PreparedGeometry::contains is not thread safe

[gauteh]

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Hi,

It seems that prepared geometry contains is not thread safe before run at least once. Easiest to provoke on large geometries. Not able to provoke on example in docs.

Regards, Gaute

[GuillaumeGomez]

Can you provide me a code having this issue so I can fix it and enforce it through tests please?

[gauteh]

https://github.com/gauteh/roaring-landmask/pull/6/files#diff-6423871468d8d2f4ebf2a85e879f9ba388c361b859c9191d62d4571685c95f58 , I think you need a big geometry for this to trigger.

[GuillaumeGomez]

Ok, I'll try to take a look when I have a bit of time.

[gauteh]

:+1: thanks. I can work around this atm by using a warmup call. It is most likely an upstream bug. But would be a pity to !Send/!Sync Geometry/PreparedGeometry just because of that.

[GuillaumeGomez]

Don't hesitate to take a look in the meantime. If yu can find a way to go around this limitation without removing Send and Sync, it'd be perfect. :)

[gauteh]

If we can afford a warmup call to contains, that is the only way I can think of at the moment (without fixing upstream). From the backtrace in geos it seems like the segfault happens somewhere in sorting of a vector in the geometry. I'll take a further look if(/when..?) I find the time!

On Wed, Sep 8, 2021 at 8:33 PM Guillaume Gomez @.***> wrote:

Don't hesitate to take a look in the meantime. If yu can find a way to go around this limitation without removing Send and Sync, it'd be perfect. :)

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[GuillaumeGomez]

Thanks, greatly appreciated! A bit under the water currently. ^^'

[gauteh]

No problem, thanks for the effort!

[gauteh]

In version 9 with geos 3.11 it is no longer reliable to warm up the prepared geometry to make it thread safe.