Shaun Sabo created SOLR-11815:
---------------------------------
Summary: TLOG leaders going down and rejoining as a replica do
fullCopy when not needed
Key: SOLR-11815
URL: https://issues.apache.org/jira/browse/SOLR-11815
Project: Solr
Issue Type: Bug
Security Level: Public (Default Security Level. Issues are Public)
Components: replication (java)
Affects Versions: 7.2
Environment: Oracle JDK 1.8
Ubuntu 16.04
Reporter: Shaun Sabo
I am running a collection with a persistent high volume of writes. When the
leader goes down and recovers, it joins as a replica and asks the new leader
for the files to Sync. The isIndexStale check is finding that some files differ
in size and checksum which forces a fullCopy. Since our indexes are rather
large, a rolling restart is resulting in large amounts of data transfer, and in
some cases disk space contention issues.
I do not believe the fullCopy is necessary given the circumstances.
Repro Steps:
1. collection/shard with 1 leader and 1 replica are accepting writes
- Pull interval is 30 seconds
- Hard Commit interval is 60 seconds
2. Replica executes an index pull and completes.
3. Leader process Hard Commits (replica index is delayed)
4. leader process is killed (SIGTERM)
5. Replica takes over as new leader
6. New leader applies TLOG since last pull (cores are binary-divergent now)
7. Former leader comes back as New Replica
8. New replica initiates recovery
- Recovery detects that the generation and version are behind and a check
is necessary
9. isIndexStale() detects that a segment exists on both the New Replica and New
Leader but that the size and checksum differ.
- This triggers fullCopy to be flagged on
10. Entirety of index is pulled regardless of changes
The majority of files should not have changes, but everything gets pulled
because of the first file it finds with a mismatched checksum.
Relevant Code:
https://github.com/apache/lucene-solr/blob/master/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java#L516-L518
https://github.com/apache/lucene-solr/blob/master/solr/core/src/java/org/apache/solr/handler/IndexFetcher.java#L1105-L1126
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
