[gdal-dev] No IDATs written into file

[Even Rouault]

Le samedi 14 novembre 2015 17:46:47, Ari Jolma a écrit :
> I'm using the Translate function to clip tiles from a larger raster
> using Perl bindings. I'm clipping into PNG files.
> 
> This is in a web service environment, i.e., several workers listening to
> a client.

Ari,

Are the workers multi-threaded or each in their own process ?

But even in the multi-threaded case, I can't reproduce with the following :

#include "cpl_multiproc.h"
#include "gdal_utils.h"
#include "gdal.h"

void copyFunc(void* arg)
{
    const char* pszOut = (const char*)arg;
    GDALDatasetH hSrcDS = GDALOpen("byte.tif", GA_ReadOnly);
    char* argv[] = { "-of", "PNG", NULL };
    GDALTranslateOptions* psOptions = GDALTranslateOptionsNew(argv, NULL);
    GDALClose(GDALTranslate(pszOut, hSrcDS, psOptions, NULL));
    GDALClose(hSrcDS);
    GDALTranslateOptionsFree(psOptions);
}

int main(int argc, char* argv[])
{
    CPLJoinableThread *ht1, *ht2;
    GDALAllRegister();
    while(1)
    {
        ht1 = CPLCreateJoinableThread(copyFunc, "test1.png");
        ht2 = CPLCreateJoinableThread(copyFunc, "test2.png");
        CPLJoinThread(ht1);
        CPLJoinThread(ht2);
    }
}

I assume your GDAL is built --with-threads (which is the default) if you use 
it in a multi-threaded context.

Even

> The Translate fails in pngwrite.c, in png_write_end with error
> "No IDATs written into file".
> 
> The script works fine when I have only one worker.
> 
> I have tried writing the file into file system, VSI file system, etc.
> The error is the same. The output seems to be consistently 33 bytes
> long, i.e., only the header I guess.
> 
> I'm using unique file names.
> 
> Any ideas?
> 
> Ari
> 
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