[gdal-dev] GDAL + Docker with NFS

[Andrew C Aitchison]

On Sun, 18 Mar 2018, Ouwen Huang wrote:

> I feel quite silly, but it seems that the `gdal.Open` was actually opening
> the file from the docker mounted NFS, just very slowly. I left it to run
> for 2 minutes or so and it returned.
>
> But this is weird behavior because on the host a `*Dataset` was returned
> instantly, and within the docker container running `cp
> /mnt/efs/<my_geo.tiff>  <docker_local_dir` is also instant. The 2min
> latency seems to only occur within a docker mounted network filesystem for
> the `gdal.Open` command.
>
> Some other findings, the `/mnt/efs/` directory i'm using has several files
> (100k+). When I move the geotiff under a new directory within EFS
> (`mnt/efs/test`), the `gdal.Open` command is instant within the docker
> container.
>
> Is there a reason why `gdal.Open` is slow for a cluttered directory but
> unix `cp` is not?

http://www.gdal.org/classGDALOpenInfo.html
talks about "sibling" files; that is other files in the same directory.
These are opened at the same time for some reason.

https://trac.osgeo.org/gdal/ticket/2158 suggests that the environment 
variable GDAL_DISABLE_READDIR_ON_OPEN should disable this.


-- 
Andrew C. Aitchison					Cambridge, UK
 			andrew at aitchison.me.uk