Roman Khachatryan created FLINK-27114:
-----------------------------------------
Summary: On JM restart, the information about the initial
checkpoints can be lost
Key: FLINK-27114
URL: https://issues.apache.org/jira/browse/FLINK-27114
Project: Flink
Issue Type: Bug
Components: Runtime / Checkpointing
Affects Versions: 1.14.4, 1.15.0, 1.16.0
Reporter: Roman Khachatryan
Fix For: 1.16.0, 1.14.5, 1.15.1
Scenario (1.14):
# A job starts from an existing checkpoint 1, with incremental checkpoints
enabled
# Checkpoint 1 is loaded with discardOnSubsume=false by
CheckpointCoordinator.restoreSavepoint
# A new checkpoint 2 completes, it reuses some state from the initial
checkpoint
# At some point, checkpoint 1 is subsumed, but the state is not discarded
(thanks to discardOnSubsume=false, ref counts stay 1)
# JM crashes
# JM restarts, loads the checkpoints 2..x from ZK (or other store) -
discardOnSubsume=true (as deserialized from handles)
# At some point, checkpoint 2 is subsumed and the initial shared state is not
used anymore; because checkpoint 2 has discardOnSubsume=true, shared state will
be erroneously discarded
In 1.15, there were the following changes:
# RestoreMode was added; only NO_CLAIM and LEGACY modes are affected
# SharedStateRegistry was changed from refCounts to highest checkpoint ID
# In step (7), state will not be discarded; however, because it's impossible
to distinguish initial state from the state created by this job, the latter
will not be discarded as well, leading to left-over state artifacts.
The proposed solution is to store the initial checkpoint ID (in store such as
ZK or in checkpoints) and adjust steps 6 or 7.
--
This message was sent by Atlassian Jira
(v8.20.1#820001)
