Unable to start crawler using Java 17

[aayushL]

Hello, I am trying to run ache crawler and dump data in my elasticsearch database. But I am getting this error

`[2023-01-16 10:52:19,001]ERROR [main] (Main.java:261) - Crawler execution failed: java.lang.reflect.InaccessibleObjectException: Unable to make field private final java.lang.Object[] java.util.Arrays$ArrayList.a accessible: module java.base does not "opens java.util" to unnamed module @6fa4fbe3

java.lang.RuntimeException: java.lang.reflect.InaccessibleObjectException: Unable to make field private final java.lang.Object[] java.util.Arrays$ArrayList.a accessible: module java.base does not "opens java.util" to unnamed module @6fa4fbe3
at de.javakaffee.kryoserializers.ArraysAsListSerializer.(ArraysAsListSerializer.java:47)
at achecrawler.util.Kryos.registerDeserializers(Kryos.java:36)
at achecrawler.util.Kryos.access$000(Kryos.java:24)
at achecrawler.util.Kryos$1.initialValue(Kryos.java:29)
at achecrawler.util.Kryos$1.initialValue(Kryos.java:26)
at java.base/java.lang.ThreadLocal.setInitialValue(ThreadLocal.java:195)
at java.base/java.lang.ThreadLocal.get(ThreadLocal.java:172)
at achecrawler.util.Kryos.serializeObject(Kryos.java:58)
at achecrawler.util.persistence.rocksdb.StringObjectHashtable.put(StringObjectHashtable.java:20)
at achecrawler.util.persistence.PersistentHashtable.commit(PersistentHashtable.java:122)
at achecrawler.link.frontier.Frontier.commit(Frontier.java:28)
at achecrawler.link.frontier.FrontierManager.addSeeds(FrontierManager.java:254)
at achecrawler.link.frontier.FrontierManagerFactory.create(FrontierManagerFactory.java:44)
at achecrawler.link.LinkStorage.create(LinkStorage.java:169)
at achecrawler.crawler.async.AsyncCrawler.create(AsyncCrawler.java:114)
at achecrawler.crawler.CrawlersManager.createCrawler(CrawlersManager.java:104)
at achecrawler.Main$StartCrawl.run(Main.java:247)
at achecrawler.Main.main(Main.java:59)
Caused by: java.lang.reflect.InaccessibleObjectException: Unable to make field private final java.lang.Object[] java.util.Arrays$ArrayList.a accessible: module java.base does not "opens java.util" to unnamed module @6fa4fbe3
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:354)
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:297)
at java.base/java.lang.reflect.Field.checkCanSetAccessible(Field.java:180)
at java.base/java.lang.reflect.Field.setAccessible(Field.java:174)
at de.javakaffee.kryoserializers.ArraysAsListSerializer.(ArraysAsListSerializer.java:45)
... 17 common frames omitted
`
I am running following command:
ache startCrawl -c ./config/ache.yml -s ./config/sample.seeds -o ../data/ -e http://localhost:9200

[aecio]

It looks like you are using a recent Java version and not exporting the proper modules required by some crawler dependencies.

[aayushL]

Thank you for your reply.
For fixing this shall I downgrade my Java version? which version would be suitable?
or
Is there any other fix without downgrading Java?

[aecio]

I would expect it to work fine on Java 11 (the Docker version uses it). On recent Java versions, you can make modules accessible by adding flags --add-opens or --add-exports with the desired arguments to the java command. However, I'm not sure which values need to be passed as arguments to fix the specific problem you are reporting.

In ACHE, you can add these flags by setting the environment variable JAVA_OPTS before running the crawler. For example, in the Dockerfile we currently set JAVA_OPTS='-XX:+UseContainerSupport -XX:MaxRAMPercentage=80' to configure memory usage.

[aayushL]

Solved it by downgrading my java to java 11. Now its running perfectly fine.