Experimental Physics and
Industrial Control System

"Daykin, Evan via Tech-talk" <tech-talk at aps.anl.gov> · Tue, 3 May 2022 16:52:42 +0000

Thanks, that was the problem. Setting copyArray=true makes the issue go away. Are there any adverse side-effects of doing so?

-----Original Message-----
From: Michael Davidsaver <mdavidsaver at gmail.com> 
Sent: Tuesday, May 3, 2022 12:10 PM
To: Daykin, Evan <daykin at frib.msu.edu>
Cc: Mark Rivers <rivers at cars.uchicago.edu>; tech-talk at aps.anl.gov
Subject: Re: NDArrayPool:reserve ERROR, reference count = 0, should be = 1

[EXTERNAL] This email originated from outside of FRIB

On 5/3/22 08:52, Daykin, Evan via Tech-talk wrote:

> Hm… I am not explicitly calling release() anywhere. This is my processCallbacks function-  everything else in my plugin, AFAIK, doesn’t access any shared resources.

I have half a memory that NDPluginDriver::endProcessCallbacks() "steals"* a reference

to the NDArray when copyArray=false.

* https://docs.python.org/3/c-api/intro.html#reference-count-details

> void NDPluginTemperature::processCallbacks(NDArray *pArray){

> 

>      static const char *functionName = "processCallbacks";

> 

>      NDArrayInfo_t arrayInfo;

> 

>      if(pArray->dataType != NDUInt16){

> 

>          asynPrint(this->pasynUserSelf, ASYN_TRACE_ERROR,

> 

>          "%s:%s: Only UInt16 supported.", driverName, functionName);

> 

>          return;

> 

>      }

> 

>      std::string lastCalFileName = this->calibrationFileName;

> 

>      getStringParam(this->calibrationFileNameIdx, this->calibrationFileName);

> 

>      if(this->calibrationFileName != lastCalFileName){

> 

>          this->processCalibrationFile();

> 

>      }

> 

>      int arrayCallbacks;

> 

>      getIntegerParam(NDArrayCallbacks, &arrayCallbacks);

> 

>      if(arrayCallbacks==1){

> 

>          epicsTimeStamp before;

> 

>          epicsTimeGetCurrent(&before);

> 

>          NDPluginDriver::beginProcessCallbacks(pArray);

> 

>          this->pNDArrayPool->convert(pArray,&(this->inputArray), NDUInt16);

> 

>          if(NULL == this->outputArray){

> 

>              this->pNDArrayPool->convert(pArray,&(this->outputArray),NDUInt16);

> 

>          }

> 

>          //unlock while the plug-and-chug happens. No shared resources are accessed at this time.

> 

>          inputArray->getInfo(&arrayInfo);

> 

>          this->unlock();

> 

>          this->doTemperatureConversion(this->inputArray, this->outputArray, &arrayInfo);

> 

>          this->lock();

> 

>          setIntegerParam(NDArraySizeX, (int)outputArray->dims[arrayInfo.xDim].size);

> 

>          setIntegerParam(NDArraySizeY, (int)outputArray->dims[arrayInfo.yDim].size);

> 

>         epicsTimeStamp after;

> 

>          epicsTimeGetCurrent(&after);

> 

>          double delta = epicsTimeDiffInSeconds(&after, &before);

> 

>          cout<<"Took "<<delta<<" s"<<endl;

> 

>          setDoubleParam(runTimeIdx, delta);

> 

>          NDPluginDriver::endProcessCallbacks(outputArray, false, true);

> 

>          callParamCallbacks();

> 

>      }

> 

> }

> 

> *From:*Mark Rivers <rivers at cars.uchicago.edu>

> *Sent:* Tuesday, May 3, 2022 11:37 AM

> *To:* tech-talk at aps.anl.gov; Daykin, Evan <daykin at frib.msu.edu>

> *Subject:* Re: NDArrayPool:reserve ERROR, reference count = 0, should be = 1

> 

> *[EXTERNAL] This email originated from outside of FRIB*

> 

> Hi Evan,

> 

> That error probably means you have called NDArray::release() on an array whose reference count is already 0.

> 

> Most plugins don't need to call release() because it is handled in the base class NDPluginDriver::endProcessCallbacks().

> 

> Mark

> 

> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

> 

> *From:*Tech-talk <tech-talk-bounces at aps.anl.gov <mailto:tech-talk-bounces at aps.anl.gov>> on behalf of Daykin, Evan via Tech-talk <tech-talk at aps.anl.gov <mailto:tech-talk at aps.anl.gov>>

> *Sent:* Tuesday, May 3, 2022 10:20 AM

> *To:* tech-talk at aps.anl.gov <mailto:tech-talk at aps.anl.gov> <tech-talk at aps.anl.gov <mailto:tech-talk at aps.anl.gov>>

> *Subject:* NDArrayPool:reserve ERROR, reference count = 0, should be = 1

> 

> Hi,

> 

> I am hoping there’s an AreaDetector plugin maven here…

> 

> 

> I have written a small AD plugin intended to convert our raw camera images into a temperature heatmap, based on a calibrated gain, emissivity and exposure time. To test it, I set up a SimDetector in “peak” mode. I connect my plugin to this simDetector image. I can successfully capture and convert 3 frames. On the fourth frame, my test dies with the following error. Are there any common pitfalls that might cause this?

> 

> NDArray.uniqueId=1

> 

> Do temperature conversion start

> 

> Took 0.0937809 s

> 

> NDArray.uniqueId=2

> 

> Do temperature conversion start

> 

> Took 0.0655851 s

> 

> NDArray.uniqueId=3

> 

> Do temperature conversion start

> 

> Took 0.0642867 s

> 

> NDArray.uniqueId=4

> 

> NDArrayPool:reserve ERROR, reference count = 0, should be >= 1, pArray=0x7f453c001d80

> 

> Thread SimDetTask (0x5621bbbb0c80) can't proceed, suspending.

> 

> Dumping a stack trace of thread 'SimDetTask':

> 

> [    0x7f45538ffab3]: /lib/x86_64-linux-gnu/libCom.so.3.15.9(epicsStackTrace+0x73)

> 

> [    0x7f45538f0216]: /lib/x86_64-linux-gnu/libCom.so.3.15.9(cantProceed+0xc6)

> 

> [    0x7f4553197b08]: /lib/x86_64-linux-gnu/libADBase.so.3.11(_ZN11NDArrayPool7reserveEP7NDArray+0x78)

> 

> [    0x7f455305db37]: /lib/x86_64-linux-gnu/libNDPlugin.so.3.11(_ZN14NDPluginDriver21beginProcessCallbacksEP7NDArray+0x367)

> 

> [    0x7f455375df1e]: /home/daykin/git/areadetector-temperature/lib/linux-x86_64/libNDPluginTemperature.so(_ZN19NDPluginTemperature16processCallbacksEP7NDArray+0xae)

> 

> [    0x7f455305dd53]: /lib/x86_64-linux-gnu/libNDPlugin.so.3.11(_ZN14NDPluginDriver14driverCallbackEP8asynUserPv+0x1d3)

> 

> [    0x7f4553851155]: /lib/x86_64-linux-gnu/libasyn.so.4.38(_ZN14asynPortDriver25doCallbacksGenericPointerEPvii+0x1f5)

> 

> [    0x7f4553809974]: /usr/lib/epics/lib/linux-x86_64/libsimDetector.so(_ZN11simDetector7simTaskEv+0x4e4)

> 

> [    0x7f45538fa0bb]: /lib/x86_64-linux-gnu/libCom.so.3.15.9(epicsSnprintf+0x7bb)

> 

> [    0x7f4553387ea7]: /lib/x86_64-linux-gnu/libpthread.so.0(start_thread+0xd7)

> 

> [    0x7f455349edef]: /lib/x86_64-linux-gnu/libc.so.6(clone+0x3f)

> 

> *Evan Daykin*

> 

> Controls Engineer

> 

> Facility for Rare Isotope Beams

> 

> Michigan State University

> 

> 640 South Shaw Lane

> 

> East Lansing, MI 48824, USA

> 

> Tel. 517-908-7678

> 

> Email: daykin at frib.msu.edu <mailto:mccausey at frib.msu.edu>

> 

> 	

> 

> *cid:[email protected]*

> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System