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0004285

VTK

(No Category)

public

2007-01-08 04:11

2012-03-07 03:16

Reporter

xabi riobe

Assigned To

Lisa Avila

Priority

normal

Severity

major

Reproducibility

always

Status

closed

Resolution

fixed

Platform

OS Version

Product Version

Target Version

Fixed in Version

Summary

0004285: thread event leads to deadlock

Description

The problem comes from the following macro in vtkFixedPointVolumeRayCastHelper.h :

//BTX
#define VTKKWRCHelper_IncrementAndLoopEnd() \
      imagePtr+=4; \
      } \
    if( 0==threadID && ( j%10 || j==imageInUseSize[1]-1 ) ) /*if ( j%32 == 31 )*/ \
      { \
      double fargs[1]; \
      fargs[0] = static_cast<double>(j)/static_cast<float>(imageInUseSize[1]-1); \
      mapper->InvokeEvent( vtkCommand::VolumeMapperRenderProgressEvent, fargs ); \
      } \
    }
//ETX

I have a vtkCommand observing the event that calls a method
SetProgressState(value) of an object containing a wxProgressDialog
that will be updated with the value comming from 'fargs'.

The problem is that wxProgressDialog calls a "SendMessage" (windows)
and if the event has been fired in a thread that is not the main one,
all that leads to a deadlock when trying to draw the progress bar.

For example if we have two threads for the raycast, the main one will
be in charge of the pair values for the j variable and the event will
be fired by the other thread (when j%32 == 31, j is not pair)

So a solution to avoid that is replacing the "if" line in the #define
by this one:

if( 0==threadID && ( j%10 || j==imageInUseSize[1]-1 ) )

In that case the event is only fired by the main thread.
( j%10 is to have a more precise progression and
j==imageInUseSize[1]-1 is to have the value 1.0 with the ProgressEvent
and not only for the EndProgressEvent ).

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Notes
(0006105) xabi riobe (reporter) 2007-01-08 04:19	oops, the macro posted is after the patch, the original one is with the code commented: if ( j%32 == 31 )

(0007041) xabi riobe (reporter) 2007-04-02 10:12	sorry, the j%10 must be replaced by (j%10 == 0) of course (or another value instead of 10, just an example).

Issue History
Date Modified	Username	Field	Change
2011-06-16 13:11	Zack Galbreath	Category	=> (No Category)
2012-03-07 03:16	xabi riobe	Status	expired => closed
2012-03-07 03:16	xabi riobe	Resolution	open => fixed