Exception in thread "bloop-server-background" java.lang.NoClassDefFoundError

[vikas-saxena02]

Hi all,
I am new to Metals and VSCode but have been using maven to do my scala builds for a long time.
I have been trying to get metals server up and running in an air-gapped system which has connectivity to corporate JFrog artifactory server. Coursier Mirror and Custom repositories have been setup and all dependencies have been sorted out.
However, I am unable to get the Metals serer started. Below are system details and error that I am getting.

• OS: RHEL 7
• java version: JDK-11 (JAVA_HOME is setup correctly)
• VS Code version: 1.85.2
• Metals version: 1.2
• Plugin version: 1.27.0 installed through VSIX

Error
`
2024.02.09 18:02:14 INFO [INFO] SUCCESS: org.apache.parquet:parquet-jackson:jar:1.12.3:provided (sources = true)
2024.02.09 18:02:14 INFO [INFO] Resolving artifact: com.google.protobuf:protobuf-java:jar:3.21.12:provided (sources = false)
2024.02.09 18:02:14 INFO [INFO] SUCCESS: com.google.protobuf:protobuf-java:jar:3.21.12:provided (sources = false)
2024.02.09 18:02:14 INFO [INFO] Resolving artifact: com.google.protobuf:protobuf-java:jar:3.21.12:provided (sources = true)
2024.02.09 18:02:14 INFO [INFO] SUCCESS: com.google.protobuf:protobuf-java:jar:3.21.12:provided (sources = true)
2024.02.09 18:02:14 INFO [INFO] Generated .bloop/SampleSparkProject-test.json
2024.02.09 18:02:14 INFO [INFO] ------------------------------------------------------------------------
2024.02.09 18:02:14 INFO [INFO] BUILD SUCCESS
2024.02.09 18:02:14 INFO [INFO] ------------------------------------------------------------------------
2024.02.09 18:02:14 INFO [INFO] Total time: 03:40 min
2024.02.09 18:02:14 INFO [INFO] Finished at: 2024-02-09T18:02:14+11:00
2024.02.09 18:02:14 INFO [INFO] ------------------------------------------------------------------------
2024.02.09 18:02:14 INFO time: ran 'mvn bloopInstall' in 3m43s
2024.02.09 18:02:15 INFO Attempting to connect to the build server...
2024.02.09 18:02:15 INFO Setting up current java home /opt/java/jdk-11 in /home/svikas/.bloop/bloop.json
Exception in thread "bloop-server-background" java.lang.NoClassDefFoundError: com/github/plokhotnyuk/jsoniter_scala/core/JsonValueCodec
at bloop.bloopgun.util.Environment$.bloopGlobalSettings(Environment.scala:31)
at bloop.bloopgun.BloopgunCli.startServer(Bloopgun.scala:543)
at bloop.bloopgun.BloopgunCli$FireInBackground$.$anonfun$fire$1(Bloopgun.scala:314)
at bloop.bloopgun.core.Shell$$anon$2.run(Shell.scala:154)
Caused by: java.lang.ClassNotFoundException: com.github.plokhotnyuk.jsoniter_scala.core.JsonValueCodec
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:582)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
... 4 more
Exception in thread "bloop-server-background" java.lang.NoClassDefFoundError: com/github/plokhotnyuk/jsoniter_scala/core/JsonValueCodec
at bloop.bloopgun.util.Environment$.bloopGlobalSettings(Environment.scala:31)
at bloop.bloopgun.BloopgunCli.startServer(Bloopgun.scala:543)
at bloop.bloopgun.BloopgunCli$FireInBackground$.$anonfun$fire$1(Bloopgun.scala:314)
at bloop.bloopgun.core.Shell$$anon$2.run(Shell.scala:154)
Caused by: java.lang.ClassNotFoundException: com.github.plokhotnyuk.jsoniter_scala.core.JsonValueCodec
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:582)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
... 4 more

2024.02.09 18:08:58 ERROR > Attempting a connection to the server...
2024.02.09 18:08:58 ERROR > Attempting a connection to the server...
2024.02.09 18:08:58 ERROR > Attempting a connection to the server...
2024.02.09 18:08:58 ERROR > Attempting a connection to the server...
2024.02.09 18:08:58 ERROR > Attempting a connection to the server...
2024.02.09 18:08:58 ERROR > Attempting a connection to the server...
2024.02.09 18:08:58 ERROR > Attempting a connection to the server...
2024.02.09 18:08:58 ERROR > Attempting a connection to the server...
2024.02.09 18:08:58 ERROR error: The launcher failed to establish a bsp connection, aborting...
2024.02.09 18:08:59 ERROR Failed to connect with build server, no functionality will work.
java.lang.RuntimeException: The server did not start, got FailedToOpenBspConnection
at bloop.launcher.LauncherMain.failPromise$1(Launcher.scala:92)
at bloop.launcher.LauncherMain.runLauncher(Launcher.scala:119)
at scala.meta.internal.metals.BloopServers$$anon$2.run(BloopServers.scala:501)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.lang.Thread.run(Thread.java:834)
`

Can I please get some help here what is causing the ClassNotFoundException here?

[vikas-saxena02]

@tgodzik any inputs?

[tgodzik]

Looks like we are missing one of the libraries for bloop. You might try downloading bloop frontend jars also.

We have an utility main class in metals that should do it.

[vikas-saxena02]

@tgodzik we do not have bloop locally installed and using the bootstrap version that comes with it. Can the utility main class still be used? Can you please point me to the documentation on utility main class so that I can figure out on how to use it?

[tgodzik]

I meant using https://github.com/scalameta/metals/blob/main/metals/src/main/scala/scala/meta/metals/DownloadDependencies.scala

This should download all the base jars to the coursier cache, which can then be copied over.

[vikas-saxena02]

@tgodzik there seems to weird things happening here. Seems like if I explicitly tell Metals to use my local maven installation mvn bloopInstall downloads everything in ~/.m2/repository folder instead of ~/.cache/coursier and metals gets the ClassNotFoundException as the dependnecies are present elsewhere, I am going to try using the bootstrap version of maven that comes with metals to see if the problem still persists

[tgodzik]

Maven has a different place for dependencies, but those downloaded using bloopInstall are only needed for the project itself, not for Metals or Bloop. I would suggest using coursier to download those.

[vikas-saxena02]

All good @tgodzik seems like bloop server kills itself if your maven dependency resolution does not occur due to dependencies missing in local artifactory.
Everything is working as expected. Thanks for the help.