c++ - Matlab/C++ : segmentation fault on parallel computing with C++ Mex persistent objects (cannot convert handle)

coder 2024-02-21 原文

本帖引用:

[1] http://www.mathworks.com/matlabcentral/newsreader/view_thread/278243 “使 C++ 对象在 mex 调用之间持久化，并且健壮。”

[2] MATLAB parfor and C++ class mex wrappers (copy constructor required?) “MATLAB parfor 和 C++ 类 mex 包装器(需要复制构造函数？)”

我成功地实现了一个 Matlab/C++ 接口(interface)，基于 [1] 上提出的方法。
无论如何，我在尝试将系统与 Matlab 并行计算一起使用时遇到了麻烦。

在 MEX 接口(interface)中尝试在 matlab 句柄和 C++ 指针之间进行转换时，发生在我身上的是段错误。

为了更清楚，我将回顾一下 [1] 中提出的结构。
系统中有三个文件，采用这种通信方案:

[myInterface.m] <--> [myMexInterface.cpp] <--> [myClass.cpp]

在哪里

myInterface.m 是一个 matlab 类

myMexInterface.cpp 是 C++ (mex) 函数

myClass.cpp 是一个 C++ (mex) 类

该系统的使用分为两个阶段:

build :
创建了一个 matlab 对象 myInterface。这会导致调用 myMexInterface.mexa64，从而调用 C++ myClass 对象的创建。 myClass 的 C++ 指针通过 myMexInterface.mexa64 发送回 myInterface，它存储它以供进一步使用。特别是，myMexInterface.mexa64 将 myClass 的 C++ 指针转换为 matlab 句柄。

使用 matlab 中的 C++ 类:
myInterface 向客户端提供方法，这些方法通过 myMexInterface.mexa64 调用对象 myClass 上的函数。在此阶段，在构造阶段从 myInterface 存储的句柄对于 myMexInterface.mexa64 是必需的，以便在正确的 C++ 对象上调用函数。当然，在这个阶段 myMexInterface.mexa64 进行了反向转换，从 Matlab 句柄到 C++ 指针。

在我的实现中，它在单线程中工作，在从句柄到指针的转换过程中出现段错误错误。
我特别想关注 myMexInterface.cpp。
要执行的命令通过字符串作为第一个参数传递，而(对于第二阶段操作)第二个参数可能是与该接口(interface)关联的 C++ 对象相关的 matlab 句柄。

#include "mex.h"
#include "class_handle.hpp"

    CLASS void myMexInterface(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
{
  if (!strcmp("new", cmd)) {
    // ...
    plhs[0] = convertPtr2Mat<myClass>(new myClass());
  }
  if (!strcmp("delete", cmd)) {
    // ...
    destroyObject<myClass>(prhs[1]);   
  }
  // Get the class instance pointer from the second input
  cout << " trying to convert handle..."; 
  myClass *myClass_instanceAddress = convertMat2Ptr<myClass>(prhs[1]); // SEGMENTATION FAULT ON MULTI CORE!!!
  cout << "   success in handle conversion. \n"; 
  if (!strcmp("aFunction", cmd)) {
    myClass_instanceAddress->aFunction();
  }
  // .. other functions
}

生成段错误的函数 convertMat2Pt 来自包含 class_handle.hpp，这是 [1] 中提出的解决方案的一部分。
特别是 class_handle.hpp 中的函数，其中段错误是 convertMat2HandlePtr:

template<class base> class class_handle

// ...

template<class base> inline class_handle<base> *convertMat2HandlePtr(const mxArray *in)
{
  if (mxGetNumberOfElements(in) != 1 || mxGetClassID(in) != mxUINT64_CLASS || mxIsComplex(in))
      mexErrMsgTxt("Input must be a real uint64 scalar.");

  std::cout << "class_handle: trying to cast \n";
  class_handle<base> *ptr = reinterpret_cast<class_handle<base> *>(*((uint64_t *)mxGetData(in))); // SEGMENTATION FAULT ON MULTI CORE!!!
  if (!ptr->isValid())
    mexErrMsgTxt("Handle not valid.");
  return ptr;
}

template<class base> inline base *convertMat2Ptr(const mxArray *in)
{
  return convertMat2HandlePtr<base>(in)->ptr();
}

// ...

实际上我不清楚那个 Actor 到底发生了什么，所以我无法进行更深入的分析。
我能想象的是，由于某种原因，Matlab 并行计算与之前创建的 C++ 对象产生了不一致。

生成段错误的matlab客户端函数如下:

myInterface = myMexInterface();
matlabpool open local 1   
out = myModelInterf.aFunction()
disp('                               Now starting parfor ***');
parfor i = 1:1
  out = myModelInterf.aFunction()
end

请注意，为了简化情况，我在matlabpool中只打开了一个worker，parfor只执行了一个循环:反正我还是有错误。当然，如果没有 parfor 块，即使多次调用 aFunction() 也不会出错。

我在命令窗口中获得的是:

Create interface with CPP handle: 139698584223104
Starting matlabpool using the 'local' profile ... connected to 1 workers.
    trying to convert handle...class_handle: trying to cast 
success in handle conversion. 

out =

    3

                  Now starting parfor ***
Save interface with CPP handle: 139698584223104
Save interface with CPP handle: 139698584223104
Create interface with CPP handle: 0
Load interface with CPP handle: 139698584223104
    trying to convert handle...class_handle: trying to cast 

------------------------------------------------------------------------
      Segmentation violation detected at Wed Jan 30 15:00:47 2013
------------------------------------------------------------------------

Configuration:
  Crash Decoding  : Disabled
  Current Visual  : None
  Default Encoding: UTF-8
  GNU C Library   : 2.15 stable
  MATLAB Root     : /usr/local/MATLAB/R2012b
  MATLAB Version  : 8.0.0.783 (R2012b)
  Operating System: Linux 3.2.0-31-generic #50-Ubuntu SMP Fri Sep 7 16:16:45 UTC 2012 x86_64
  Processor ID    : x86 Family 6 Model 42 Stepping 7, GenuineIntel
  Virtual Machine : Java 1.6.0_17-b04 with Sun Microsystems Inc. Java HotSpot(TM) 64-Bit Server VM mixed mode
  Window System   : No active display

Fault Count: 1


Abnormal termination:
Segmentation violation

Register State (from fault):
  RAX = 00007fedbcba74a0  RBX = 00007fee2afa0fe0
  RCX = 0000000000000006  RDX = 0000000000000060
  RSP = 00007fee2afa0520  RBP = 00007fee2afa09f0
  RSI = 0000000000000000  RDI = 00007fee2b817a50

  R8 = 00007fee2afa09af   R9 = 00007fedbcdb9208
  R10 = 00007fee2afa0200  R11 = 00007fee3d57ba00
  R12 = 0000000000000002  R13 = 00007f0e1c7cfd80
  R14 = 00007fee2afa0dd0  R15 = 00007fee2afa0f20

  RIP = 00007fedfc00a8e4  EFL = 0000000000010206

  CS = 0033   FS = 0000   GS = 0000

Stack Trace (from fault):
[  0] 0x00007fee3f5e31de    /usr/local/MATLAB/R2012b/bin/glnxa64/libmwfl.so+00516574 _ZN2fl4diag15stacktrace_base7captureERKNS0_14thread_contextEm+000158
[  1] 0x00007fee3f5e44b2    /usr/local/MATLAB/R2012b/bin/glnxa64/libmwfl.so+00521394
[  2] 0x00007fee3f5e5ffe    /usr/local/MATLAB/R2012b/bin/glnxa64/libmwfl.so+00528382 _ZN2fl4diag13terminate_logEPKcRKNS0_14thread_contextE+000174
[  3] 0x00007fee3e8d2093   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcr.so+00557203 _ZN2fl4diag13terminate_logEPKcPK8ucontext+000067
[  4] 0x00007fee3e8ceb9d   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcr.so+00543645
[  5] 0x00007fee3e8d0835   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcr.so+00550965
[  6] 0x00007fee3e8d0a55   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcr.so+00551509
[  7] 0x00007fee3e8d10fe   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcr.so+00553214
[  8] 0x00007fee3e8d1295   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcr.so+00553621
[  9] 0x00007fee3cdc8cb0              /lib/x86_64-linux-gnu/libpthread.so.0+00064688
[ 10] 0x00007fedfc00a8e4 /home/gwala/Documents/mexInitConfig/mex_torque_profile.mexa64+00010468 mexFunction+002116
[ 11] 0x00007fee355b269a     /usr/local/MATLAB/R2012b/bin/glnxa64/libmex.so+00112282 mexRunMexFile+000090
[ 12] 0x00007fee355ae4e9     /usr/local/MATLAB/R2012b/bin/glnxa64/libmex.so+00095465
[ 13] 0x00007fee355af33c     /usr/local/MATLAB/R2012b/bin/glnxa64/libmex.so+00099132
[ 14] 0x00007fee3e620a4b /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_dispatcher.so+00596555 _ZN8Mfh_file11dispatch_fhEiPP11mxArray_tagiS2_+000539
[ 15] 0x00007fee3deb4e56 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02264662
[ 16] 0x00007fee3de651c6 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01937862
[ 17] 0x00007fee3de69ab4 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01956532
[ 18] 0x00007fee3de660d3 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01941715
[ 19] 0x00007fee3de66ed7 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01945303
[ 20] 0x00007fee3ded2760 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02385760
[ 21] 0x00007fee3e620a4b /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_dispatcher.so+00596555 _ZN8Mfh_file11dispatch_fhEiPP11mxArray_tagiS2_+000539
[ 22] 0x00007fee35b73538  /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcos.so+01574200
[ 23] 0x00007fee35b15232  /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcos.so+01188402
[ 24] 0x00007fee35b154ce  /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcos.so+01189070
[ 25] 0x00007fee35b1723c  /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcos.so+01196604
[ 26] 0x00007fee35bfc9c7  /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcos.so+02136519
[ 27] 0x00007fee3e5d6431 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_dispatcher.so+00291889 _ZN13Mfh_MATLAB_fn11dispatch_fhEiPP11mxArray_tagiS2_+000529
[ 28] 0x00007fee3deb4933 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02263347
[ 29] 0x00007fee3dec40d8 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02326744
[ 30] 0x00007fee3dec7038 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02338872
[ 31] 0x00007fee3de6ab18 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01960728
[ 32] 0x00007fee3de660d3 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01941715
[ 33] 0x00007fee3de66ed7 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01945303
[ 34] 0x00007fee3ded2760 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02385760
[ 35] 0x00007fee3e62053b /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_dispatcher.so+00595259 _ZN8Mfh_file11dispatch_fhEP20_mdUnknown_workspaceiPP11mxArray_tagiS4_+000555
[ 36] 0x00007fee3e5e3057 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_dispatcher.so+00344151 _Z30callViamdMxarrayFunctionHandlePviPP11mxArray_tagiS2_+000039
[ 37] 0x00007fee3de3e143 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01777987
[ 38] 0x00007fee3de3f07d /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01781885
[ 39] 0x00007fee3de3f78b /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01783691
[ 40] 0x00007fee3de42759 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01795929
[ 41] 0x00007fee3de6922b /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01954347
[ 42] 0x00007fee3de660d3 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01941715
[ 43] 0x00007fee3de66ed7 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01945303
[ 44] 0x00007fee3ded2760 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02385760
[ 45] 0x00007fee3e62053b /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_dispatcher.so+00595259 _ZN8Mfh_file11dispatch_fhEP20_mdUnknown_workspaceiPP11mxArray_tagiS4_+000555
[ 46] 0x00007fee3e5e3057 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_dispatcher.so+00344151 _Z30callViamdMxarrayFunctionHandlePviPP11mxArray_tagiS2_+000039
[ 47] 0x00007fee3ddf38b5 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01472693 inFullFevalFcn+001045
[ 48] 0x00007fee3e5e66ba /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_dispatcher.so+00358074 _ZN11Mfh_builtin11dispatch_mfEiPP11mxArray_tagiS2_+000074
[ 49] 0x00007fee3e5d6431 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_dispatcher.so+00291889 _ZN13Mfh_MATLAB_fn11dispatch_fhEiPP11mxArray_tagiS2_+000529
[ 50] 0x00007fee3e0a1140 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+04280640
[ 51] 0x00007fee3e0a197a /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+04282746
[ 52] 0x00007fee3e0a24ea /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+04285674
[ 53] 0x00007fee3df054cd /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02593997
[ 54] 0x00007fee3df30d22 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02772258
[ 55] 0x00007fee3df30e4f /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02772559
[ 56] 0x00007fee3e04db30 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+03939120
[ 57] 0x00007fee3de69fec /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01957868
[ 58] 0x00007fee3de660d3 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01941715
[ 59] 0x00007fee3de66ed7 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01945303
[ 60] 0x00007fee3ded2760 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02385760
[ 61] 0x00007fee3e620a4b /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_dispatcher.so+00596555 _ZN8Mfh_file11dispatch_fhEiPP11mxArray_tagiS2_+000539
[ 62] 0x00007fee3de9388f /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02128015
[ 63] 0x00007fee3de92c69 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+02124905
[ 64] 0x00007fee3ddf129c /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01462940 inCallFcnWithTrap+000092
[ 65] 0x00007fee3de57bfb /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01883131
[ 66] 0x00007fee3ddf0168 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwm_interpreter.so+01458536 _Z28inCallFcnWithTrapInDesiredWSiPP11mxArray_tagiS1_PKcbP15inWorkSpace_tag+000104
[ 67] 0x00007fee36365b09   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwiqm.so+02878217 _ZN3iqm15BaseFEvalPlugin7executeEP15inWorkSpace_tagRN5boost10shared_ptrIN14cmddistributor17IIPCompletedEventEEE+000457
[ 68] 0x00007fedff8a992d /usr/local/MATLAB/R2012b/bin/glnxa64/libnativejmi.so+00674093 _ZN9nativejmi14JmiFEvalPlugin7executeEP15inWorkSpace_tagRN5boost10shared_ptrIN14cmddistributor17IIPCompletedEventEEE+000173
[ 69] 0x00007fedff8d6c45 /usr/local/MATLAB/R2012b/bin/glnxa64/libnativejmi.so+00859205 _ZN3mcr3mvm27McrSwappingIqmPluginAdapterIN9nativejmi14JmiFEvalPluginEE7executeEP15inWorkSpace_tagRN5boost10shared_ptrIN14cmddistributor17IIPCompletedEventEEE+000629
[ 70] 0x00007fee3633bbfa   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwiqm.so+02706426
[ 71] 0x00007fee3632d594   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwiqm.so+02647444
[ 72] 0x00007fee357d7ccd /usr/local/MATLAB/R2012b/bin/glnxa64/libmwbridge.so+00122061 _Z10ioReadLinebP8_IO_FILERKN5boost8optionalIKP15inWorkSpace_tagEEb+000429
[ 73] 0x00007fee357d8354 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwbridge.so+00123732
[ 74] 0x00007fee357dd71d /usr/local/MATLAB/R2012b/bin/glnxa64/libmwbridge.so+00145181
[ 75] 0x00007fee357dd81e /usr/local/MATLAB/R2012b/bin/glnxa64/libmwbridge.so+00145438
[ 76] 0x00007fee357ddf07 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwbridge.so+00147207 _Z8mnParserv+000631
[ 77] 0x00007fee3e8b7472   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcr.so+00447602 _ZN11mcrInstance30mnParser_on_interpreter_threadEv+000034
[ 78] 0x00007fee3e895b69   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcr.so+00310121
[ 79] 0x00007fee3e895d48   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcr.so+00310600
[ 80] 0x00007fee3eeabf73 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwservices.so+00999283 _ZN10eventqueue18UserEventQueueImpl5flushEv+000371
[ 81] 0x00007fee3eeac695 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwservices.so+01001109 _ZN10eventqueue8ReadPipeEib+000053
[ 82] 0x00007fee3eeab321 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwservices.so+00996129 _ZN10eventqueue18UserEventQueueImpl9selectFcnEb+000353
[ 83] 0x00007fee3284fa65   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwuix.so+00518757
[ 84] 0x00007fee3ef45a11 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwservices.so+01628689 _ZSt8for_eachIN9__gnu_cxx17__normal_iteratorIPN5boost8weak_ptrIN4sysq10ws_ppeHookEEESt6vectorIS6_SaIS6_EEEENS4_8during_FIS6_NS2_10shared_ptrIS5_EEEEET0_T_SH_SG_+000081
[ 85] 0x00007fee3ef46aeb /usr/local/MATLAB/R2012b/bin/glnxa64/libmwservices.so+01633003 _ZN4sysq12ppe_for_eachINS_8during_FIN5boost8weak_ptrINS_10ws_ppeHookEEENS2_10shared_ptrIS4_EEEEEET_RKS9_+000251
[ 86] 0x00007fee3ef445a2 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwservices.so+01623458 _ZN4sysq19ppePollingDuringFcnEb+000114
[ 87] 0x00007fee3ef44969 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwservices.so+01624425 _ZN4sysq11ppeMainLoopEiib+000121
[ 88] 0x00007fee3ef44b08 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwservices.so+01624840 _ZN4sysq11ppeLoopIfOKEiib+000152
[ 89] 0x00007fee3ef44c63 /usr/local/MATLAB/R2012b/bin/glnxa64/libmwservices.so+01625187 _ZN4sysq20processPendingEventsEiib+000147
[ 90] 0x00007fee3e896664   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcr.so+00312932
[ 91] 0x00007fee3e896b3c   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcr.so+00314172
[ 92] 0x00007fee3e890592   /usr/local/MATLAB/R2012b/bin/glnxa64/libmwmcr.so+00288146
[ 93] 0x00007fee3cdc0e9a              /lib/x86_64-linux-gnu/libpthread.so.0+00032410
[ 94] 0x00007fee3caedcbd                    /lib/x86_64-linux-gnu/libc.so.6+00998589 clone+000109


This error was detected while a MEX-file was running. If the MEX-file
is not an official MathWorks function, please examine its source code
for errors. Please consult the External Interfaces Guide for information
on debugging MEX-files.

If this problem is reproducible, please submit a Service Request via:
    http://www.mathworks.com/support/contact_us/

A technical support engineer might contact you with further information.

Thank you for your help.** This crash report has been saved to disk as /home/gwala/matlab_crash_dump.11705-1 **

class_handle: trying to cast 
Destroy object 0x7f0e1e45f090
class_handle: trying to cast 
Deleted myclass with handle: 139698584223104
Error using parallel_function (line 589)
The session that parfor is using has shut down.

可以看出，接口(interface)已正确创建，然后 aFunction 正确返回 'out' 的值 3(这甚至适用于多次调用)。
然后 parfor 循环开始，众所周知，matlab 对象被保存(实际上我不清楚为什么它被保存两次，但即使在命令窗口中，当我保存 myInterface 对象时也会发生这种情况)。
最后创建一个新的 myInterface，其句柄为 0，句柄恢复到正确的先前值。不过，对 aFunctions 的调用失败了。

我最后报告了 myInterface matlab 类:

classdef myInterface < handle
    properties (SetAccess = private, Transient=true)
    objectHandle; % Handle to the underlying C++ class instance
    end

    methods(Static=true)
    function obj = loadobj(this)     
        obj = myInterface();
        obj.objectHandle = this.objectHandle;
        disp(['Load interface with CPP handle: ' num2str(this.objectHandle)]);
    end
    end

    methods

    function obj = saveobj(this)
        obj.objectHandle = this.objectHandle;
        disp(['Save interface with CPP handle: ' num2str(this.objectHandle)]);
    end     


    %% Constructor - Create a new C++ class instance 
    function this = myInterface(varargin)
        if (size(varargin) == 0) % constructor with no arguments. Used in load/save operations
        this.objectHandle = 0;
        else % constructor with normal arguments
        this.objectHandle = myMexInterface('new', varargin{:});
        end
        disp(['Create interface with CPP handle: ' num2str(this.objectHandle)]);
    end

    %% Destructor - Destroy the C++ class instance
    function delete(this)
        myMexInterface('delete', this.objectHandle);
        disp(['Deleted myclass with handle: ' num2str(this.objectHandle)]);
    end

      %% aFunction
    function varargout = aFunction(this, varargin)
        [varargout{1:nargout}] =  myMexInterface('aFunction', this.objectHandle,varargin{:});
    end
    end
end

请注意，正如 [2] 中所建议的，我包含了 loadobj、saveobj 函数，并且该类具有“Transient”属性以实现加载/保存操作。

希望对某人有所帮助，我希望这篇文章可以帮助某人。

问候，
加布里埃尔·瓜兰迪

最佳答案

并行计算工具箱工作程序是独立的 MATLAB 进程——它们甚至可能运行在不同的机器上，因此它们具有独立的地址空间。如果我理解正确的话，您正在将指向在您的 MATLAB 客户端上有效的对象的指针传递给工作人员，并尝试在那里取消引用该指针。

如果您明确使用共享内存区域在客户端和工作程序之间进行通信，这可能会起作用。例如，请参阅此文件交换贡献:http://www.mathworks.co.uk/matlabcentral/fileexchange/28572-sharedmatrix .

正如我在上面提到的问题之一的解决方案中提出的替代方案是支持更完整地保存到磁盘 - 在这种情况下，这可能意味着将 C++ 对象中的内容提取到 MATLAB 结构中，并支持重新创建来自该 MATLAB 结构的 C++ 对象。

关于c++ - Matlab/C++ : segmentation fault on parallel computing with C++ Mex persistent objects (cannot convert handle)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14607109/

amp 43 MATLAB 00007 x00007 c++parallel-processing mex parfor

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