[HDFS-16953] RBF: Mount table store APIs should update cache only if state store record is successfully updated

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.4.0
• Fix Version/s: 3.4.0
• Component/s: rbf
• Labels: pull-request-available
• Target Version/s: 3.4.0
• Hadoop Flags: Reviewed
• Assignee: Viraj Jasani
• Reporter: Viraj Jasani
• Created: 16/Mar/23 00:14
• Updated: 28/Jan/24 07:12
• Resolved: 18/Mar/23 21:44

Description

RBF Mount table state store APIs addMountTableEntry, updateMountTableEntry and removeMountTableEntry performs cache refresh for all routers regardless of the actual record update result. If the record fails to get updated on zookeeper/file based store impl, reloading the cache for all routers would be unnecessary.

 

For instance, simultaneously adding new mount point could lead to failure for the second call if first call has not added new entry by the time second call retrieves mount table entry from getMountTableEntries before attempting to call addMountTableEntry.

DEBUG [{cluster}/{ip}:8111] ipc.Client - IPC Client (1826699684) connection to nn-0-{ns}.{cluster}/{ip}:8111 from {user}IPC Client (1826699684) connection to nn-0-{ns}.{cluster}/{ip}:8111 from {user} sending #1 org.apache.hadoop.hdfs.protocolPB.RouterAdminProtocol.addMountTableEntry

DEBUG [{cluster}/{ip}:8111 from {user}] ipc.Client - IPC Client (1826699684) connection to nn-0-{ns}.{cluster}/{ip}:8111 from {user} got value #1

DEBUG [main] ipc.ProtobufRpcEngine2 - Call: addMountTableEntry took 24ms

DEBUG [{cluster}/{ip}:8111 from {user}] ipc.Client - IPC Client (1826699684) connection to nn-0-{ns}.{cluster}/{ip}:8111 from {user}: closed

DEBUG [{cluster}/{ip}:8111 from {user}] ipc.Client - IPC Client (1826699684) connection to nn-0-{ns}.{cluster}/{ip}:8111 from {user}: stopped, remaining connections 0

TRACE [main] ipc.ProtobufRpcEngine2 - 1: Response <- nn-0-{ns}.{cluster}/{ip}:8111: addMountTableEntry {status: false}

Cannot add mount point /data503 

The failure to write new record:

INFO  [IPC Server handler 0 on default port 8111] impl.StateStoreZooKeeperImpl - Cannot write record "/hdfs-federation/MountTable/0SLASH0data503", it already exists 

Since the successful call has already refreshed cache for all routers, second call that failed should not have refreshed cache for all routers again as everyone already has updated records in cache.

Issue Links

• links to: GitHub Pull Request #5482