The TaskQueue directly manages the TaskRunner. The main management loop runs
periodically and checks that the runner is doing reasonable things. If not, it
attempts to adjust the runner. The management loop also runs on-demand when a
task is added to keep task assignment relatively low latency. The TaskConsumer
is no longer necessary and so it no longer exists.
Task interval locks are handled differently. Instead of some tasks acquiring
locks at runtime and some tasks having implicit fixed lock intervals, all tasks
ask for locks explicitly. This occurs either in "isReady" (which runs on the
overlord) or in "run" (which runs on the peon).
Other changes:
- The TaskQueue is attached to the leader lifecycle, instead of global
- The TaskLockbox is able to sync itself from storage and is no longer
bootstrapped by the TaskQueue.
- RemoteTaskRunner does not clean up zk paths until asked to. This will
prevent deletion of statuses that have not yet been committed.
- Added retries on DbTaskStorage operations.
- Removed SpawnTasksAction (no more subtasks)
- Removed obsolete EventReceiverFirehose configs
- Removed obsolete OldOverlordResource
- Removed TaskStorageQueryAdapter methods related to subtasks
There are multiple and sundry changes in here.
First, "HadoopDruidIndexer" has been split into two pieces, (1) CliHadoop which pulls the hadoop version and builds up the right classpath with the proper hadoop version to run the indexer and (2) CliInternalHadoopIndexer which actually runs the indexer.
In order to work around a bunch of jets3t version conflicts with Hadoop and Druid, I needed to extract the S3 deep storage stuff into its own module. I then also moved the HDFS stuff into its own module so that I could eliminate the dependency on Hadoop for druid-server.
In doing these changes, I wanted to make the extensions buildable with only the druid-api jar, so a few other things had to move out of Druid and into druid-api. They are all API-level things, however, so they really belong in druid-api instead.
Lastly, I removed the druid-realtime module and put it all in druid-server.
