Burak Yavuz created SPARK-20230:
-----------------------------------
Summary: FetchFailedExceptions should invalidate file caches in
MapOutputTracker even if newer stages are launched
Key: SPARK-20230
URL: https://issues.apache.org/jira/browse/SPARK-20230
Project: Spark
Issue Type: Bug
Components: Spark Core
Affects Versions: 2.1.0
Reporter: Burak Yavuz
If you lose instances that have shuffle outputs, you will start observing
messages like:
{code}
17/03/24 11:49:23 WARN TaskSetManager: Lost task 0.0 in stage 64.1 (TID 3849,
172.128.196.240, executor 0): FetchFailed(BlockManagerId(4, 172.128.200.157,
4048, None), shuffleId=16, mapId=2, reduceId=3, message=
{code}
Generally, these messages are followed by:
{code}
17/03/24 11:49:23 INFO DAGScheduler: Executor lost: 4 (epoch 20)
17/03/24 11:49:23 INFO BlockManagerMasterEndpoint: Trying to remove executor 4
from BlockManagerMaster.
17/03/24 11:49:23 INFO BlockManagerMaster: Removed 4 successfully in
removeExecutor
17/03/24 11:49:23 INFO DAGScheduler: Shuffle files lost for executor: 4 (epoch
20)
17/03/24 11:49:23 INFO ShuffleMapStage: ShuffleMapStage 63 is now unavailable
on executor 4 (73/89, false)
{code}
which is great. Spark resubmits tasks for data that has been lost. However, if
you have cascading instance failures, then you may come across:
{code}
17/03/24 11:48:39 INFO DAGScheduler: Ignoring fetch failure from ResultTask(64,
46) as it's from ResultStage 64 attempt 0 and there is a more recent attempt
for that stage (attempt ID 1) running
{code}
which don't invalidate file outputs. In later retries of the stage, Spark will
attempt to access files on machines that don't exist anymore, and then after 4
tries, Spark will give up. If it had not ignored the fetch failure, and
invalidated the cache, then most of the lost files could have been computed
during one of the previous retries.
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