Java fails to start when classes.tar is not loaded via the vfs tar plugin

[Sebastian Sumpf]

Hello Pirmin,

On 11/20/19 5:33 PM, Duss Pirmin wrote:
> Hello Genodians
> 
> I'm tying to optimize the startup time of a java application (ARM
> board), as starting the JVM takes several seconds on our board.
> 
> To do this, I tried to move the classes.tar in to a separate vfs
> component [1]. This crashes the JVM with the following error message:
> 
> [init -> java] Error occurred during initialization of VM
> [init -> java] java.lang.NoClassDefFoundError:
> java/util/concurrent/ConcurrentHashMap
> [init -> java] 	at
> java.lang.WeakPairMap.<init>(java.base/WeakPairMap.java:47)
> [init -> java] 	at java.lang.Module.<clinit>(java.base/Module.java:267)
> 
> Can anyone tell me, why this happens?
> Is there a way to fix this?
> 
> [1]
> https://github.com/trimpim/genode-world/commit/3ec7d915e20576a786a3e89decb494a7dc2c275f

I have tried to reproduce your issue by applying your commit and testing
it on base-hw in Qemu (pbxa9). This worked so far. The
'NoClassDefFoundError' usually occurs if something goes wrong during
class compilation or dependency loading, or something is corrupt. If
Java could not find a class it would throw a 'ClassNotFoundException'.

Regards,

Sebastian



-- 
Sebastian Sumpf
Genode Labs

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