# Error message running Csound with Python and PyQt6 **URL:** \ **Category:** General\ **Created:** [August 30, 2023, 6:16pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324 "2023-08-30T18:16:27Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![JasonHallen](https://forum.csound.com/user_avatar/forum.csound.com/jasonhallen/32/32_2.png) [@JasonHallen](https://forum.csound.com/u/JasonHallen)\ **Post date:** [August 30, 2023, 6:16pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/1 "2023-08-30T18:16:27Z")
Hi everyone, I’m doing a project where I’m controlling Csound with ctcsound and using PyQt6 to build the GUI. It’s a real-time improvisation system. I’m on a 2021 14" MacBook Pro with the M1 Pro chip running macOS 13.4.1. On rare occasions my program crashes and I get the error message below. While it doesn’t happen often (maybe once every 100 times I run the program) it would be pretty bad if it happened while performing live. Can anyone help me interpret this error message and suggest what might be wrong? I’m not even sure if this is a Csound, PyQt6, or Python issue. Any help would be appreciated! libc++abi: terminating due to uncaught exception of type std::\_\_1::system\_error: condition\_variable wait failed: Invalid argument backtrace() returned 79 addresses 0 CsoundLib64 0x00000001186618f8 signal\_handler + 52 1 libsystem\_pthread.dylib 0x0000000188b3bc28 pthread\_kill + 288 2 libsystem\_c.dylib 0x0000000188a49ae8 abort + 180 3 libc++abi.dylib 0x0000000188af4b84 \_ZN10\_\_cxxabiv130\_\_aligned\_malloc\_with\_fallbackEm + 0 4 libc++abi.dylib 0x0000000188ae43b4 \_ZL28demangling\_terminate\_handlerv + 320 5 libobjc.A.dylib 0x00000001887bb03c \_ZL15\_objc\_terminatev + 160 6 libc++abi.dylib 0x0000000188af3f48 \_ZSt11\_\_terminatePFvvE + 16 7 libc++abi.dylib 0x0000000188af3eec \_ZSt9terminatev + 56 8 QtCore 0x0000000101a47470 \_ZN10QSemaphore7acquireEi + 80 9 QtGui 0x00000001088a3890 \_ZN20QGenericUnixServices19setApplicationBadgeEx + 157760 10 QtGui 0x00000001085cc81c \_ZN18QRasterPaintEngine9drawRectsEPK5QRecti + 1436 11 QtGui 0x00000001085cdb64 \_ZN18QRasterPaintEngine8fillRectERK6QRectFP9QSpanData + 424 12 QtGui.abi3.so 0x0000000100f956b8 _ZL22meth\_QPainter\_fillRectP7\_objectS0_ + 148 13 python3.11 0x00000001004fb118 cfunction\_call + 96 14 python3.11 0x00000001005dde34 \_PyEval\_EvalFrameDefault + 196240 15 python3.11 0x0000000100498da4 \_PyFunction\_Vectorcall + 476 16 python3.11 0x000000010049e9e8 method\_vectorcall + 164 17 sip.cpython-311-darwin.so 0x0000000100e99d98 sip\_api\_call\_procedure\_method + 100 18 QtWidgets.abi3.so 0x0000000107e7d044 \_ZN10sipQWidget10paintEventEP11QPaintEvent + 132 19 QtWidgets 0x00000001091ce330 \_ZN7QWidget5eventEP6QEvent + 132 20 QtWidgets.abi3.so 0x0000000107e7e114 \_ZN10sipQWidget5eventEP6QEvent + 224 21 QtWidgets 0x0000000109184fec \_ZN19QApplicationPrivate13notify\_helperEP7QObjectP6QEvent + 272 22 QtWidgets 0x0000000109186994 \_ZN12QApplication6notifyEP7QObjectP6QEvent + 3396 23 QtWidgets.abi3.so 0x0000000107e66548 \_ZN15sipQApplication6notifyEP7QObjectP6QEvent + 248 24 QtCore 0x00000001018d3f88 \_ZN16QCoreApplication15notifyInternal2EP7QObjectP6QEvent + 292 25 QtWidgets 0x00000001091c144c \_ZN14QWidgetPrivate10drawWidgetEP12QPaintDeviceRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 3312 26 QtWidgets 0x00000001091c8adc \_ZN14QWidgetPrivate22paintSiblingsRecursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 864 27 QtWidgets 0x00000001091c154c \_ZN14QWidgetPrivate10drawWidgetEP12QPaintDeviceRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 3568 28 QtWidgets 0x00000001091c8adc \_ZN14QWidgetPrivate22paintSiblingsRecursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 864 29 QtWidgets 0x00000001091c154c \_ZN14QWidgetPrivate10drawWidgetEP12QPaintDeviceRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 3568 30 QtWidgets 0x00000001091c8adc \_ZN14QWidgetPrivate22paintSiblingsRecursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 864 31 QtWidgets 0x00000001091c154c \_ZN14QWidgetPrivate10drawWidgetEP12QPaintDeviceRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 3568 32 QtWidgets 0x00000001091c8adc \_ZN14QWidgetPrivate22paintSiblingsRecursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 864 33 QtWidgets 0x00000001091c154c \_ZN14QWidgetPrivate10drawWidgetEP12QPaintDeviceRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 3568 34 QtWidgets 0x00000001091c8adc \_ZN14QWidgetPrivate22paintSiblingsRecursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 864 35 QtWidgets 0x00000001091c89cc \_ZN14QWidgetPrivate22paintSiblingsRecursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 592 36 QtWidgets 0x00000001091c89cc \_ZN14QWidgetPrivate22paintSiblingsRecursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 592 37 QtWidgets 0x00000001091c89cc \_ZN14QWidgetPrivate22paintSiblingsRecursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 592 38 QtWidgets 0x00000001091c89cc \_ZN14QWidgetPrivate22paintSiblingsRecursiveEP12QPaintDeviceRK5QListIP7QObjectEiRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 592 39 QtWidgets 0x00000001091c154c \_ZN14QWidgetPrivate10drawWidgetEP12QPaintDeviceRK7QRegionRK6QPoint6QFlagsINS\_14DrawWidgetFlagEEP8QPainterP21QWidgetRepaintManager + 3568 40 QtWidgets 0x00000001091dec34 \_ZN21QWidgetRepaintManager13paintAndFlushEv + 3904 41 QtWidgets 0x00000001091deeb8 \_ZN21QWidgetRepaintManager4syncEv + 252 42 QtWidgets 0x00000001091ce7d0 \_ZN7QWidget5eventEP6QEvent + 1316 43 QtWidgets.abi3.so 0x0000000107e7e114 \_ZN10sipQWidget5eventEP6QEvent + 224 44 QtWidgets 0x0000000109184fec \_ZN19QApplicationPrivate13notify\_helperEP7QObjectP6QEvent + 272 45 QtWidgets 0x0000000109186994 \_ZN12QApplication6notifyEP7QObjectP6QEvent + 3396 46 QtWidgets.abi3.so 0x0000000107e66548 \_ZN15sipQApplication6notifyEP7QObjectP6QEvent + 248 47 QtCore 0x00000001018d3f88 \_ZN16QCoreApplication15notifyInternal2EP7QObjectP6QEvent + 292 48 QtCore 0x00000001018d5238 \_ZN23QCoreApplicationPrivate16sendPostedEventsEP7QObjectiP11QThreadData + 1428 49 libqcocoa.dylib 0x000000011ed03268 qt\_plugin\_instance + 51964 50 libqcocoa.dylib 0x000000011ed03d40 qt\_plugin\_instance + 54740 51 CoreFoundation 0x0000000188c1a63c **CFRUNLOOP\_IS\_CALLING\_OUT\_TO\_A\_SOURCE0\_PERFORM\_FUNCTION** + 28 52 CoreFoundation 0x0000000188c1a5d0 \_\_CFRunLoopDoSource0 + 176 53 CoreFoundation 0x0000000188c1a340 \_\_CFRunLoopDoSources0 + 244 54 CoreFoundation 0x0000000188c18f48 \_\_CFRunLoopRun + 828 55 CoreFoundation 0x0000000188c184b8 CFRunLoopRunSpecific + 612 56 HIToolbox 0x0000000192462c40 RunCurrentEventLoopInMode + 292 57 HIToolbox 0x0000000192462a7c ReceiveNextEventCommon + 648 58 HIToolbox 0x00000001924627d4 \_BlockUntilNextEventMatchingListInModeWithFilter + 76 59 AppKit 0x000000018be39d44 \_DPSNextEvent + 636 60 AppKit 0x000000018be38ee0 -[NSApplication(NSEvent) \_nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 716 61 AppKit 0x000000018be2d344 -[NSApplication run] + 464 62 libqcocoa.dylib 0x000000011ed02644 qt\_plugin\_instance + 48856 63 QtCore 0x00000001018dd8fc \_ZN10QEventLoop4execE6QFlagsINS\_17ProcessEventsFlagEE + 532 64 QtCore 0x00000001018d4614 \_ZN16QCoreApplication4execEv + 112 65 QtWidgets.abi3.so 0x0000000107f69cb0 _ZL22meth\_QApplication\_execP7\_objectS0_ + 96 66 python3.11 0x00000001004fb118 cfunction\_call + 96 67 python3.11 0x00000001005dde34 \_PyEval\_EvalFrameDefault + 196240 68 python3.11 0x00000001005ab53c \_PyEval\_Vector + 464 69 python3.11 0x00000001005ab2dc PyEval\_EvalCode + 248 70 python3.11 0x0000000100644610 run\_mod + 184 71 python3.11 0x00000001006443dc pyrun\_file + 148 72 python3.11 0x0000000100643e08 \_PyRun\_SimpleFileObject + 268 73 python3.11 0x0000000100643780 \_PyRun\_AnyFileObject + 216 74 python3.11 0x00000001006672ac pymain\_run\_file\_obj + 260 75 python3.11 0x0000000100666bd4 pymain\_run\_file + 72 76 python3.11 0x00000001006663d4 Py\_RunMain + 1328 77 python3.11 0x0000000100430c00 main + 56 78 dyld 0x00000001887e3f28 start + 2236 Thanks! Jason ---
**Author:** ![tarmo](https://forum.csound.com/letter_avatar_proxy/v4/letter/t/c37758/32.png) [@tarmo](https://forum.csound.com/u/tarmo)\ **Post date:** [August 30, 2023, 6:50pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/2 "2023-08-30T18:50:09Z")
Hi! My guess is that it is a threading problem. Do you use csoundPerformanceThread or create your own thread or execute somehow Csound in the Qt event loop? How do you call Csound functions? I have worked much with C++ and QML in Qt but not much with Python. I guess there is is similar signal and slot connection system? Signals and slots should be the right way to connect your UI (or other components) with Csound funtions. Can you attach the Python code? Otherwise it is hard to guess. The reason may be also elsewhere… tarmo Kontakt Jason Hallen via The Csound Community (\<[noreply@forum.csound.com](mailto:noreply@forum.csound.com)\>) kirjutas kuupäeval K, 30. august 2023 kell 21:26: ---
**Author:** ![JasonHallen](https://forum.csound.com/user_avatar/forum.csound.com/jasonhallen/32/32_2.png) [@JasonHallen](https://forum.csound.com/u/JasonHallen)\ **Post date:** [August 30, 2023, 7:32pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/3 "2023-08-30T19:32:29Z")
Thanks for the response, Tarmo. I’m using `ctcsound.CsoundPerformanceThread` to run the Csound thread. Yes, PyQt has the same signals and slots connection system as in Qt, though so far I’m only using it to send changes in a couple GUIs widgets to Csound with `.setControlChannel`. The way I’m reading channels from Csound is currently via a `QTimer` loop which reads from a few `.channelPtr`s. I’ve also successfully experimented with 1) using a separate thread in PyQt and 2) using OSC to do communication with Csound, but I’m using `QTimer` for now because it’s so simple and meets my needs. Do you think using the signals/slots system more consistently for all Csound communication might help avoid threading errors? Or perhaps using a separate thread or OSC for Csound communication rather than a `QTimer` loop? I’ve attached the Python code as a .txt file because I can’t upload a .py file. [aya.txt](https://forum.csound.com/uploads/short-url/sUfanFNhYMK6AT2C0fknPvQ0Rh8.txt) (61.1 KB) It’s pretty messy because it’s in early stages of development, but maybe it’ll help. Searching for “csound” in the code will take you to the parts of the code where I’m sending and receiving messages from Csound. I’ve also included the .csd file in case that helps. [aya.csd](https://forum.csound.com/uploads/short-url/lOm7v3zkcgRHifAmmsA6LY3agmm.csd) (2.8 KB) Thanks for your help! Jason ---
**Author:** ![stevenyi](https://forum.csound.com/user_avatar/forum.csound.com/stevenyi/32/4_2.png) [@stevenyi](https://forum.csound.com/u/stevenyi)\ **Post date:** [August 31, 2023, 4:17am UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/4 "2023-08-31T04:17:35Z")
Checking, are you calling csoundInitialize with value (CSOUNDINIT\_NO\_ATEXIT | CSOUNDINIT\_NO\_SIGNAL\_HANDLER)? ---
**Author:** ![JasonHallen](https://forum.csound.com/user_avatar/forum.csound.com/jasonhallen/32/32_2.png) [@JasonHallen](https://forum.csound.com/u/JasonHallen)\ **Post date:** [August 31, 2023, 11:10am UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/5 "2023-08-31T11:10:16Z")
Hi Steven, no I’m not calling `csoundInitialize` with those flags. Should I be? Thanks, Jason ---
**Author:** ![stevenyi](https://forum.csound.com/user_avatar/forum.csound.com/stevenyi/32/4_2.png) [@stevenyi](https://forum.csound.com/u/stevenyi)\ **Post date:** [August 31, 2023, 1:33pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/6 "2023-08-31T13:33:51Z")
Yes, IMO, most every API app should. The signal handlers csound installs are appropriate for the csound CLI app but they can interfere with other signal handlers that get installed by things like Python’s interpreter or Java’s JVM. I don’t know if that is the root cause here (I saw the stack trace mentioned signal\_handler), but I’d suggest trying to put it in and seeing if the problem persists. ---
**Author:** ![stevenyi](https://forum.csound.com/user_avatar/forum.csound.com/stevenyi/32/4_2.png) [@stevenyi](https://forum.csound.com/u/stevenyi)\ **Post date:** [August 31, 2023, 1:34pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/7 "2023-08-31T13:34:30Z")
And to add, do it first thing when your application starts and before doing anything else with Csound like creating a Csound object. ---
**Author:** ![JasonHallen](https://forum.csound.com/user_avatar/forum.csound.com/jasonhallen/32/32_2.png) [@JasonHallen](https://forum.csound.com/u/JasonHallen)\ **Post date:** [August 31, 2023, 1:53pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/8 "2023-08-31T13:53:17Z")
Great, thanks for the suggestion! I’ve added this in, so we’ll see if I get those errors again. Jason ---
**Author:** ![JasonHallen](https://forum.csound.com/user_avatar/forum.csound.com/jasonhallen/32/32_2.png) [@JasonHallen](https://forum.csound.com/u/JasonHallen)\ **Post date:** [September 1, 2023, 5:18am UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/9 "2023-09-01T05:18:38Z")
After adding in the csoundInitialize call at the beginning of the code, I’m now getting this shorter error message when my program crashes. The frequency of the crashing has gone up a lot, around once every 7 times I run the program. **libc++abi: terminating due to uncaught exception of type std::\_\_1::system\_error: condition\_variable wait failed: Invalid argument** It’s no longer producing the very long backtrace report, just this short message. I’m still not sure if this is a macOS/PyQt thing or a Csound thing. Perhaps I’m playing fast and loose with the communication between PyQt and Csound, so I’ll experiment with different ways to improve that. Jason ---
**Author:** ![Cordelia](https://forum.csound.com/user_avatar/forum.csound.com/cordelia/32/279_2.png) [@Cordelia](https://forum.csound.com/u/Cordelia)\ **Post date:** [September 1, 2023, 12:26pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/10 "2023-09-01T12:26:00Z")
> [@stevenyi](#): > > Yes, IMO, most every API app should. The signal handlers csound installs are appropriate for the csound CLI app but they can interfere with other signal handlers that get installed by things like Python’s interpreter or Java’s JVM. I don’t know if that is the root cause here (I saw the stack trace mentioned signal\_handler), but I’d suggest trying to put it in and seeing if the problem persists. Amazing. didnt know taht. ---
**Author:** ![tarmo](https://forum.csound.com/letter_avatar_proxy/v4/letter/t/c37758/32.png) [@tarmo](https://forum.csound.com/u/tarmo)\ **Post date:** [September 1, 2023, 8:36pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/11 "2023-09-01T20:36:51Z")
Hi Jason, I was now able to look at your code. Looks cool! At the first glance I don’t see anything suspicious… It seems right to me how you do it. I tried to run it but could not do it without samples. Some things I suggest you to try: - do not use any audio output (for testing), instead of Coreaudio try -+rtaudio=null If that works, try wiht portaudio or jack - tr bigger buffers (-b and -B options in Csound file) - try longer QTimer update time The problem could be still elsewhere, I cannot tell. As a fallback, Are you a CsoundQt user? Not all, but I believe essential part of the UI could be realized also with the CsoundQt widgets. And if you need more, you could use PythonQt functionality from withing CsoundQt. Last official CsoundQt MacOS build is wihtoug PythonQt support though… See [https://csoundqt.github.io/pages/python.html](https://csoundqt.github.io/pages/python.html) for some information. OR if you are comfortable with html and javascript you can add missing parts of the UI in html. Not sure if it helps… tarmo Kontakt Cordelia via The Csound Community (\<[noreply@forum.csound.com](mailto:noreply@forum.csound.com)\>) kirjutas kuupäeval R, 1. september 2023 kell 15:36: ---
**Author:** ![JasonHallen](https://forum.csound.com/user_avatar/forum.csound.com/jasonhallen/32/32_2.png) [@JasonHallen](https://forum.csound.com/u/JasonHallen)\ **Post date:** [September 2, 2023, 1:46pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/12 "2023-09-02T13:46:47Z")
Thanks very much for taking the time to review the code and send your suggestions, Tarmo! Can you say a little more about why I should not use any audio output for testing? I’m open to that but would appreciate understanding the reasoning. The program does work with `-+rtaudio=null`, but it doesn’t work with `portaudio`. I’ve had problems with `portaudio` on my computer, which is why I’ve been using `coreaudio`. Do you suggest `portaudio` and `jack` because they perform better than `coreaudio`? Trying bigger buffers and update times also sounds good to me. I can keep tweaking them to get a balance of performance and responsiveness. Yes, I’ve been a CsoundQt user in the past. The past couple years I’ve been delving into building my own GUIs in order to have complete control over the programs. I spent a lot of time using JS/HTML/CSS for Csound GUI development but bailed on that because it was getting too complicated (for a novice like me) operating in the browser environment, and PyQt has been a breath of fresh air since then. It’s good to know though that I can return to CsoundQt if I can’t find a way forward with PyQt. Thanks! Jason ---
**Author:** ![tarmo](https://forum.csound.com/letter_avatar_proxy/v4/letter/t/c37758/32.png) [@tarmo](https://forum.csound.com/u/tarmo)\ **Post date:** [September 2, 2023, 5:41pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/13 "2023-09-02T17:41:19Z")
Hi! > The program does work with `-+rtaudio=null` It was a blind guess. I have heard about problems sometimes with Coreaudio. Anyway, seems that your code is fine, the problem is somewhere in communication with the audio driver. Might be that Python is not fast enough sometimes to fulfill some needs, I don’t know. Yes, try with Jack, Joachim Heintz has found that it works the best on MacOS (at least with CsoundQt that is using Csound API as well). And make all buffers bigger and do anything that makes the life of the program easier, later you can breing them down to via trial- and error 🙂 I agree with you - creating a custom GUI with Qt is a good way. Performance wise C++ is of course much quicker. My preferred solution recently is to use QML (Qt Meta Language) for the UI and a C++ class that deals with Csound. Best! tarmo Kontakt Jason Hallen via The Csound Community (\<[noreply@forum.csound.com](mailto:noreply@forum.csound.com)\>) kirjutas kuupäeval L, 2. september 2023 kell 16:56: ---
**Author:** ![JasonHallen](https://forum.csound.com/user_avatar/forum.csound.com/jasonhallen/32/32_2.png) [@JasonHallen](https://forum.csound.com/u/JasonHallen)\ **Post date:** [September 12, 2023, 1:39pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/14 "2023-09-12T13:39:12Z")
Here’s an update in case this helps anyone in the future. The program kept crashing in the same way as in my initial post. I noticed that the backtrace report often suggested that the crash came when the QtGui module was running the `drawText` function. In my GUI there’s an event loop that uses the `drawText` function, and it’s pulling a value from Csound to draw. I wondered if the Csound value couldn’t be pulled in time to draw the text, so I commented out all the `drawText` code. That was a few days ago, and there hasn’t been a crash since. I’m not confident the problem won’t re-emerge, but at least for now the crashing has stopped. I’ve also incorporated Eduardo’s csoundengine to control Csound with Python, and I’m sure his mechanisms for communicating with Csound are more informed and efficient than mine were. That’s probably also helping reduce crashes. Thanks, Jason ---
**Author:** ![JasonHallen](https://forum.csound.com/user_avatar/forum.csound.com/jasonhallen/32/32_2.png) [@JasonHallen](https://forum.csound.com/u/JasonHallen)\ **Post date:** [September 12, 2023, 2:45pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/15 "2023-09-12T14:45:57Z")
Hilariously, after just posting my previous message my program just crashed in the same way again for the first time in a few days. Gotta figure out how these PyQt drawing functions are related to the crashing and whether it involves Csound. Time for more debugging… Jason ---
**Author:** ![eduardomoguillansky](https://forum.csound.com/user_avatar/forum.csound.com/eduardomoguillansky/32/437_2.png) [@eduardomoguillansky](https://forum.csound.com/u/eduardomoguillansky)\ **Post date:** [September 12, 2023, 3:00pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/16 "2023-09-12T15:00:37Z")
I would guess that it is a threading issue. You should not call csound from the gui thread. Instead read any value from csound within a qtimer and put that on a queue. Then when drawing read from that queue. Or do all communication via osc. ---
**Author:** ![JasonHallen](https://forum.csound.com/user_avatar/forum.csound.com/jasonhallen/32/32_2.png) [@JasonHallen](https://forum.csound.com/u/JasonHallen)\ **Post date:** [September 12, 2023, 3:17pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/17 "2023-09-12T15:17:47Z")
Thanks for the tips, Eduardo! I’ll experiment with different ways to read Csound values from outside of the GUI thread. I’ve been able to use QThreads and OSC to read Csound values in separate threads in previous PyQt experiments but was hoping I could keep things simpler for this project. I guess not! Jason ---
**Author:** ![tarmo](https://forum.csound.com/letter_avatar_proxy/v4/letter/t/c37758/32.png) [@tarmo](https://forum.csound.com/u/tarmo)\ **Post date:** [September 12, 2023, 8:04pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/18 "2023-09-12T20:04:56Z")
Hi, I think uou are close - if you have csound running in separate thread, the Qt way would be to send a signal when a value changes from that thread and and connect it to a drawing slot in your UI thread. Tarmo T, 12. september 2023 18:27 Jason Hallen via The Csound Community \<[noreply@forum.csound.com](mailto:noreply@forum.csound.com)\> kirjutas: ---
**Author:** ![JasonHallen](https://forum.csound.com/user_avatar/forum.csound.com/jasonhallen/32/32_2.png) [@JasonHallen](https://forum.csound.com/u/JasonHallen)\ **Post date:** [September 13, 2023, 1:13pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/19 "2023-09-13T13:13:53Z")
Hi all, I’ve changed the code to only read Csound data from a separate QThread and send it to the GUI thread via signals/slots. However, I’m still getting crashes. I think I’m misunderstanding how to manage concurrency and thread communication. If I explain what I’m doing can you let me know what I’m doing wrong? **Threads** 1. The main GUI thread is a PyQt QWidget. 2. Csound is run in a performance thread managed by `csoundengine.Engine().session()`. 3. Csound data is read in a separate QThread. **Reading Csound Data** The QThread reads data from Csound. Specifically, the instruments defined in the Session use Csound tables to read/write the p-arguments, so the QThread reads the data from these tables with `.get()`. The data is sent from the QThread to the GUI thread via signals/slots. The slots that receive the data in the GUI trigger updates to the widgets. Here’s where I’m wondering if I’m doing it wrong. In order to know what Csound data to read in the QThread, I pass the main GUI thread object (`main`) into the QThread upon instantiation. It looks like this: ``` class WorkerAPI(QObject): '''Runs a loop in a separate thread that reads Csound data.''' playback = pyqtSignal(tuple) main_volume = pyqtSignal(float) def __init__ (self, main): super(WorkerAPI, self). __init__ () self.main = main def run(self): self._active = True while self._active: for track in self.main.tracks_panel.track_list: if track.synth is not None: playback_position = track.synth.get("kplayback_position") if playback_position is not None: self.playback.emit((track, playback_position)) meter_maximum = self.main.mixer.get("kmeter_maximum") self.main_volume.emit(meter_maximum) time.sleep(0.05) ``` Does it defeat the purpose of using a QThread to read Csound data if I’m still using the objects defined in the main GUI thread (i.e. `self.main.tracks_panel.track_list` and `self.main.mixer`) within the QThread? How else would I approach this? I’m struggling to know how to fully isolate the Csound communication from the main GUI. **Sending Csound Data** Control signals are sent from the GUI thread to Csound within the GUI thread using `synth.set()`. I was thinking it’s okay to send control signals from the GUI thread because timing isn’t important as long as Csound eventually receives the control signal and the GUI thread is not awaiting a response from `synth.set()`. But maybe I should also be sending all control signals from the QThread? Thanks as always for your guidance! Jason ---
**Author:** ![JasonHallen](https://forum.csound.com/user_avatar/forum.csound.com/jasonhallen/32/32_2.png) [@JasonHallen](https://forum.csound.com/u/JasonHallen)\ **Post date:** [September 13, 2023, 9:09pm UTC](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324/20 "2023-09-13T21:09:16Z")
I’m exploring a new solution. Will report back soon. [Next page](https://forum.csound.com/t/error-message-running-csound-with-python-and-pyqt6/1324.md?page=2)