[SCIP] Help with setting up parallel solve in pyscipopt

Fri Apr 14 20:06:48 CEST 2023

 Thanks Matthias, I actually tried to do that after sending the email yesterday.

   - Built the bugfix version via cmake and installed it
   - Created a new conda environment
   - Installed pyscipopt via pip
   - SCIPOPTDIR variable is ignored.  

I'll bring this up on the github.
Thanks,Hon Fai
    On Friday, April 14, 2023 at 02:11:54 AM PDT, Miltenberger, Matthias <miltenberger at zib.de> wrote:  

 Hi Hon Fai,

Are you installing PySCIPOpt via conda or pip? I suggest using pip if you want to link your custom SCIP installation.
Did you build and install SCIP using CMake? It's important that you don't forget the install step to ensure that the directory structure is set up correctly.
It would be best if you also tried using a fresh conda environment to avoid any configuration traces from previous build/link attempts.

I hope that helps! We can also continue that discussion in a GitHub issue since this is more of a PySCIPOpt issue than a SCIP one.

Cheers,
Matthias

\__________________
Matthias Miltenberger
Zuse Institute Berlin
Takustr. 7, 14195 Berlin
www.zib.de/miltenberger

________________________________________
From: Scip <scip-bounces at zib.de> on behalf of Hon Fai Vuong <hfvuong at yahoo.com>
Sent: Friday, April 14, 2023 3:04:19 AM
To: scip at zib.de; Gleixner, Ambros
Subject: Re: [SCIP] Help with setting up parallel solve in pyscipopt

Ambrose,
    I tried again with the bugfix build, but had the same result.  Running scip on command line is fine, but calling it through pyscipopt results in a segmentation fault.  Any other ideas or things I should investigate?

I did note that the environment variable SCIPOPTDIR in my shell is being ignored.
It appears that pyscipopt is looking for scip in my /home/username/scip directory.  I don't know if that provides any type of clue.  When I move that directory pysciptopt results in an error, so I know that it's looking for scip there.

Traceback (most recent call last):
  File "scip_runner.py", line 1, in <module>
    from pyscipopt import Model
  File "/home/hv28186/.conda/envs/conda_38/lib/python3.8/site-packages/pyscipopt/__init__.py", line 11, in <module>
    from pyscipopt.scip      import Model
ImportError: libscip.so.8.0: cannot open shared object file: No such file or directory

-Thanks
Hon Fai

On Thursday, April 13, 2023 at 03:22:10 AM PDT, Ambros Gleixner <gleixner at zib.de> wrote:

Hi Hon Fai,

Great!  And yes, we have fixed some things in the concurrent mode
recently.  Can you try with the latest version of the v80-bugfix branch
on github.com/scipopt/scip ?

Best,
Ambros

Am 13.04.2023 um 01:52 schrieb Hon Fai Vuong:
> Hi Ambrose, thanks for your response.  I missed that detail and made the
> change.  I uninstalled the conda version of pyscipopt since it came with
> it's own version of scip.  I reinstalled pyscipopt via pip and it now
> appears that pyscipopt is using the version of scip that I build from
> src. It runs normally with the optimize() function.
>
> However when I try with the concurrentopt, it segfaults and produces a
> core file.  I'm not sure what to do next.
>
> -Hon Fai
>
> On Wednesday, April 12, 2023 at 05:39:55 AM PDT, Ambros Gleixner
> <gleixner at zib.de<mailto:gleixner at zib.de>> wrote:
>
>
> Hi Hon Fai,
>
> Did you see the description at
>
> https://github.com/scipopt/PySCIPOpt/blob/master/INSTALL.md
> <https://github.com/scipopt/PySCIPOpt/blob/master/INSTALL.md>
>
> ?  You may have to set `export SCIPOPTDIR=<path_to_install_dir>` in your
> shell.
>
> Best,
> Ambros
>
> Am 11.04.2023 um 21:08 schrieb Hon Fai Vuong:
>  > Hello All,
>  >      I'm new to SCIP and wanted to try running with concurrent opt
>  > mode.  I'm working on Linux and was able to install the scip package via
>  > cond-forge, but when I attempted to use the parallel functionality via
>  > solveConcurrent(),
>  >
>  > I received the following warning:
>  >
>  > *UserWarning('SCIP was compiled without task processing interface.
>  > Parallel solve not possible - using optimize() instead of
>  > solveConcurrent()')*
>  >
>  > I read that by default SCIP isn't compiled with the TPI option, so went
>  > through the process of building it after much fumbling around.
>  > I can solve problems via command line with parallel mode with the
>  > rebuilt version.
>  >
>  > My question now is how to I tell psyscipopt to use that version?  I
>  > naively created a symlink to point the version of scipt in my virtual
>  > environment to the rebuilt version, but still running into the same
> problem.
>  >
>  > Any help would be appreciated.
>  >
>  > Thanks,
>  > Hon Fai
>
>  >
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