Batch Processor can appear to be frozen

[Tveloso]

I have a Batch Processor preset that I use occasionally to put files on my wife's PC, and strip them of all Metadata (so she can then post them to websites where she purchases prints/PhotoBooks), and I noticed that when the Batch Processor reaches what appears very near the end of its processing (the time estimate says "less than 15 seconds", and the file referenced is only a few away from the last one), that dialog stays up for quite a long while, before the process eventually completes successfully.

I initially thought that the Batch Processor might be locked up, but I later learned that at that stage of the processing (when that "15 seconds remaining" message is up for an extended period of time),  IMatch is actually running ExifTool on all the newly created files in the target directory (I could see the "_original" file being created, and then deleted, in turn for each file), and that processing takes some time...(I imagine particularly because the files are being written out to another PC, over a network connection).

I figured that this "additional ExifTool work" was because I had requested to have all Metadata stripped, but wondered why IMatch did not do this as part of writing out each individual target file, and deferred it to the very end, after all files had been created. I think (and here I may be mistaken) that I later determined that in fact IMatch does strip the Metadata from each file as it's written, and this at-the-end ExifTool work is "a second pass" for some reason.

Having that dialog box, with the message that there are only about 15 seconds left, staying up for a long period of time, might lead some users to think IMatch has frozen.

When I have a chance, I'll recreate this, and will provide a debug log, and more details on my Batch Processor Preset.

[Mario]

why IMatch did not do this as part of writing out each individual target file, and deferred it to the very end,

The image libraries used to produce the output files add metadata to files when they support metadata. Like IFD0 or EXIF.
If you tell the batch processor to wipe everything, IMatch does that in one call to ExifTool at the end. This is much faster than doing it for each file, every time launching a new ExifTool process etc.
But since IMatch at this time has to "wait" for ExifTool to finish, the progress bar does not move during that time. It's "one" operation of many, after all.

Your use case is of course somewhat special. Processing hundred of file to a very slow output medium and requesting to delete all metadata too...

Not sure if this is something I should add some additional UI or progress feedback for. As far as I can recall, this was never reported as an issue before and I wonder how many users are affected by this.

I shall look into this when there is a free time slot.