ExifTool Forum

ExifTool => Bug Reports / Feature Requests => Topic started by: dlgkjfgkwrj on August 04, 2022, 02:50:30 PM

Title: Is there a reason that -listw would be much slower than -list?
Post by: dlgkjfgkwrj on August 04, 2022, 02:50:30 PM
I'm using ExifTool version 12.42 on Windows 10.

In my app, I open ExifTool in `-stay_open` mode. If the version of ExifTool has changed, I regenerate a list of supported groups and tags, both readable and writable.

So I get the groups and then for each group execute

-list -GROUPNAME:all -tab

or

-listw -GROUPNAME:all -tab

There are quite a few group names so if it doesn't run fast, it can take a couple minutes.

My question is with regard to `-list` vs `-listw`. When I run the `-list` version, I can query 5+ tags per second. When I run the `-listw` I can only query about 1 tag every 2 seconds.

Is there a reason for this speed difference between the two versions? Is it expected?
Title: Re: Is there a reason that -listw would be much slower than -list?
Post by: Phil Harvey on August 04, 2022, 05:52:28 PM
The -listw option does do a bit more work because the write modules also have to be loaded, but here I don't see a significant time difference between the two:

> time exiftool -list > t1
0.793u 0.033s 0:00.83 98.7% 0+0k 0+0io 0pf+0w
> time exiftool -listw > t1
0.768u 0.045s 0:00.81 98.7% 0+0k 0+0io 0pf+0w
> time exiftool -list > t1
0.791u 0.033s 0:00.83 98.7% 0+0k 0+0io 0pf+0w
> time exiftool -listw > t1
0.794u 0.047s 0:00.84 98.8% 0+0k 0+0io 0pf+0w

The system time is consistently more than 0.01 sec longer, but the user time and total clock time aren't significantly different.

- Phil