[FLINK-1492] Fix exceptions on blob store shutdown

[uce]

No description provided.

[rmetzger]

This change is also in 0.8 so do we need to apply the fix there as well for the upcoming 0.8.1 release?

[uce]

Yes, if it is finally OK.

[rmetzger]

Looks good.

[tillrohrmann]

What does this join do? I'm at a loss here.

[uce]

It's from the old code and I am not sure if it really needs to stay, but it ensures that the BlobServer thread really finishes when calling the shutdown method (BlobServer is a Thread and because the join is called from outside of the run method it waits for the BlobServer thread to finish).

[tillrohrmann]

Ah of course. Thanks for the clarification.

[tillrohrmann]

LGTM except for my single question.

[rmetzger]

I'll merge the change.

[uce]

OK, thanks. Just a reminder: we need to include this in 0.8.1 as well.

[mxm]

I still get

05:26:08,841 ERROR org.apache.flink.runtime.blob.BlobServer  - Error during shutdown of blob service via JVM shutdown hook: Shutdown in progress
java.lang.IllegalStateException: Shutdown in progress
at java.lang.ApplicationShutdownHooks.remove(ApplicationShutdownHooks.java:82)
at java.lang.Runtime.removeShutdownHook(Runtime.java:239)
at org.apache.flink.runtime.blob.BlobServer.shutdown(BlobServer.java:220)
at org.apache.flink.runtime.blob.BlobUtils$1.run(BlobUtils.java:210)
at java.lang.Thread.run(Thread.java:745)

On the last night's master.

[uce]

OK, thanks for reporting this. @StephanEwen has some pending changes to the blob manager and he will look into it as well.

It is not allowed to remove the shutdown hook when a shutdown is already in progress.

[uce]

The problem is totally deterministic when shutting down the job/task managers.

I've fixed it here: https://github.com/uce/incubator-flink/tree/flink-1492-fix_exceptions_really

@StephanEwen, if this is blocking the release vote, we should just merge my change and not wait for your changes in master, which touch the blob store.