runzhiwang commented on a change in pull request #709: HDDS-3244. Improve write
efficiency by opening RocksDB only once
URL: https://github.com/apache/hadoop-ozone/pull/709#discussion_r397568527
##########
File path:
hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/keyvalue/helpers/KeyValueContainerUtil.java
##########
@@ -73,14 +71,6 @@ public static void createContainerMetaData(File
containerMetaDataPath, File
throw new IOException("Unable to create directory for metadata storage."
+
" Path: " + containerMetaDataPath);
}
- MetadataStore store = MetadataStoreBuilder.newBuilder().setConf(conf)
- .setCreateIfMissing(true).setDbFile(dbFile).build();
Review comment:
@bshashikant @mukul1987
1. From the code, the [future
thread](https://github.com/apache/hadoop-ozone/blob/master/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/transport/server/ratis/ContainerStateMachine.java#L672)
do `getCachedStateMachineData ` in `readStateMachineData `and the [future
thread](https://github.com/apache/hadoop-ozone/blob/master/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/transport/server/ratis/ContainerStateMachine.java#L459)
do `createContainer` in `writeStateMachineData `are the same
[thread](https://github.com/apache/hadoop-ozone/blob/master/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/transport/server/ratis/ContainerStateMachine.java#L505).
Because `writeStateMachineData `called before `readStateMachineData`. So
leader must wait `createContainer `finish then `getCachedStateMachineData `and
append logs to the follower, so leader and follower are not independent,
follower must wait leader finish `createContainer`.
**How to improve it:**
I think this order can be improved by distinguishing the thread used by
`getCachedStateMachineData ` and `createContainer `, and if
[stateMachineDataCache.get(logIndex)](https://github.com/apache/hadoop-ozone/blob/master/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/transport/server/ratis/ContainerStateMachine.java#L617)
does not return null, leader and follower can be independent, but if it return
null, leader must finish createContaer than apennd logs to the follower. So I
think [data = readStateMachineData(requestProto, term,
logIndex)](https://github.com/apache/hadoop-ozone/blob/master/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/transport/server/ratis/ContainerStateMachine.java#L619)
should use the same thread with `createContainer` rather than the whole
[getCachedStateMachineData](https://github.com/apache/hadoop-ozone/blob/master/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/transport/server/ratis/ContainerStateMachine.java#L614).
What do you think ?
2. From the jaeger UI, you can also see follower create container after
leader finishing it.
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