Call engOpen in C code, launch functionnal matlab engine but hangs on C process

2021 12 8
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更新时间：2024 5 1
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0 个投票

Hello, I'm testing matlab engine library with engdemo.c exemple.
Compiling the code directly with gcc:
$ export LD_LIBRARY_PATH="matlabroot/bin/glnxa64"
$ mv matlabroot/sys/os/glnxa64/libstdc++.so.6 matlabroot/sys/os/glnxa64/libstdc++.so.6.old (get rid of the clunky matlabroot/sys/os/glnxa64/libstdc++.so.6 in a dirty way and use /usr/lib/x86_64-linux-gnu/libstdc++.so.6 instead)
$ gcc -o engdemo -L matlabroot/bin/glnxa64 -lmx -leng -lm -lmex -lmat engdemo.c -Imatlabroot/extern/include
But when I run the executable, it calls engOpen(), launch a matlab command window but then hang inside the function. If I manually quit the matlab command window engOpen release the process but return NULL.
Thanks for your help!
EDIT: explicit "get rid of the clunky matlabroot/sys/os/glnxa64/libstdc++.so.6 in a dirty way and use /usr/lib/x86_64-linux-gnu/libstdc++.so.6 instead" sentence with the command used.

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Yongjian Feng
Yongjian Feng 2021-12-8
Not sure what you meant by "(get rid of the clunky matlabroot/sys/os/glnxa64/libstdc++.so.6 in a dirty way and use /usr/lib/x86_64-linux-gnu/libstdc++.so.6 instead)", and why you need that. Does it work if you don't do that?
Nathan Arbeid
Nathan Arbeid 2021-12-8
I rename libstdc++.so.6 to libstdc++.so.6.old.
If I don't, here is the link error I get:
```
/usr/bin/ld: /opt/Matlab/R2020b/bin/glnxa64/../../sys/os/glnxa64/libstdc++.so.6: __cxa_thread_atexit_impl: invalid needed version 48
/usr/bin/ld: /opt/Matlab/R2020b/bin/glnxa64/../../sys/os/glnxa64/libstdc++.so.6: error adding symbols: bad value
collect2: error: ld returned 1 exit status
```
And when I said that the linker use /usr/lib/x86_64-linux-gnu/libstdc++.so.6, it is speculation, I did not verify.
Yongjian Feng
Yongjian Feng 2021-12-9
Again, not a good idea. You renamed the libstdc++ shipped with matlab to force the process to use the system libstdc++. This will force matlab to use that lib as well. It can cause trouble.
Nathan Arbeid
Nathan Arbeid 2021-12-14
Ok do you have suggestions to resolve this issue in a cleaner way ?

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 采纳的回答

Nathan Arbeid
Nathan Arbeid 2021-12-9

0 个投票

My hang issue was resoleved by setting the environement variable $PATH
export PATH=matlabroot/bin:$PATH
as suggested here https://fr.mathworks.com/help/matlab/matlab_external/run-linux-engine-application.html
But do not understand why.

更多回答（1 个）

Douglas
Douglas 2024-5-1

0 个投票

I had a similar problem on MatLab R2024a running on Fedora 40, linux kernel 6.8.7. My c program would stuck on engOpen() call and would not recover.
I could find the solution using
strace -f ./myprogram
This showed that to use MatLab Engine you need to install the csh package. On fedora it's simple as:
sudo dnf install tcsh
I find the documentation should have this package as a dependency since not all linux comes with csh preinstalled.

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