Shard Redis. (#539)

* Implement sharding in the Ray core

* Single node Python modifications to do sharding

* Do the sharding in redis.cc

* Pipe num_redis_shards through start_ray.py and worker.py.

* Use multiple redis shards in multinode tests.

* first steps for sharding ray.global_state

* Fix problem in multinode docker test.

* fix runtest.py

* fix some tests

* fix redis shard startup

* fix redis sharding

* fix

* fix bug introduced by the map-iterator being consumed

* fix sharding bug

* shard event table

* update number of Redis clients to be 64K

* Fix object table tests by flushing shards in between unit tests

* Fix local scheduler tests

* Documentation

* Register shard locations in the primary shard

* Add plasma unit tests back to build

* lint

* lint and fix build

* Fix

* Address Robert's comments

* Refactor start_ray_processes to start Redis shard

* lint

* Fix global scheduler python tests

* Fix redis module test

* Fix plasma test

* Fix component failure test

* Fix local scheduler test

* Fix runtest.py

* Fix global scheduler test for python3

* Fix task_table_test_and_update bug, from actor task table submission race

* Fix jenkins tests.

* Retry Redis shard connections

* Fix test cases

* Convert database clients to DBClient struct

* Fix race condition when subscribing to db client table

* Remove unused lines, add APITest for sharded Ray

* Fix

* Fix memory leak

* Suppress ReconstructionTests output

* Suppress output for APITestSharded

* Reissue task table add/update commands if initial command does not publish to any subscribers.

* fix

* Fix linting.

* fix tests

* fix linting

* fix python test

* fix linting

src/plasma/test/run_tests.sh

@@ -9,11 +9,18 @@ sleep 1
 killall plasma_store
 ./src/plasma/serialization_tests
 
-./src/common/thirdparty/redis/src/redis-server --loglevel warning --loadmodule ./src/common/redis_module/libray_redis_module.so &
-redis_pid=$!
+# Start the Redis shards.
+./src/common/thirdparty/redis/src/redis-server --loglevel warning --loadmodule ./src/common/redis_module/libray_redis_module.so --port 6379 &
+redis_pid1=$!
+./src/common/thirdparty/redis/src/redis-server --loglevel warning --loadmodule ./src/common/redis_module/libray_redis_module.so --port 6380 &
+redis_pid2=$!
 sleep 1
-# flush the redis server
-./src/common/thirdparty/redis/src/redis-cli flushall &
+
+# Flush the redis server
+./src/common/thirdparty/redis/src/redis-cli flushall
+# Register the shard location with the primary shard.
+./src/common/thirdparty/redis/src/redis-cli set NumRedisShards 1
+./src/common/thirdparty/redis/src/redis-cli rpush RedisShards 127.0.0.1:6380
 sleep 1
 ./src/plasma/plasma_store -s /tmp/store1 -m 1000000000 &
 plasma1_pid=$!
@@ -31,5 +38,7 @@ kill $plasma4_pid
 kill $plasma3_pid
 kill $plasma2_pid
 kill $plasma1_pid
-kill $redis_pid
-wait $redis_pid
+kill $redis_pid1
+wait $redis_pid1
+kill $redis_pid2
+wait $redis_pid2