pymapdl

pymapdl copied to clipboard

Before submitting the issue

• [X] I have searched among the existing issues
• [ ] I am using a Python virtual environment
• [x] I have a fully updated virtual environment (i.e. pip install --upgrade --upgrade-strategy eager ansys-mapdl-core)

Description of the bug

I am running pyAnsys from julia with PyCall, with an ansys student license (2022 R2).

I noticed that when there are several interactions with mapdl the connection might break because APDL crashes and I get the error attached below. The number of mapdl.some_command before the connection is lost looks to be completely random, sometimes it is in the order of 10, some times in the order of 100/200. The workaround I found is to use a try catch statement which in case of a lost connection will start new mapdl server connection and restore the model from a saved file. It is working, but I'm sure it's not the best solution. The flowchart of the try catch is:

mapdl.run("save,fileName''db',path")
try
  mapdl.run_multiline("""
    some APDL commands
    """)
catch
  mapdl = pymapdl.launch_mapdl(additional_switches="-smp",mode="grpc")
  mapdl.run("resume,filename,'db',path")
  mapd.run_multiline("""
    some APDL commands as above
    """)
end

Some notes:

1. I am not using a python virtual environment b/c (i) I am working in julia so I don't know if it is necessary and (ii) it looks to be an APDL problem since it is the one that keeps crashing.
2. I almost only use mapdl.run("an APDL command"), mapdl.run_multiline("""some APDL commands"""), mapdl.get("datum from database), could it be an issue? In the #544, which was related to *DO loops instability, it was suggested to use the python equivalent for loop. Would it be better to convert all the mapdl.run_multiline() in the pyansys equivalent commands?
3. the try catch workaround is terrible to look at. I could do something better with a while loop, but it still would be a palliative and not a solution to APDL crashing for no apparent reasons

Thankyou all, I hope I haven't written atrocities, I am more of an APDL user than a julia/python user

Steps To Reproduce

Steps:

• launch MAPDL using PyCall with -smp and mode = "grpc":

using PyCall
pymapdl = pyimport("ansys.mapdl.core")
mapdl = pymapdl.launch_mapdl(additional_switches="-smp",mode="grpc")

• run lots of mapdl.run_multiline("some APDL commands")
• run lots of mapdl.get("some database data")

Which Operating System are you using?

Windows

Which Python version are you using?

3.10

PyMAPDL Report

PyError ($(Expr(:escape, :(ccall(#= C:\Users\Francesco\.julia\packages\PyCall\ygXW2\src\pyfncall.jl:43 =# @pysym(:PyObject_Call), PyPtr, (PyPtr, PyPtr, PyPtr), o, pyargsptr, kw))))) <class 'ansys.mapdl.core.errors.MapdlExitedError'>
MapdlExitedError('MAPDL server connection terminated')
  File "C:\Users\Francesco\.julia\conda\3\lib\site-packages\ansys\mapdl\core\mapdl.py", line 2540, in run_multiline
    return self.input_strings(commands=commands)
  File "C:\Users\Francesco\.julia\conda\3\lib\site-packages\ansys\mapdl\core\mapdl.py", line 2593, in input_strings
    self._flush_stored()
  File "C:\Users\Francesco\.julia\conda\3\lib\site-packages\ansys\mapdl\core\mapdl_grpc.py", line 1531, in _flush_stored
    out = self.input(
  File "C:\Users\Francesco\.julia\conda\3\lib\site-packages\ansys\mapdl\core\errors.py", line 145, in wrapper
    raise MapdlExitedError("MAPDL server connection terminated") from None

Stacktrace:
  [1] pyerr_check
    @ C:\Users\Francesco\.julia\packages\PyCall\ygXW2\src\exception.jl:62 [inlined]
  [2] pyerr_check
    @ C:\Users\Francesco\.julia\packages\PyCall\ygXW2\src\exception.jl:66 [inlined]
  [3] _handle_error(msg::String)
    @ PyCall C:\Users\Francesco\.julia\packages\PyCall\ygXW2\src\exception.jl:83
  [4] macro expansion
    @ C:\Users\Francesco\.julia\packages\PyCall\ygXW2\src\exception.jl:97 [inlined]
  [5] #107
    @ C:\Users\Francesco\.julia\packages\PyCall\ygXW2\src\pyfncall.jl:43 [inlined]
  [6] disable_sigint
    @ .\c.jl:473 [inlined]
  [7] __pycall!
    @ C:\Users\Francesco\.julia\packages\PyCall\ygXW2\src\pyfncall.jl:42 [inlined]
  [8] _pycall!(ret::PyObject, o::PyObject, args::Tuple{String}, nargs::Int64, kw::Ptr{Nothing})
    @ PyCall C:\Users\Francesco\.julia\packages\PyCall\ygXW2\src\pyfncall.jl:29
  [9] _pycall!(ret::PyObject, o::PyObject, args::Tuple{String}, kwargs::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})       
    @ PyCall C:\Users\Francesco\.julia\packages\PyCall\ygXW2\src\pyfncall.jl:11
 [10] (::PyObject)(::String, ::Vararg{Any}; kwargs::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ PyCall C:\Users\Francesco\.julia\packages\PyCall\ygXW2\src\pyfncall.jl:86
 [11] (::PyObject)(::String, ::Vararg{Any})
    @ PyCall C:\Users\Francesco\.julia\packages\PyCall\ygXW2\src\pyfncall.jl:86
 [12] the function where I use mapdl.some_command

Installed packages

This is what I get with

using PyCall
py"""
       help('modules')
       """

</details>

Oct 24 '22 14:10 francesco123212

Hi @francesco123212 Sorry, I accidentally hit send on the comment before I was ready...and with a half-baked idea. Can you post some APDL that results in the server disconnection? Mike

Oct 24 '22 14:10 mikerife

Hi @francesco123212 Sorry, I accidentally hit send on the comment before I was ready...and with a half-baked idea. Can you post some APDL that results in the server disconnection? Mike

here it is @mikerife. I use it for the prediction of the driving force in terms of SIF of a crack in notched plate, so it goes in a loop that changes the length of the crack and its height wrt the symmetry plane. (I have tested the codes on my PC and they are working):

#useless for python users
using PyCall
pymapdl = pyimport("ansys.mapdl.core")

mapdl = pymapdl.launch_mapdl(additional_switches="-smp",mode="grpc")
mapdl.run_multiline("""
  /clear
  !
  *set,toll,1e-5
  *set,pi,2*asin(1)
  !-----------------------------------------------------!
  !       SCHEMATIC ILLUSTRATION OF THE SPECIMEN        !
  !-----------------------------------------------------!
  !     /) alpha
  !    /_________________________________
  !   /         |
  !  /          |
  ! |    |      | hh2 = 7.50
  ! |    | hh1  |
  ! |____|______|________________________
  ! 
  ! <----------------LL = 40------------>
  !-----------------------------------------------------!
  !                  GEOMETRY PARAMETERS                !
  !-----------------------------------------------------!
  ! geometry
  *set,rho,0.1
  *set,hh1,2.52
  *set,hh2,7.50
  *set,LL,40
  *set,aa_notch,hh2-hh1
  *set,alpha2,90 !deg
  /prep7
  !-----------------------------------------------------!
  !   ELEMENT TYPE AND MATERIAL PROPERTIES DEFINITION   !
  !-----------------------------------------------------!
  et,1,182		!Plane 4
  keyopt,1,1,3	!Simple Enhanced strain formulation
  keyopt,1,3,2	!Plane strain
  ! mp definition
  mp,Ex,1,114e3
  mp,PRxy,1,.34
  !-----------------------------------------------------!
  !         NOMINAL GEOMETRY WO CRACKS/DEFECTS          !
  !-----------------------------------------------------!
  k,10000,-(hh1+rho)
  circle,10000,rho,,,alpha2/2
  kDele,10000
  kSel,u,loc,y,-toll,toll
  *get,tmp1,kp,kpNext(0),loc,x
  *set,tmp1,hh2+tmp1
  *get,tmp2,kp,kpNext(0),loc,y
  allSel
  k,,-hh2,tmp2+tmp1
  k,,-hh2,LL
  k,,,LL
  k
  *del,tmp1
  *del,tmp2
  !
  *get,n_kp,kp,0,count
  *do,i,2,n_kp-1
  l,i,i+1
  *endDo
  lSymm,y,all
  numMrg,kp,toll,,,low
  !merge lines
  kSel,s,loc,y,-toll,toll
  kSel,u,loc,x,-toll,toll
  lSlK,s
  lComb,all,,0
  ! now reselect all
  allSel
  aL,all             
   """)
cSys_crackTip = 11
crackLength = 0.007 #mm
cv_count = 8
elmSizes = [0.0014; 0.0028; 0.0056; 0.0112; 0.0224; 0.0448; 0.0896; 0.1792; 0.3584]
cvSizes = [0.014; 0.0252; 0.0420; 0.0756; 0.1428; 0.2772; 0.5460; 1.0836]
crackHeight = 0
crackOrientation = 0
elmAlongCrack_count = 5
# create the local reference system at crack tip
mapdl.run_multiline("""
  ksel,none
  lsel,s,loc,x,-hh2-toll,-hh1+toll
  wpoffs,,$crackHeight
  wprota,,90
  lsbw,all
  wpcsys,-1,0
  *set,x_crackTip,kx(kpnext(0))
  *set,y_crackTip,ky(kpnext(0))
  allsel
  ! now move WP at the desired location
  wpOffs,x_crackTip,y_crackTip
  wpRota,$crackOrientation
  wpOffs,$crackLength
  ! create the local reference system
  cSWpla,$cSys_crackTip
  ! move all back to the origin
  csys,0
  """)
# create cracks
crackMaker_2D(cSys_crackTip,crackLength,elmAlongCrack_count,cv_count,cvSizes)
cVMesher_2D(cv_count,elmSizes)
#=
apply BCs and solve
=#
mapdl.run_multiline("""
  lSel,s,loc,y,LL-toll,LL+toll
  sfL,all,pres,-1
  lSel,s,loc,y,-LL-toll,-LL+toll
  dL,all,0,uy
  lSel,s,loc,x,-toll,toll
  dL,all,0,symm
  allSel
  /solu
  eqSlv,pCG
  solve
  /post1
  """)
#=
PSM application on the node edge:
step0: create the named selection for the crack tip node
step1: apply PSM and compute for SFIs/N-SIFs at the crack tip/notch tip node
=#
# step0
mapdl.run_multiline("""
  ! switch to local reference system W origin at crack tip
  cSys,$cSys_crackTip
  ! select crack tip node
  kSel,s,loc,y,-toll,toll
  kSel,r,loc,x,-toll,toll
  ! switch back to 
  cSys,0
  cm,Vnotch_tip,kp
  allsel
  """)
# step 1 (for now a simplified version, only BC I already know the stress at the notch tip!)
mapdl.run_multiline("""
  ! select the kp of interet (I already know it is one!)
  cmSel,s,Vnotch_tip,kp
  ! select attached kp
  nSlK,s
  ! get ID of the node
  """)
nd_ID = int(mapdl.get("tmp","NODE",0,"NXTH"))
sy = mapdl.get("tmp","NODE",nd_ID,"S","Y")

where:

    function cvMaker_2D(cSys_crackTip::Int,cvSize::Number)
  mapdl.run_multiline("""
    cSys,$cSys_crackTip
    wpCSys,-1,$cSys_crackTip
    ! unselect all lines, areas and kps 
    asel,none
    lsel,none
    ksel,none
    ! create the square control volume
    rectng,$cvSize,-$cvSize,$cvSize,-$cvSize
    ! remove the newly created area only
    adele,all
    ! select the area to be divided by the cv lines and divide
    cmSel,all
    asel,inve
    asbl,all,all
    """)
end
function crackMaker_2D(cSys_crackTip::Int,crackLength::Number,elmAlongCrack_count::Number,cv_count::Int,cvSizes::AbstractArray)
  #=
  create the first control volume and the crack
  =#
  mapdl.run_multiline("""
    ! switch to the cSys  cSys_crackTip
    cSys,$cSys_crackTip
    wpCSys,-1,$cSys_crackTip
    ! unselect all lines and areas
    lsel,none
    asel,none
    ! create the square control volume
    rectng,$(crackLength/elmAlongCrack_count),-$(crackLength/elmAlongCrack_count),$(crackLength/elmAlongCrack_count),-$(crackLength/elmAlongCrack_count)
    rectng,$(cvSizes[1]),-$(cvSizes[1]),$(cvSizes[1]),-$(cvSizes[1])
    ! delete newly created areas only (not lines and below)
    adele,all
    asel,all
    ! divide the area by the newly created rectangles lines
    ! to obtain the first CV
    asbl,all,all
    ! select the newly created CVs (2!)
    asel,s,loc,y,-$(cvSizes[1])-toll,$(cvSizes[1])+toll
    asel,r,loc,x,-$(cvSizes[1])-toll,$(cvSizes[1])+toll
    ! divide the CVs to obtain the crack
    wprota,,-90
    asbw,all
    ! geometry manipulations to have redundant edges on the 
    ! crack
    wprota,-90,90
    lsel,s,loc,y
    lsel,r,loc,z,-$(cvSizes[1])+toll,$crackLength
    lsbw,all
    !
    asel,r,loc,y,0,$(cvSizes[1])
    agen,2,all,,,,,10,,1
    asel,r,loc,z,-$(cvSizes[1]),$(cvSizes[1])
    adele,all
    asel,s,loc,y,0-toll,$(cvSizes[1])+toll
    asel,r,loc,z,10-toll,10+toll
    agen,1,all,,,,,-10,,1,1
    wprota,180,,90
    wprota,,180
    !              
    ksel,s,loc,y,-toll,toll
    ksel,r,loc,x,-$crackLength-toll,-toll
    ksel,inve
    numMrg,kp
    asel,s,loc,y,-$(cvSizes[1])-toll,$(cvSizes[1])+toll
    asel,r,loc,x,-$(cvSizes[1])-toll,$(cvSizes[1])+toll
    ! create a named selection for the cracked areas
    cm,cracked_ar,area
    ! go back to the global cSys
    cSys,0
    ! remove unnecessary lines
    allsel
    lsla,u
    ldele,all,1
    !
    allsel
    """)
  #=
  create further CVs
  Here a try catch error could be implemented, printing a warning when error
  =#
  for i in 2:cv_count
    cv_ID = i
    cvSize = cvSizes[i]
     #=
    create the control volume selection
    =#
    cvMaker_2D(cSys_crackTip,cvSize)
    #=
    create the named selection
    =#
    mapdl.run_multiline("""
      asel,none
      cmSel,all
      asel,inve
      asel,r,loc,y,-$cvSize-toll,$cvSize+toll
      asel,r,loc,x,-$cvSize-toll,$cvSize+toll
      cm,cv%$cv_ID%_ar,area
      """)
  end
  mapdl.run_multiline("""
    allSel
    csys,0
    """)
end

function cVMesher_2D(cv_count::Number,elmSizes::AbstractArray)
  #=
  start meshing the cracked areas (cv0)
  =#
  mapdl.run_multiline("""
    cmSel,s,cracked_ar,area
    esize,$(elmSizes[1])
    amesh,all
    """)
  #=
  mesh the control volumes now
  =#
  for i in 2:cv_count
  cv_ID = i
  elmSize = elmSizes[i]
  mapdl.run_multiline("""
    cmSel,s,cv%$cv_ID%_ar,area
    esize,$elmSize
    amesh,all
    allsel
    """)
  end
  #=
  the rest of the volume
  =#
  mapdl.run_multiline("""
    allsel
    !unselect already meshed araes
    asel,u,type,,-1
    esize,$(elmSizes[end])
    amesh,all
    allsel""")
end
int(x) = floor(Int,x)

Oct 24 '22 15:10 francesco123212

I reiterate that the connnection, to my eyes, is lost completely randomly. Sometimes at the 2nd simulation, sometimes at the 20th its a bit annoying

Oct 24 '22 15:10 francesco123212

@FredAns, I think this server connection instability is going to keep coming up until we fix how we're writing output to disk.

@francesco123212, whenever possible, either call commands with mute=True as in mapdl.prep7(mute=True), or enable mute globally with mapdl.mute = True as there's a known instability when outputting from MAPDL to a temporary file to get the output.

Oct 25 '22 20:10 akaszynski

@akaszynski, thanks for the advice. I tried to go with mapdl.mute = true, but it still crashes sometimes. To avoid the fatal error in my code I am doing smt like:

mapdl.run("save,fileName''db',path")
while true
  try
    mapdl.run_multiline("""
      some APDL commands
      """)
      break
  catch
    mapdl = pymapdl.launch_mapdl(additional_switches="-smp",mode="grpc")
    mapdl.mute = true
    mapdl.run("resume,fileName''db',path")
    continue
  end
end

Oct 26 '22 10:10 francesco123212

@akaszynski, thanks for the advice. I tried to go with mapdl.mute = true, but it still crashes sometimes. To avoid the fatal error in my code I am doing smt like:

mapdl.run("save,fileName''db',path")
while true
  try
    mapdl.run_multiline("""
      some APDL commands
      """)
      break
  catch
    mapdl = pymapdl.launch_mapdl(additional_switches="-smp",mode="grpc")
    mapdl.mute = true
    mapdl.run("resume,fileName''db',path")
    continue
  end
end

@francesco123212 does this works?

Oct 28 '22 07:10 germa89

Hi @germa89,

adding mapd.mute = true does not solve the connection to MAPDL issue. With the while true loop and try catch statement it works fine, but it's slow and I don't like the solution

Oct 28 '22 07:10 francesco123212

Personally I dont like the solution either. But if it is a server side issue, it will take a while to be solved.

Oct 28 '22 08:10 germa89

Could it be related to my student license?

Oct 28 '22 08:10 francesco123212

Honestly I don't think so/I hope not!

Oct 28 '22 08:10 germa89

dear @germa89, is it possible that if the code runs into several errors in APDL, then APDL crashes resulting in the loss of the connection?

Feb 03 '23 09:02 francesco123212

it is very likely that. You should check any error file in the mapdl.directory.

Feb 20 '23 10:02 germa89