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May 2011
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2011.05.06 17:07 "Re: Is LibTiff 3.9.5 Thread Safe ?", by Katerina Sedivy
You are right Bob, Delphi isn't thread safe either without a certain flag
which I already have furthermore because I am using Delphi 6 I had even
changed the memory manager since it is not thread safe as well.
However in file tif_dir.c I found this comment:
"* This can happen if multiple images are open with different
* codecs which have private tags. The global tag information
* table may then have tags that are valid for one file but not
* the other. If the client tries to set a tag that is not valid
* for the image's codec then we'll arrive here. This
* happens, for example, when tiffcp is used to convert between
* compression schemes and codec-specific tags are blindly copied."
I found this comment in the function _TIFFVGetField in the default section
of the switch for the tags. The same comment exists in the SetField
function.
Katerina
On Thu, May 5, 2011 at 4:16 PM, Bob Friesenhahn <
bfriesen@simple.dallas.tx.us> wrote:
> On Thu, 5 May 2011, Katerina Sedivy wrote:
>
> <<a bunch of threads requested to open different TIFF files all at the
>> same time>>
>> This is exactly my case
>>
>> <<the library has been exercised at least once>>
>> What do you mean by exercised?
>>
>
> For example, reading or writing a file.
>
> There is no specific thread-safety code in libtiff. The code is written to
> be re-entrant but there are still some static variables.
>
> On some systems, it is necessary to build code with particular options in
> order to be thread safe (e.g. C library functions may otherwise not be
> thread safe). Libtiff does not (by itself) provide any such build options.
>
>
> Bob
> --
> Bob Friesenhahn
> bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
> GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
>