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[SPARK-17624][SQL][STREAMING][TEST] Fixed flaky StateStoreSuite.maintenance #15592

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@tdas tdas commented Oct 21, 2016

What changes were proposed in this pull request?

The reason for the flakiness was follows. The test starts the maintenance background thread, and then writes 20 versions of the state store. The maintenance thread is expected to create snapshots in the middle, and clean up old files that are not needed any more. The earliest delta file (1.delta) is expected to be deleted as snapshots will ensure that the earliest delta would not be needed.

However, the default configuration for the maintenance thread is to retain files such that last 2 versions can be recovered, and delete the rest. Now while generating the versions, the maintenance thread can kick in and create snapshots anywhere between version 10 and 20 (at least 10 deltas needed for snapshot). Then later it will choose to retain only version 20 and 19 (last 2). There are two cases.

  • Common case: One of the version between 10 and 19 gets snapshotted. Then recovering versions 19 and 20 just needs 19.snapshot and 20.delta, so 1.delta gets deleted.
  • Uncommon case (reason for flakiness): Only version 20 gets snapshotted. Then recovering versoin 20 requires 20.snapshot, and recovering version 19 all the previous 19...1.delta. So 1.delta does not get deleted.

This PR rearranges the checks such that it create 20 versions, and then waits that there is at least one snapshot, then creates another 20. This will ensure that the latest 2 versions cannot require anything older than the first snapshot generated, and therefore will 1.delta will be deleted.

In addition, I have added more logs, and comments that I felt would help future debugging and understanding what is going on.

How was this patch tested?

Ran the StateStoreSuite > 6K times in a heavily loaded machine (10 instances of tests running in parallel). No failures.

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tdas commented Oct 21, 2016

@zsxwing Can you take a look?

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SparkQA commented Oct 22, 2016

Test build #67361 has finished for PR 15592 at commit 96079fe.

  • This patch passes all tests.
  • This patch merges cleanly.
  • This patch adds no public classes.

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zsxwing commented Oct 25, 2016

LGTM. Thanks! Merging to master and 2.0.

@asfgit asfgit closed this in 407c3ce Oct 25, 2016
asfgit pushed a commit that referenced this pull request Oct 25, 2016
…enance

## What changes were proposed in this pull request?

The reason for the flakiness was follows. The test starts the maintenance background thread, and then writes 20 versions of the state store. The maintenance thread is expected to create snapshots in the middle, and clean up old files that are not needed any more. The earliest delta file (1.delta) is expected to be deleted as snapshots will ensure that the earliest delta would not be needed.

However, the default configuration for the maintenance thread is to retain files such that last 2 versions can be recovered, and delete the rest. Now while generating the versions, the maintenance thread can kick in and create snapshots anywhere between version 10 and 20 (at least 10 deltas needed for snapshot). Then later it will choose to retain only version 20 and 19 (last 2). There are two cases.

- Common case: One of the version between 10 and 19 gets snapshotted. Then recovering versions 19 and 20 just needs 19.snapshot and 20.delta, so 1.delta gets deleted.

- Uncommon case (reason for flakiness): Only version 20 gets snapshotted. Then recovering versoin 20 requires 20.snapshot, and recovering version 19 all the previous 19...1.delta. So 1.delta does not get deleted.

This PR rearranges the checks such that it create 20 versions, and then waits that there is at least one snapshot, then creates another 20. This will ensure that the latest 2 versions cannot require anything older than the first snapshot generated, and therefore will 1.delta will be deleted.

In addition, I have added more logs, and comments that I felt would help future debugging and understanding what is going on.

## How was this patch tested?

Ran the StateStoreSuite > 6K times in a heavily loaded machine (10 instances of tests running in parallel). No failures.

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #15592 from tdas/SPARK-17624.

(cherry picked from commit 407c3ce)
Signed-off-by: Shixiong Zhu <shixiong@databricks.com>
robert3005 pushed a commit to palantir/spark that referenced this pull request Nov 1, 2016
…enance

## What changes were proposed in this pull request?

The reason for the flakiness was follows. The test starts the maintenance background thread, and then writes 20 versions of the state store. The maintenance thread is expected to create snapshots in the middle, and clean up old files that are not needed any more. The earliest delta file (1.delta) is expected to be deleted as snapshots will ensure that the earliest delta would not be needed.

However, the default configuration for the maintenance thread is to retain files such that last 2 versions can be recovered, and delete the rest. Now while generating the versions, the maintenance thread can kick in and create snapshots anywhere between version 10 and 20 (at least 10 deltas needed for snapshot). Then later it will choose to retain only version 20 and 19 (last 2). There are two cases.

- Common case: One of the version between 10 and 19 gets snapshotted. Then recovering versions 19 and 20 just needs 19.snapshot and 20.delta, so 1.delta gets deleted.

- Uncommon case (reason for flakiness): Only version 20 gets snapshotted. Then recovering versoin 20 requires 20.snapshot, and recovering version 19 all the previous 19...1.delta. So 1.delta does not get deleted.

This PR rearranges the checks such that it create 20 versions, and then waits that there is at least one snapshot, then creates another 20. This will ensure that the latest 2 versions cannot require anything older than the first snapshot generated, and therefore will 1.delta will be deleted.

In addition, I have added more logs, and comments that I felt would help future debugging and understanding what is going on.

## How was this patch tested?

Ran the StateStoreSuite > 6K times in a heavily loaded machine (10 instances of tests running in parallel). No failures.

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes apache#15592 from tdas/SPARK-17624.
uzadude pushed a commit to uzadude/spark that referenced this pull request Jan 27, 2017
…enance

## What changes were proposed in this pull request?

The reason for the flakiness was follows. The test starts the maintenance background thread, and then writes 20 versions of the state store. The maintenance thread is expected to create snapshots in the middle, and clean up old files that are not needed any more. The earliest delta file (1.delta) is expected to be deleted as snapshots will ensure that the earliest delta would not be needed.

However, the default configuration for the maintenance thread is to retain files such that last 2 versions can be recovered, and delete the rest. Now while generating the versions, the maintenance thread can kick in and create snapshots anywhere between version 10 and 20 (at least 10 deltas needed for snapshot). Then later it will choose to retain only version 20 and 19 (last 2). There are two cases.

- Common case: One of the version between 10 and 19 gets snapshotted. Then recovering versions 19 and 20 just needs 19.snapshot and 20.delta, so 1.delta gets deleted.

- Uncommon case (reason for flakiness): Only version 20 gets snapshotted. Then recovering versoin 20 requires 20.snapshot, and recovering version 19 all the previous 19...1.delta. So 1.delta does not get deleted.

This PR rearranges the checks such that it create 20 versions, and then waits that there is at least one snapshot, then creates another 20. This will ensure that the latest 2 versions cannot require anything older than the first snapshot generated, and therefore will 1.delta will be deleted.

In addition, I have added more logs, and comments that I felt would help future debugging and understanding what is going on.

## How was this patch tested?

Ran the StateStoreSuite > 6K times in a heavily loaded machine (10 instances of tests running in parallel). No failures.

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes apache#15592 from tdas/SPARK-17624.
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