Started on 2.1.4 release notes

_posts/release/2025-04-08-accumulo-2.1.4.md

@@ -0,0 +1,111 @@
+---
+title: Apache Accumulo 2.1.4
+sortableversion: '02.01.04'
+draft: true
+LTM: true
+---
+## About
+
+Apache Accumulo 2.1.4 is a patch release of the 2.1 LTM line. It contains bug
+fixes and minor enhancements. This version supersedes earlier 2.1 releases
+and users upgrading to 2.1 should upgrade directly to this version instead of
+any prior 2.1 release.
+
+## Notable Changes
+
+* {% ghi 5446 %} Many dependencies were updated, to include protobuf-java which
+  was updated from 3.22.0 to 3.25.6 due to a vulnerability. Users may run into
+  a runtime exception added in https://github.com/protocolbuffers/protobuf/pull/20084
+  when using old generated Protobuf files. Users may need to address any compatibility issues
+  with this version of protobuf-java, if their code also makes use of this library.
+* {% ghi 5073 %} {% ghi 5034 %} Added `accumulo check-accumulo-properties` command that can be
+  run before an instance is initialized to check the properties file.
+* {% ghi 5193 %} Added `accumulo admin signalShutdown` command to signal the server
+  process to initiate a graceful shutdown. Compactors will finish the major compaction
+  that they are currently working on, then will exit. Scan Servers will return a busy
+  signal to all clients for new scan requests, and will shutdown when all in-progress
+  scans have closed. Tablet Servers will signal the Manager that they are shutting down,
+  which should prevent assignment of tablets to that server, then they will unload all
+  tablets and shut down. The Monitor, Manager, GarbageCollector, and CompactionCoordinator
+  will shut down also. The last step in the shutdown process for all servers is to remove
+  their lock in ZooKeeper.
+* {% ghi 5438 %} Added `accumulo upgrade --prepare` command which should be used after
+  shutting down an instance in preparation for an upgrade. This will check that no Fate
+  transactions exist, delete any ZooKeeper locks for server processes, and prohibit any
+  server processes from being started.
+* {% ghi 4898 %} New way to compute bulk load plans (TODO: Needs text)
+* {% ghi 5169 %} {% ghi 5170 %} The TabletServer will halt itself when a walog write or
+  minc failure occurs and the TabletServer lock is not held in ZooKeeper.
+* {% ghi 5145 %} {% ghi 5132 %} The Manager and TabletServer processes now have a background
+  thread that can be enabled via the property `general.server.lock.verification.interval` to
+  validate that the process is holding the lock in ZooKeeper. The existing mechanism of relying
+  on a Watcher to notify the process that the lock has been lost can be a problem due to the
+  fact that there is a single thread in the ZooKeeper client that fires Watcher events. If the
+  thread is currently waiting on a hung Watcher, then subsequent Watcher events will not fire
+  and could leave the server running without a lock.
+* {% ghi 5174 %} Improvements to the `accumulo-cluster` and `accumulo-service` scripts have been
+  backported from the main branch. This includes syntax changes. Users should review the scripts
+  for changes that may effect them.
+
+### Configuration Improvements
+
+* {% ghi 4723 %} {% ghi 5239 %} Changes to properties `tserver.session.idle.max` and
+  `tserver.session.update.idle.max` no longer require a TabletServer restart.
+* {% ghi 5397 %} {% ghi 5399 %} Added property `gc.threads.delete.wal` to control the number of threads to use for
+  deleting write-ahead logs and recovery files.
+* {% ghi 5341 %} Created an optimization in Bulk Import v2 to enable faster processing of bulk import files
+  when loading into a sparse set of tablets in a large table. See new table property `table.bulk.metadata.skip.distance`.
+
+### Notable Bug Fixes
+
+* {% ghi 5033 %} {% ghi 5038 %} Group names in cluster.yaml must conform to bash variable name rules
+  or an error will be raised when parsing the cluster.yaml file.
+* {% ghi 5221 %} The shell will now print to stdout, instead of stderr, when there is no terminal set. This
+  will help with piping the output of the shell to other commands such as grep.
+* {% ghi 5396 %} Modified `accumulo-cluster` to stop GC and ScanServer processes first when stopping the
+  cluster. These processes write to the metadata table, which can lead to slower shutdown times.
+* {% ghi 4868 %} {% ghi 4871 %} Fixed listscans so that it shows a scan session id for batch scans instead
+  of always showing zero.
+* {% ghi 4845 %} InstanceOperations.getActiveCompaction(String) did not handle the address of a
+  Compactor process being passed in the parameter. This has been fixed.
+* {% ghi 5445 %} The `cf` and `cq` options for the DeleteMany and Grep shell commands were not being
+  handled properly.
+
+### Metrics Improvements
+
+* {% ghi 4756 %} {% ghi 4757 %} {% ghi 4840 %} Added metric to indicate how many zombie scan threads are running
+  in the TabletServer. 
+* {% ghi 5011 %} Added queue tag to metrics emitted from the External Compactor processes.
+* {% ghi 5025 %} {% ghi 4922 %} Added property `general.micrometer.log.metrics` to enable metrics on
+  the log4j2 or logback logging frameworks. Disabled by default.
+
+### Other Improvements
+
+* {% ghi 4755 %} {% ghi 5220 %} Fixed the help flag for the admin command so that it works for subcommands.
+* {% ghi 4819 %} Tablets that are closing will no longer wait on scans to complete. Instead they
+  will try to interrupt the scan and then continue closing the tablet so that it can be migrated.
+  It's possible that a zombie scan thread could remain in the TabletServer, if the scan thread is
+  blocked on something and does not die. Users should monitor the new zombie scan metric mentioned
+  in the section above.
+* {% ghi 4867 %} Lowered the memory burden of listing a large number of External Compactors in the Monitor.
+* {% ghi 5026 %} Modified CompactionJobPrioritizer.createPriority to give a higher priority to tablets that
+  have more files than the maximum number of files per tablet.
+* {% ghi 5400 %} Modified AESCryptoService to prevent the creation of overlapping streams.
+
+## Requirements
+
+Accumulo 2.1.4 now requires JDK 17 to build, but still supports Java 11 runtime.
+
+## Upgrading
+
+View the [Upgrading Accumulo documentation][upgrade] for guidance.
+
+## Useful Links
+
+* [All Changes since 2.1.3][all-changes]
+* [All tickets related to this release][milestone]
+
+
+[upgrade]: /docs/2.x/administration/upgrading
+[milestone]: https://github.com/apache/accumulo/milestone/21
+[all-changes]: https://github.com/apache/accumulo/compare/rel/2.1.3...apache:rel/2.1.4