# 2 processes read 3 files into vtkMultiBlockDataSet cannot display correctly in server-client mode

**URL:** https://discourse.paraview.org/t/2-processes-read-3-files-into-vtkmultiblockdataset-cannot-display-correctly-in-server-client-mode/1967
**Category:** Development
**Created:** [May 30, 2019, 12:17pm UTC](https://discourse.paraview.org/t/2-processes-read-3-files-into-vtkmultiblockdataset-cannot-display-correctly-in-server-client-mode/1967 "2019-05-30T12:17:11Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![sharon](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/s/67e7ee/32.png) [@sharon](https://discourse.paraview.org/u/sharon)
#### Post date: [May 30, 2019, 12:17pm UTC](https://discourse.paraview.org/t/2-processes-read-3-files-into-vtkmultiblockdataset-cannot-display-correctly-in-server-client-mode/1967/1 "2019-05-30T12:17:11Z")

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Dear Experts,  
I distribute 3 files to 2 process to generate 3 vtkMultiBlockDataSet, but paraview UI cannot display successfully…  
I tried two situations:  
\<1\> Situation 1

> Set numberOfBlock=3 for both process\_0 and process\_1  
> process\_0 read file\_0 and file\_1 and generate block\_0 and block\_1  
> process\_1 read file\_2 and generate block\_2

In this situation, i cannot see block\_2 on the render window, only multiBlockInspector can display 3 blocks, but when click block\_2, there is nothing happened…

\<2\> Situation 2

> process\_0 read file\_0 and file\_1 and generate block\_0 and block\_1  
> process\_1 read file\_2 and generate block\_0 (\*\*\* here set block number = 0, different with \<1\> \*\*\*)

In this situation, i can see there are 3 blocks in render window, BUT multiBlockInspector only display block\_0 and block\_1, when toggle block\_0, seems it controls both block\_0 and block\_2  
Paraview also pop up below error message:  
ERROR: In paraview\VTK\Common\DataModel\vtkDataObjectTree.cxx, line 377  
vtkMultiBlockDataSet (000001D72A9B4E20): Structure does not match. You must use CopyStructure before calling this method.

I am confused about this result…  
How to implement parallel read correctly when using vtkMultiBlockDataSet?  
Could you please help me out!

Thanks and Best Regards,  
Sharon

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### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [June 3, 2019, 12:42pm UTC](https://discourse.paraview.org/t/2-processes-read-3-files-into-vtkmultiblockdataset-cannot-display-correctly-in-server-client-mode/1967/2 "2019-06-03T12:42:42Z")

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There is clearly a problem in the block structures, but we do not have enough information to help you here.

I would suggest trying to show us what structure you want to achieve first, then compare it to the code you use to create the structure.

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### Author: ![sharon](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/s/67e7ee/32.png) [@sharon](https://discourse.paraview.org/u/sharon)
#### Post date: [June 4, 2019, 11:42pm UTC](https://discourse.paraview.org/t/2-processes-read-3-files-into-vtkmultiblockdataset-cannot-display-correctly-in-server-client-mode/1967/3 "2019-06-04T23:42:07Z")

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Hi Mathieu,  
Thank you for your reply!

After some tries, i found the problem:  
in parallel mode, it is require to have the same profile for vtkMultiBlockDataSet for all the CPUs, or else there will be display issues.  
I fixed this issues by adding the same number of block for all the CPUs, then let the CPU know which block it should deal with, which block it just ignore.

Best Regards,  
Sharon