This is done by killing and respawning the jvms rather than reconnecting to existing
jvms, for a couple reasons. One is that it lets you restore tasks after server reboots
too, and another is that it lets you upgrade all the software on a box at once by just
restarting everything.
The main changes are,
1) Add "canRestore" and "stopGracefully" methods to Tasks that say if a task can
stop gracefully, and actually do a graceful stop. RealtimeIndexTask is the only
one that currently implements this.
2) Add "stop" method to TaskRunners that attempts to do an orderly shutdown.
ThreadPoolTaskRunner- call stopGracefully on restorable tasks, wait for exit
ForkingTaskRunner- close output stream to restorable tasks, wait for exit
RemoteTaskRunner- do nothing special, we actually don't want to shutdown
3) Add "restore" method to TaskRunners that attempts to bootstrap tasks from last run.
Only ForkingTaskRunner does anything here. It maintains a "restore.json" file with
a list of restorable tasks.
4) Have the CliPeon's ExecutorLifecycle lock the task base directory to avoid a restored
task and a zombie old task from stomping on each other.
add an EventReceiverFirehoseMonitor so that we can monitor how many
events have been queued in the EventReceiverFirehose and get a sense
about whether the firehose is under too much pressure.
1) Remove maven client from downloading extensions at runtime.
2) Provide a way to load Druid extensions and hadoop dependencies through file system.
3) Refactor pull-deps so that it can download extensions into extension directories.
4) Add documents on how to use this new extension loading mechanism.
5) Change the way how Druid tarball is generated. Now all the extensions + hadoop-client 2.3.0
are packaged within the Druid tarball.
this PR adds a JavaScriptWorkerSelectStrategy which allows defining
arbitrary logic for selecting workers to run task using a JavaScript
function.
This gives users full control to implement complex worker selection
strategies based on task attributes.
more tests and a complex javascript config
fix for java8 modify for nashorn compatibility
which could cause Guice duplicate binding errors.
Add unit test to replicate duplicate extension issue. Update documents. Add an package accessible getter for loadersMap for testing only.
Notice that extensions explicitly specified in druid.extensions.coordinates have a higher priority than ones included in the classpath.
Extension modules that don't have a canonical class name will be ignored.
Gian Merlino
Charles Allen
Parag Jain
Xavier Léauté
Bartosz Ługowski
Xavier Léauté
Bingkun Guo
Oleg Zaezdny
Fangjin Yang
Himanshu Gupta
jon-wei
pdeva
Zhihui Jiao
sahner
Zak Kristjanson
samjhecht
nishant