undefined method 'new_from_file' for Vips::Image:Class

[tomasc]

I am getting errors such as undefined method 'new_from_file' for Vips::Image:Class or uninitialized constant Vips::Image from here, seemingly randomly:

https://github.com/tomasc/dragonfly_libvips/blob/master/lib/dragonfly_libvips/processors/thumb.rb#L24

vips is required, I have vips-8.5.2 installed (Ubuntu 14), with gobject-introspection (3.1.1), ruby-vips (1.0.4)

Can't seem to track down the source of the issue … any ideas please?

Thanks,
Tomas

[jcupitt]

You mean sometimes it works, sometimes not?

#98 sounds a little similar. That was (I think) to do with the way the vips gem handles startup. Maybe try adding something to trigger initialization earlier? You could try adding

x = Vips::Image.black 1, 1

Just after the require "vips".

[tomasc]

Thank John, yes looks a bit like #98. I will try your suggestion and report back.

[jcupitt]

On another point, have you looked at the thumbnail method added in 8.5? It should be a lot faster than the resize you are using now.

http://jcupitt.github.io/libvips/API/current/libvips-resample.html#vips-thumbnail

[jcupitt]

For example, shrink a 9400 x 9400 pixel jpg down to 94 pixels across:

$ time vips resize wtc.jpg x.jpg 0.01
real	0m1.732s
user	0m1.708s
sys	0m0.020s
$ time vips thumbnail wtc.jpg x.jpg 94
real	0m0.326s
user	0m0.320s
sys	0m0.000s

thumbnail also supports lots of useful image shrink features, like auto-rotate and smartcrop.

[tomasc]

great, will update to that!

BTW I moved the require in the method close to where the class is used and it does seem to stop the errors (https://github.com/tomasc/dragonfly_libvips/blob/master/lib/dragonfly_libvips/processors/thumb.rb#L23) – but let me give it more time before we close this

[tomasc]

BTW2 @jcupitt – this is a feature of 8.5.x vips, correct? If so, is there going to be updated OS X homebrew formula? (latest seem to be 8.4.5)

[jcupitt]

Yes, there's an updated formula in the queue for approval, they've just not merged it yet:

https://github.com/Homebrew/homebrew-science/pull/5399

The CI is failing, but I think that's not vips.rb's fault, it looks like pycairo is broken at the moment.

[tomasc]

I see, thank you!

[jcupitt]

Is there a performance hit from having the require there? As long as vips is only loaded once, sure!

Did you try initing vips on require (put some not-useful call to vips in just after the require)?

[tomasc]

I believe subsequent calls to require in Ruby should have no effect as long as the file is already loaded.

[tomasc]

BTW3 that speed gain of thumbnail looks awesome!

[jcupitt]

... the way vips init works, not much happens when the require runs, it just loads the typelib and adds some hooks. The first time you try to access a vips constant or method, the introspection fires and the rest of the binding is built.

You can see the logic here:

https://github.com/jcupitt/ruby-vips/blob/master/lib/vips.rb#L44

So ... if you require, then freeze the ruby process, then fork() for each request (at least rails does this, don't know about dragonfly) you will trigger the init as part of each request process, and perhaps have terrible confusion and breakage.

If you init after require, vips will be loaded up and ready to go when the request comes in, and can never be run from more than one context.

[jcupitt]

The thumbnail speed gain mostly comes from it exploiting shrink on load features in the supported libraries. You'll see even more for PDF or SVG, but little improvement for TIFF or PNG.

JPG gives a very nice speedup, and it's probably the most common case, so that's great.

[tomasc]

when I do

require 'vips'
Vips::Image.black 1, 1

at the top of the file I get

GLib-CRITICAL **: g_hash_table_lookup: assertion 'hash_table != NULL' failed
	from /Users/tomascelizna/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/gobject-introspection-3.1.1/lib/gobject-introspection/loader.rb:110:in `block in define_singleton_method'
	from /Users/tomascelizna/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/ruby-vips-1.0.4/lib/vips/call.rb:173:in `build'
	from /Users/tomascelizna/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/ruby-vips-1.0.4/lib/vips/call.rb:249:in `invoke'
	from /Users/tomascelizna/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/ruby-vips-1.0.4/lib/vips/call.rb:278:in `call_base'
	from /Users/tomascelizna/.rbenv/versions/2.3.3/lib/ruby/gems/2.3.0/gems/ruby-vips-1.0.4/lib/vips/image.rb:452:in `new_from_file'