[SPARK-23683][SQL] FileCommitProtocol.instantiate() hardening by steveloughran · Pull Request #20824 · apache/spark

steveloughran · 2018-03-14T18:20:16Z

What changes were proposed in this pull request?

With SPARK-20236, FileCommitProtocol.instantiate() looks for a three argument constructor, passing in the dynamicPartitionOverwrite parameter. If there is no such constructor, it falls back to the classic two-arg one.

When InsertIntoHadoopFsRelationCommand passes down that dynamicPartitionOverwrite flag to FileCommitProtocol.instantiate(), it assumes that the instantiated protocol supports the specific requirements of dynamic partition overwrite. It does not notice when this does not hold, and so the output generated may be incorrect.

This patch changes FileCommitProtocol.instantiate() so when dynamicPartitionOverwrite == true, it requires the protocol implementation to have a 3-arg constructor. Classic two arg constructors are supported when it is false.

Also it adds some debug level logging for anyone trying to understand what's going on.

How was this patch tested?

Unit tests verify that

classes with only 2-arg constructor cannot be used with dynamic overwrite
classes with only 2-arg constructor can be used without dynamic overwrite
classes with 3 arg constructors can be used with both.
the fallback to any two arg ctor takes place after the attempt to load the 3-arg ctor,
passing in invalid class types fail as expected (regression tests on expected behavior)

…argument constructor, passing in the dynamicPartitionOverwrite parameter. If there is no such constructor, it falls back to the classic two-arg one. When InsertIntoHadoopFsRelationCommand passes down that dynamicPartitionOverwrite flag to FileCommitProtocol.instantiate(), it assumes that the instantiated protocol supports the specific requirements of dynamic partition overwrite. It does not notice when this does not hold, and so the output generated may be incorrect. This patch changes FileCommitProtocol.instantiate() so when dynamicPartitionOverwrite == true, it requires the protocol implementation to have a 3-arg constructor. Tests verify that * classes with only 2-arg constructor cannot be used with dynamic overwrite * classes with only 2-arg constructor can be used without dynamic overwrite * classes with 3 arg constructors can be used with both * the fallback to any two arg ctor takes place after the attempt to load the 3-arg ctor, * passing in invalid class types fail as expected (regression tests on expected behavior) Change-Id: I694868aecf865cfa552e031ea3f6dde8b600fa7b

SparkQA · 2018-03-14T18:24:54Z

Test build #88236 has finished for PR 20824 at commit 529db08.

This patch fails Scala style tests.
This patch merges cleanly.
This patch adds no public classes.

cloud-fan · 2018-03-14T20:01:38Z

+ instantiateClassic(true)
+ }
+ // check the contents of the message and rethrow if unexpected
+ if (!ex.toString.contains("Dynamic Partition Overwrite")) {


in the test it's more conventional to write assert(ex.toString.contains("Dynamic Partition Overwrite"))

yes, but that loses the stack trace. And if there's one thing everyone hates is a jenkins build which says "you got the wrong exception but we won't say what", especially when you click through to the logs & see they've already been deleted.
This is why when I reimplemented intercept for java8 intercept/5
added the ability to specify a string which was contained
if the evaluated closure doesn't raise and exception, and doesn't return void or null, call toString() on the output (robustly) and include it in the message.
What I could do here is use fail(message, throwable) and make clear what the failure was? That way, the fact it's an assertion failure is visible, but the stack is retained?

How about leaving a small comment here in order to prevent that someone fixes it without noticing that? I would wonder why assert(ex.toString.contains(...)) is not used here too.

cloud-fan · 2018-03-14T20:05:43Z

LGTM, pending Jenkins, thanks!

…tion Change-Id: I92500e88d6fca40f7d7dfc7e073727c987b7c45c

SparkQA · 2018-03-15T02:05:55Z

Test build #88241 has finished for PR 20824 at commit a18ed58.

This patch fails PySpark unit tests.
This patch merges cleanly.
This patch adds no public classes.

HyukjinKwon · 2018-03-15T02:18:32Z

Hey @steveloughran, can you fix the title to like [SPARK-20236][SQL][FOLLOW-UP] ... BTW?

HyukjinKwon · 2018-03-15T02:38:08Z

Or .. should it be SPARK-23683? I just saw you opened a JIRA.

jiangxb1987

LGTM

steveloughran · 2018-03-15T10:32:53Z

Fixed the title, used the new JIRA.

…xception handling Change-Id: I9858d9fc625e64c3de75dc69c79b12fffdf79b06

SparkQA · 2018-03-15T13:52:50Z

Test build #88263 has finished for PR 20824 at commit 64602ae.

This patch fails Spark unit tests.
This patch merges cleanly.
This patch adds no public classes.

HyukjinKwon · 2018-03-15T14:28:05Z

+ logDebug("Falling back to (String, String) constructor")
+ require(!dynamicPartitionOverwrite,
+ "Dynamic Partition Overwrite is enabled but" +
+ s" the committer ${className} does not have the appropriate constructor")


BTW, why don't we warn and continue? Just wanted to make sure that we took this case into account. For example,
wouldn't this invalidate the case below?
privateclassCommitProtocol(arg1: String, arg2: String) extendsHadoopMapReduceCommitProtocol(arg1, arg2, true) { }

Problem is that the dynamic partition logic in InsertIntoHadoopFsRelationCommand assumes that rename() is a fast reliable operation you can do with any implementation of the FileCommitProtocol, sets itself up for it when enabled, then instantiates the inner committer, and carries on with the dynamic partitioning, irrespective of whether or not. rename() doesn't always work like that, breaking the rest of the algorithm.
If the committer doesn't have that 3-arg constructor, you can't be confident that you can do that. To silently log and continue is to run the risk that the underlying committers commit algorithm isn't compatible with the algorithm.
A fail-fast ensures that when the outcome is going to be unknown, you aren' t left trying to work out what's happened.
Regarding your example, yes, it's in trouble. Problem is: how to differentiate that from subclasses which don't know anything at all about the new feature. you can't even look for an interface on the newly created object if the base class implements it; you are left with some dynamic probe of the instance.

Hm .. actually we could do .. for example ..
abstractclassFileCommitProtocol { ... defdynamicPartitionOverwrite:Boolean=false }
classHadoopMapReduceCommitProtocol( jobId: String, path: String, overridevaldynamicPartitionOverwrite:Boolean=false)
(^ it's not double checked closely, for example, if the signature is safe or not. Was just an idea)
and use committer.dynamicPartitionOverwrite in InsertIntoHadoopFsRelationCommand to respect if the commit protocol supports or not, if I understood all correctly, and then produce a warning (or throw an error?) saying dynamic partition overwrite will be ignored (or not).
However, sure. I think this case is kind of a made-up case and should be a corner case I guess. I don't want to suggest an overkill (maybe) and I think we don't have to make this complicated too much for now.
I am okay as is. Just wanted to make sure that we considered and checked other possible stories.

something like that would work, though it'd be bit more convoluted...InsertIntoFSRelation would have to check, and then handle the situation of missing support.
One thing to consider in any form is: all implementations of FileCommitProtocol should be aware of the new Dynamic Partition overwrite feature...adding a new 3-arg constructor is an implicit way of saying "I understand this". Where it's weak is there's no way for for it to say "I understand this and will handle it myself" Because essentially that's what being done in the [Netflix Partioned committer(https://github.com/apache/hadoop/blob/trunk/hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/commit/staging/PartitionedStagingCommitter.java#L142), which purges all parts for which the new job has data. With that committer, if the insert asks for the feature then the FileCommitProtocol binding to it could (somehow) turn this on and so handle everything internally.
Like I said, a more complex model. It'd need changes a fair way through things and then the usual complexity of getting commit logic.

HyukjinKwon · 2018-03-15T14:48:51Z

retest this please

SparkQA · 2018-03-15T18:48:26Z

Test build #88267 has finished for PR 20824 at commit 64602ae.

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

HyukjinKwon · 2018-03-16T03:19:37Z

Not a big deal at all but I acutally meant [SPARK-20236][SQL][FOLLOW-UP] ... or [SPARK-23683][SQL] ... for title .. I am sorry that I wasn't clear.

cloud-fan · 2018-03-16T22:41:23Z

thanks, merging to master!

## What changes were proposed in this pull request? With SPARK-20236, `FileCommitProtocol.instantiate()` looks for a three argument constructor, passing in the `dynamicPartitionOverwrite` parameter. If there is no such constructor, it falls back to the classic two-arg one. When `InsertIntoHadoopFsRelationCommand` passes down that `dynamicPartitionOverwrite` flag `to FileCommitProtocol.instantiate(`), it assumes that the instantiated protocol supports the specific requirements of dynamic partition overwrite. It does not notice when this does not hold, and so the output generated may be incorrect. This patch changes `FileCommitProtocol.instantiate()` so when `dynamicPartitionOverwrite == true`, it requires the protocol implementation to have a 3-arg constructor. Classic two arg constructors are supported when it is false. Also it adds some debug level logging for anyone trying to understand what's going on. ## How was this patch tested? Unit tests verify that * classes with only 2-arg constructor cannot be used with dynamic overwrite * classes with only 2-arg constructor can be used without dynamic overwrite * classes with 3 arg constructors can be used with both. * the fallback to any two arg ctor takes place after the attempt to load the 3-arg ctor, * passing in invalid class types fail as expected (regression tests on expected behavior) Author: Steve Loughran <stevel@hortonworks.com> Closesapache#20824 from steveloughran/stevel/SPARK-23683-protocol-instantiate.

cloud-fan reviewed Mar 14, 2018
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SPARK-20236: fix style typo and improve failure reporting on an asser…
a18ed58
…tion Change-Id: I92500e88d6fca40f7d7dfc7e073727c987b7c45c

jiangxb1987 approved these changes Mar 15, 2018
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steveloughran changed the title ~~With SPARK-20236, FileCommitProtocol.instantiate() looks for a three …~~[SPARK-20236][SQL][FOLLOW-UP] FileCommitProtocol.instantiate() hardeningMar 15, 2018

steveloughran changed the title ~~[SPARK-20236][SQL][FOLLOW-UP] FileCommitProtocol.instantiate() hardening~~[SPARK-23683][SQL][FOLLOW-UP] FileCommitProtocol.instantiate() hardeningMar 15, 2018

SPARK-23683 document why the test is not using assert() to validate e…
64602ae
…xception handling Change-Id: I9858d9fc625e64c3de75dc69c79b12fffdf79b06

HyukjinKwon reviewed Mar 15, 2018
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HyukjinKwon approved these changes Mar 16, 2018
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steveloughran changed the title ~~[SPARK-23683][SQL][FOLLOW-UP] FileCommitProtocol.instantiate() hardening~~[SPARK-23683][SQL] FileCommitProtocol.instantiate() hardeningMar 16, 2018

asfgit closed this in 8a1efe3Mar 16, 2018

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