannelData=0x7fffe9660880, 
    numOutputChannels=2, numSamples=128, context=...) at /home/kv/src/PFM/BespokeSynth/Source/MainComponent.cpp:172
#13 0x0000000000e02e37 in juce::AudioDeviceManager::audioDeviceIOCallbackInt (this=0x2271780, inputChannelData=0x0, numInputChannels=0, outputChannelData=0x7fffe9660880, 
    numOutputChannels=2, numSamples=128, context=...) at /usr/include/JUCE-7.0.9/modules/juce_audio_devices/audio_io/juce_AudioDeviceManager.cpp:1010
#14 0x0000000000e11dea in juce::AudioDeviceManager::CallbackHandler::audioDeviceIOCallbackWithContext (this=0x2270010, ins=0x0, numIns=0, outs=0x7fffe9660880, numOuts=2, numSamples=128, 
    context=...) at /usr/include/JUCE-7.0.9/modules/juce_audio_devices/audio_io/juce_AudioDeviceManager.cpp:79
#15 0x0000000000df82cc in juce::(anonymous namespace)::ALSAThread::run (this=0x7fffe95f2d40) at /usr/include/JUCE-7.0.9/modules/juce_audio_devices/native/juce_ALSA_linux.cpp:714
#16 0x0000000000d5dff3 in juce::Thread::threadEntryPoint (this=0x7fffe95f2d40) at /usr/include/JUCE-7.0.9/modules/juce_core/threads/juce_Thread.cpp:98
#17 0x0000000000d5e0cd in juce::juce_threadEntryPoint (userData=0x7fffe95f2d40) at /usr/include/JUCE-7.0.9/modules/juce_core/threads/juce_Thread.cpp:120
#18 0x0000000000d8479e in operator() (__closure=0x0, userData=0x7fffe95f2d40) at /usr/include/JUCE-7.0.9/modules/juce_core/native/juce_Threads_linux.cpp:40
#19 0x0000000000d847c2 in _FUN () at /usr/include/JUCE-7.0.9/modules/juce_core/native/juce_Threads_linux.cpp:43
#20 0x00007ffff7092bb2 in start_thread () from /lib64/libc.so.6
#21 0x00007ffff711400c in clone3 () from /lib64/libc.so.6
2

Just … imho, enabling GLIBCXX_ASSERTIONS adds overhead that plugin developers, seeking maximum performance, would probably prefer to avoid, which is why I’d suggest you just build your plugins without it enabled.

3

Based on the stack trace, this looks like a bug in BespokeSynth. VSTPlayhead is a custom type that implements getPosition. I’d recommend looking at the implementation of this function to see whether it’s accessing a disengaged Optional instance.

4

@anon48770766 yes, I disabled this for Fedora builds
@reuk as there is the same crash for Vaporizer2 I thought it’s in JUCE somewhere. I’ll try to find where it goes wrong in the Bespoke’s code.