[jira] [Comment Edited] (FOP-3172) image-loading configuration settings are not thread-safe

["Peter Hull (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FOP-3172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17832411#comment-17832411 ] 

Peter Hull edited comment on FOP-3172 at 3/30/24 8:42 AM:
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I had a little dig into this. As I understand it, creating a FopFactory creates a FopFactoryBuilder, which in turn creates a FopFactoryConfigImpl. FopFactoryConfigImpl creates an ImageManager. The ImageManager stores data, including the  'Additional Penalties' which are the issue here, in ImageImplRegistry, which is a singleton class. So ultimately it's this single instance that is responsible for the carry-over of properties from one FopFactory to the next, and it doesn't seem like there is a simple way to avoid that.

 

 
{code:java}
    @Test
    public void testCarryOver() throws Exception {
        URI baseURI = URI.create("http://example.com/");
        String className = SequentialTest.class.getName();
        FopFactory fopFactory1 = FopFactory.newInstance(baseURI);
        fopFactory1.getImageManager().getRegistry().setAdditionalPenalty(className, Penalty.toPenalty(1234));
        FopFactory fopFactory2 = FopFactory.newInstance(baseURI);
        Penalty expected = Penalty.ZERO_PENALTY;
        Penalty actual = fopFactory2.getImageManager().getRegistry().getAdditionalPenalty(className);
        // For a 'fresh' FopFactory, penalty should be the default, zero.
        org.junit.Assert.assertEquals(expected, actual);
        // in fact it fails because 1234 is carried over from fopFactory1 to fopFactory2.
    }
 {code}
 

 

For reference the classes are,
 * org.apache.xmlgraphics.image.loader.spi.ImageImplRegistry in xmlgraphics-commons-2.9.jar
 * org.apache.xmlgraphics.image.loader.ImageManager in in xmlgraphics-commons-2.9.jar
 * org.apache.fop.apps.FopFactoryBuilder in fop-core-2.9.jar
 * org.apache.fop.apps.FopConfParser in fop-core-2.9.jar


was (Author: peterhull90):
I had a little dig into this. As I understand it, creating a FopFactory creates a FopFactoryBuilder, which in turn creates a FopFactoryConfigImpl. FopFactoryConfigImpl creates an ImageManager. The ImageManager stores data, including the  'Additional Penalties' which are the issue here, in ImageImplRegistry, which is a singleton class. So ultimately it's this single instance that is responsible for the carry-over of properties from one FopFactory to the next, and it doesn't seem like there is a simple way to avoid that.

For reference the classes are,
 * org.apache.xmlgraphics.image.loader.spi.ImageImplRegistry in xmlgraphics-commons-2.9.jar
 * org.apache.xmlgraphics.image.loader.ImageManager in in xmlgraphics-commons-2.9.jar
 * org.apache.fop.apps.FopFactoryBuilder in fop-core-2.9.jar
 * org.apache.fop.apps.FopConfParser in fop-core-2.9.jar

> image-loading configuration settings are not thread-safe
> --------------------------------------------------------
>
>                 Key: FOP-3172
>                 URL: https://issues.apache.org/jira/browse/FOP-3172
>             Project: FOP
>          Issue Type: Bug
>          Components: image/unqualified
>    Affects Versions: 2.9
>            Reporter: Martin Leitner
>            Priority: Major
>         Attachments: fop_3172.zip
>
>
> As a workaround for FOP-3171 I added an <image-loading> section to the config and noticed that the settings will take effect on all subsequent renderings in the same VM, even when they use a different config or none at all. When running two or more rendering processes with different configs in parallel, the result will basically be random.
> At the very least, this behaviour should be documented and warned about.



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