Server running on Oraclelinux8

Docker: FROM openjdk:17-oraclelinux8

Dockerfile: https://github.com/wwlib/docker-minecraft/blob/master/minecraft-server-1.18.1-openjdk17/Dockerfile.openjdk17

README: https://github.com/wwlib/docker-minecraft/blob/master/minecraft-server-1.18.1-openjdk17/README.md

java --version
openjdk 17.0.1 2021-10-19
OpenJDK Runtime Environment (build 17.0.1+12-39)
OpenJDK 64-Bit Server VM (build 17.0.1+12-39, mixed mode, sharing)

Nashorn 15.3 (JavaScript engine) is loaded as a module via:

java -Xms512M -Xmx1G -cp /minecraft/nashorn --module-path /minecraft/nashorn --add-modules org.openjdk.nashorn -jar spigot-1.18.1.jar 

Update re: Grakkit

Just an FYI unrelated to the original issue (but interesting)

It turns out that Grakkit DOES work in 1.18.1 when using openjdk17 WITHOUT GraalVM: i.e. openjdk:17-oraclelinux8

(https://github.com/wwlib/docker-minecraft/blob/master/minecraft-server-1.18.1-openjdk17/Dockerfile.openjdk17)

It turns out that Grakkit does not use ScriptEngine. It packages and shades the GraalJS library and uses those classes.

What does not work is the combo of GraalVM CE 21.3.0 (ghcr.io/graalvm/graalvm-ce:java17-21.3) + 1.18.1 + Grakkit.

Great. Thanks, again.

• Yes
• Not sure, see 'Library Loader' in plugin.yml: https://www.spigotmc.org/threads/spigot-bungeecord-1-17-1-17-1.510208/#post-4184317
• Yes

Checking to see if I understand:

• Shaded script engine

• • Do you mean packaging the plugin so its dependencies are shaded?
• Library loaded script
  • Assume this is what Grakkit does by including the GraalVM classes in its plugin jar
• Module loaded script engine
  • Assume this refers to loading Nashorn 15.3 - as a module:
    • --module-path /minecraft/nashorn --add-modules org.openjdk.nashorn

Do any of these describe the script engine included in the GraalVM openjdk 17 distribution? 

"Module loaded script engine is now fixed" this sounds promising, though maybe temporary.

I dug into this for you, and the situation is:

• Shaded script engine works as normal
• Library loaded script engine doesn't work due to SPIGOT-6904
• Module loaded script engine is now fixed (though I would discourage this, I don't like the behaviour and may remove it once SPIGOT-6904 is fixed)

(Cross-posted. Just seeing your previous reply.)

"The main spigot-1.18.jar is now a bootstrap jar which contains all libraries." etc.

"I suggest you ask the forums for help"

OK, will do.

Thanks for the help. 

FYI: I just tested another plugin (grakkit) that uses JavaScript by including GraalVM dependencies in its plugin jar (grakkit-5.0.4.paper.jar).

https://github.com/grakkit/grakkit

Same issue. Grakkit works in spigot-1.17.1 but fails in spigot-1.18.1 (also fails using paper-1.18.1-155.jar)

[21:32:21] [Server thread/WARN]: [grakkit] Task #2 for grakkit v5.0.4 generated an exception
java.lang.NullPointerException: Cannot invoke "grakkit.FileInstance.tick()" because "grakkit.Grakkit.driver" is null
        at grakkit.Grakkit.tick(Grakkit.java:93) ~[grakkit-5.0.4.paper.jar:?]
        at org.bukkit.craftbukkit.v1_18_R1.scheduler.CraftTask.run(CraftTask.java:82) ~[spigot-1.18.1-R0.1-SNAPSHOT.jar:3405-Spigot-f4ff00f-d10c35e]
        at org.bukkit.craftbukkit.v1_18_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:415) ~[spigot-1.18.1-R0.1-SNAPSHOT.jar:3405-Spigot-f4ff00f-d10c35e]
        at net.minecraft.server.MinecraftServer.b(MinecraftServer.java:1255) ~[spigot-1.18.1-R0.1-SNAPSHOT.jar:3405-Spigot-f4ff00f-d10c35e]
        at net.minecraft.server.dedicated.DedicatedServer.b(DedicatedServer.java:428) ~[spigot-1.18.1-R0.1-SNAPSHOT.jar:3405-Spigot-f4ff00f-d10c35e]
        at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:1206) ~[spigot-1.18.1-R0.1-SNAPSHOT.jar:3405-Spigot-f4ff00f-d10c35e]
        at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:1034) ~[spigot-1.18.1-R0.1-SNAPSHOT.jar:3405-Spigot-f4ff00f-d10c35e]
        at net.minecraft.server.MinecraftServer.lambda$0(MinecraftServer.java:304) ~[spigot-1.18.1-R0.1-SNAPSHOT.jar:3405-Spigot-f4ff00f-d10c35e]

Bootstrap Jar
The main spigot-1.18.jar is now a bootstrap jar which contains all libraries. You cannot directly depend on this jar. You should depend on Spigot/Spigot-API/target/spigot-api-1.18-R0.1-SNAPSHOT-shaded.jar, or the entire contents of the bundler directory from your server, or use a dependency manager such as Maven or Gradle to handle this automatically.

Please read the release notes for further information: https://www.spigotmc.org/threads/9-years-of-spigotmc-spigot-bungeecord-1-18-1-18-1-release.534760/#post-4305163

I suggest you ask the forums for help, as I do not believe there to be any Spigot bug. If you believe there is a bug with how Spigot loads classes (unlikely), then please create a minimal test case using one of the supported methods (shaded jar, library loader). It is outside the scope of a bug report here to debug the entirety of Nashorn (especially when loaded in an unsupported manner).

For reference (completeness) the same issue happens when running spigot-1.18.1 using GraalVM (openjdk17 + Graal Script Engine)
 
Using container image: ghcr.io/graalvm/graalvm-ce:java17-21.3 from https://github.com/graalvm/container/pkgs/container/graalvm-ce
 
Dockerfile:
https://github.com/wwlib/docker-minecraft/blob/master/minecraft-server-1.18.1-openjdk17/Dockerfile.openjdk17-graalvm
 

java --version
openjdk 17.0.1 2021-10-19
OpenJDK Runtime Environment GraalVM CE 21.3.0 (build 17.0.1+12-jvmci-21.3-b05)
OpenJDK 64-Bit Server VM GraalVM CE 21.3.0 (build 17.0.1+12-jvmci-21.3-b05, mixed mode, sharing)

When running GraalVM (openjdk17) Minecraft 1.17.1 CAN access the JavaScript script engine.

1.17.1

java -Xms512M -Xmx1G -jar spigot-1.17.1.jar

[19:20:06] [Worker-Main-10/INFO]: Preparing spawn area: 91%
[19:20:06] [Server thread/INFO]: Time elapsed: 3874 ms
[19:20:06] [Server thread/INFO]: [hellojavascript] Enabling hellojavascript v0.1
[19:20:06] [Server thread/ERROR]: [hellojavascript] HelloJavaScript plugin enabled.
[19:20:06] [Server thread/ERROR]: [hellojavascript] VM Details:
[19:20:06] [Server thread/ERROR]: [hellojavascript] OpenJDK 64-Bit Server VM
[19:20:06] [Server thread/ERROR]: [hellojavascript] 17.0.1+12-jvmci-21.3-b05
[19:20:06] [Server thread/ERROR]: [hellojavascript] mixed mode, sharing
[19:20:07] [Server thread/ERROR]: [hellojavascript] Found a JavaScript engine.
[19:20:07] [Server thread/INFO]: Server permissions file permissions.yml is empty, ignoring it
[19:20:07] [Server thread/INFO]: Done (35.591s)! For help, type "help"

When running GraalVM (openjdk17) Minecraft 1.18.1 CANNOT access the JavaScript script engine.

1.18.1

java -Xms512M -Xmx1G -jar spigot-1.18.1.jar

[19:29:50] [Worker-Main-8/INFO]: Preparing spawn area: 97%
[19:29:51] [Server thread/INFO]: Time elapsed: 7584 ms
[19:29:51] [Server thread/INFO]: [hellojavascript] Enabling hellojavascript v0.1
[19:29:51] [Server thread/ERROR]: [hellojavascript] HelloJavaScript plugin enabled.
[19:29:51] [Server thread/ERROR]: [hellojavascript] VM Details:
[19:29:51] [Server thread/ERROR]: [hellojavascript] OpenJDK 64-Bit Server VM
[19:29:51] [Server thread/ERROR]: [hellojavascript] 17.0.1+12-jvmci-21.3-b05
[19:29:51] [Server thread/ERROR]: [hellojavascript] mixed mode, sharing
[19:29:51] [Server thread/ERROR]: [hellojavascript] No JavaScript Engine available.
[19:29:51] [Server thread/ERROR]: [hellojavascript] Available engines include:
[19:29:51] [Server thread/INFO]: Server permissions file permissions.yml is empty, ignoring it
[19:29:51] [Server thread/INFO]: Done (103.668s)! For help, type "help"
 
 
@md_5: Is this also explained by: "the Spigot jars are not loaded into the system classloader" and is this because class loading has changed between 1.17.1 and 1.18.1 ?

OK. Can you confirm that this is a change from 1.17.1 since it worked there.

I will look into loading Nashorn using the library loader, as you suggest.

And just to make sure I am seeing all the release notes, I have reviewed the notes here:

https://www.spigotmc.org/threads/9-years-of-spigotmc-spigot-bungeecord-1-18-1-18-1-release.534760/

And looked at the diff here:

https://hub.spigotmc.org/stash/projects/SPIGOT/repos/bukkit/compare/diff?targetBranch=d32e3c764edd6a449ddd220720185d266c2193f9&sourceBranch=refs%2Fheads%2Fmaster&targetRepoId=11

Are there other notes? I did not see a mention of a plugin loading change - at least not a breaking change. (But I am new to this)

Thanks.

As per the release notes, the Spigot jars are not loaded into the system classloader, but rather their own classloader. Your code (which is manipulating classloaders) needs to be modified accordingly. Based on the information you have provided there does not appear to be any Spigot bug.

Consider using the library loader.