[CP2K-user] [CP2K:11009] ASE CP2K interface

[Ole Schütt]

Hi Geng,

this sounds indeed like a buffering issue. Could you once try to add a 
flush() on the python side.

Basically add the following line after cp2k.py:498.

         self._child.stdin.write(line + '\n')
+       self._child.stdin.flush()

This is probably quite inefficient. So, if it works I'll add some logic 
to flush only when recv() follows a send().


-Ole


On 2018-12-04 18:08, Geng Sun wrote:
> Dear CP2K users,
> 
>  In the past several weeks, I frequently faced a problem when I use
> the CP2K -ASE interface.
> 
>  The calculations frequently got stuck during the calculations.
> 
> 1) Firstly I switched on the debug=True option in the ASE-CP2K
> calculator and I found that the calculation always gets stuck at a
> line with *END after sending the positions to the subroutine
> cp2k_shell.popt  (I printed the information to the standard error, so
> they are not buffered)
> 
> 2) Then, I modified the cp2k_shell.F to print a lot of "labels". Then
> I found that the code may get stuck at the line of "READ
> (*,*,iostat=iostat) pos" like below. I can always get "begin to read
> pos" in the standard error, but I can not reach "LABEL-1".
> 
>            WRITE(0,*) "begin to read pos"
>            CALL m_flush(0)
>            READ (*,*,iostat=iostat) pos
>            WRITE(0,*) "LABEL-1"
>            CALL m_flush(0)
> 
> I attached the modified cp2k_shell.F and the standard out/error
> generated by the slurm batch system with this post. You can see that
> the program get stuck at the second optimization step just after
> sending the positions.
> 
> I greatly appreciate your suggestions for fixing this confusing bugs.
> 
> Thanks in advance.
> 
> Geng
> 
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