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Posted to issues@flink.apache.org by StephanEwen <gi...@git.apache.org> on 2018/03/06 11:55:27 UTC
[GitHub] flink pull request #5645: FLINK-8876 Improve concurrent access handling in s...
GitHub user StephanEwen opened a pull request:
https://github.com/apache/flink/pull/5645
FLINK-8876 Improve concurrent access handling in stateful serializers
## What is the purpose of the change
Help detecting accidental concurrent use of serializers.
If the log is set to `DEBUG`, or assertions are enabled (as they are during tests), the serializers will remember the current thread that performs serialization/deserialization/copying and throw an error if another thread accesses the serializer at the same time.
The code that implements that check is under a `static final` flag, so should be eliminated by the JIT if the utility is not active, meaning it has zero cost when not used. To initialize the flag, we use the logger (using the fact that Java initializes static fields in order) and a utility class (using the fact that the utility class is initialized before the serializer class.)
## Brief change log
- Add a concurrency detector to the KryoSerializer
- Add a concurrency detector to the AvroSerializer
## Verifying this change
The change adds unit tests to validate the effectiveness of the utility.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (yes / **no)**
- The public API, i.e., is any changed class annotated with `@Public(Evolving)`: (yes / **no)**
- The serializers: **(yes** / no / don't know)
- The runtime per-record code paths (performance sensitive): **(yes** / no / don't know)
- Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (yes / **no** / don't know)
- The S3 file system connector: (yes / **no** / don't know)
## Documentation
- Does this pull request introduce a new feature? **(yes** / no)
- If yes, how is the feature documented? (**not applicable** / docs / JavaDocs / not documented)
There is no change that users should make, this simply enhances test coverage and results in more meaningful errors during debug runs.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/StephanEwen/incubator-flink kryo_safety
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/5645.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #5645
----
commit 4a99516ca938bf4cf6dfcdbd0e5e4615367c8eac
Author: Stephan Ewen <se...@...>
Date: 2018-03-04T11:11:29Z
[FLINK-8877] [core] Set Kryo trace if Flink log level is TRACE
commit 3f20d2098de39997b89b79366a636c4dde77dc6a
Author: Stephan Ewen <se...@...>
Date: 2018-03-06T10:30:54Z
[FLINK-8878] [tests] Add BlockerSync utility
This helps to synchronize two threads of which one is expected to block
while holding a resource.
commit 727003165447ee2a925b3030f19afe4e1b3b5325
Author: Stephan Ewen <se...@...>
Date: 2018-03-04T11:20:17Z
[FLINK-8878] [core] Add concurrency check Kryo Serializer on DEBUG level
commit 714ee8882f86aa2a969dc842097dc11687d04607
Author: Stephan Ewen <se...@...>
Date: 2018-03-06T10:21:08Z
[FLINK-8879] [avro] Add concurrency check Avro Serializer on DEBUG level.
----
---
[GitHub] flink issue #5645: FLINK-8876 Improve concurrent access handling in stateful...
Posted by zentol <gi...@git.apache.org>.
Github user zentol commented on the issue:
https://github.com/apache/flink/pull/5645
The end-to-end test would be cheap as we wouldn't execute a flink job or even start a flink cluster.
The scripts in `flink-end-to-end-tests` can do pretty much anything they want; my idea was to just call the test method in a non-test context, in which case the test should throw an AssertionError. It may not be the cleanest thing to do though as we have to max test and production code in a single jar.
My goal was to verify that the sections guarded by `CONCURRENT_ACCESS_CHECK` are skipped at runtime by default. As it stands someone could just hard-code it to `true` and there's no test preventing that.
---
[GitHub] flink issue #5645: FLINK-8876 Improve concurrent access handling in stateful...
Posted by zentol <gi...@git.apache.org>.
Github user zentol commented on the issue:
https://github.com/apache/flink/pull/5645
We got a bunch of failing tests:
```
Failed tests:
MultidimensionalArraySerializerTest.testObjectArrays:84 Exception in test: Serializer already accessed by thread main
PojoGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testBeanStyleObjects:95->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
PojoGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testCompositeObject:75->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
PojoGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testNestedInterfaces:124->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
PojoGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testNestedObjects:85->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
PojoGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testSimpleTypesObjects:64->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
PojoSubclassSerializerTest>SerializerTestBase.testSerializedCopyAsSequence:402 Exception in test: Serializer already accessed by thread main
PojoSubclassSerializerTest>SerializerTestBase.testSerializedCopyIndividually:364 Exception in test: Serializer already accessed by thread main
SubclassFromInterfaceSerializerTest>SerializerTestBase.testSerializedCopyAsSequence:402 Exception in test: Serializer already accessed by thread main
SubclassFromInterfaceSerializerTest>SerializerTestBase.testSerializedCopyIndividually:364 Exception in test: Serializer already accessed by thread main
TupleSerializerTest.testTuple5CustomObjects:215->runTests:229 Exception in test: Serializer already accessed by thread main
KryoGenericArraySerializerTest>AbstractGenericArraySerializerTest.testBeanStyleObjects:120->AbstractGenericArraySerializerTest.runTests:152->AbstractGenericArraySerializerTest.runTests:173 Exception in test: Serializer already accessed by thread main
KryoGenericArraySerializerTest>AbstractGenericArraySerializerTest.testCompositeObject:93->AbstractGenericArraySerializerTest.runTests:152->AbstractGenericArraySerializerTest.runTests:173 Exception in test: Serializer already accessed by thread main
KryoGenericArraySerializerTest>AbstractGenericArraySerializerTest.testNestedObjects:103->AbstractGenericArraySerializerTest.runTests:152->AbstractGenericArraySerializerTest.runTests:173 Exception in test: Serializer already accessed by thread main
KryoGenericArraySerializerTest>AbstractGenericArraySerializerTest.testSimpleTypesObjects:82->AbstractGenericArraySerializerTest.runTests:152->AbstractGenericArraySerializerTest.runTests:173 Exception in test: Serializer already accessed by thread main
KryoGenericArraySerializerTest>AbstractGenericArraySerializerTest.testString:63->AbstractGenericArraySerializerTest.runTests:152->AbstractGenericArraySerializerTest.runTests:173 Exception in test: Serializer already accessed by thread main
KryoGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testBeanStyleObjects:95->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testCompositeObject:75->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoGenericTypeSerializerTest.testJavaDequeue:68->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoGenericTypeSerializerTest.testJavaList:50->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoGenericTypeSerializerTest.testJavaSet:59->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testNestedInterfaces:124->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testNestedObjects:85->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testSimpleTypesObjects:64->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testString:41->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoSerializerClassLoadingTest>SerializerTestBase.testSerializedCopyAsSequence:402 Exception in test: Serializer already accessed by thread main
KryoSerializerClassLoadingTest>SerializerTestBase.testSerializedCopyIndividually:364 Exception in test: Serializer already accessed by thread main
KryoWithCustomSerializersTest>AbstractGenericTypeSerializerTest.testBeanStyleObjects:95->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoWithCustomSerializersTest>AbstractGenericTypeSerializerTest.testCompositeObject:75->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoWithCustomSerializersTest.testJodaTime:48->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoWithCustomSerializersTest>AbstractGenericTypeSerializerTest.testNestedInterfaces:124->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoWithCustomSerializersTest>AbstractGenericTypeSerializerTest.testNestedObjects:85->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoWithCustomSerializersTest>AbstractGenericTypeSerializerTest.testSimpleTypesObjects:64->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
KryoWithCustomSerializersTest>AbstractGenericTypeSerializerTest.testString:41->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
```
```
Failed tests:
AvroGenericArraySerializerTest>AbstractGenericArraySerializerTest.testBeanStyleObjects:120->AbstractGenericArraySerializerTest.runTests:152->AbstractGenericArraySerializerTest.runTests:173 Exception in test: Serializer already accessed by thread main
AvroGenericArraySerializerTest>AbstractGenericArraySerializerTest.testCompositeObject:93->AbstractGenericArraySerializerTest.runTests:152->AbstractGenericArraySerializerTest.runTests:173 Exception in test: Serializer already accessed by thread main
AvroGenericArraySerializerTest>AbstractGenericArraySerializerTest.testNestedObjects:103->AbstractGenericArraySerializerTest.runTests:152->AbstractGenericArraySerializerTest.runTests:173 Exception in test: Serializer already accessed by thread main
AvroGenericArraySerializerTest>AbstractGenericArraySerializerTest.testSimpleTypesObjects:82->AbstractGenericArraySerializerTest.runTests:152->AbstractGenericArraySerializerTest.runTests:173 Exception in test: Serializer already accessed by thread main
AvroGenericArraySerializerTest>AbstractGenericArraySerializerTest.testString:63->AbstractGenericArraySerializerTest.runTests:152->AbstractGenericArraySerializerTest.runTests:173 Exception in test: Serializer already accessed by thread main
AvroGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testBeanStyleObjects:95->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
AvroGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testCompositeObject:75->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
AvroGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testNestedInterfaces:124->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
AvroGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testNestedObjects:85->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
AvroGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testSimpleTypesObjects:64->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
AvroGenericTypeSerializerTest>AbstractGenericTypeSerializerTest.testString:41->AbstractGenericTypeSerializerTest.runTests:155 Exception in test: Serializer already accessed by thread main
AvroSerializerEmptyArrayTest.testBookSerialization:42 Exception in test: Serializer already accessed by thread main
AvroSerializerEmptyArrayTest.testSerialization:67 Exception in test: Serializer already accessed by thread main
AvroSerializerTest>SerializerTestBase.testSerializedCopyAsSequence:402 Exception in test: Serializer already accessed by thread main
AvroSerializerTest>SerializerTestBase.testSerializedCopyIndividually:364 Exception in test: Serializer already accessed by thread main
```
The changes itself look(ed) good to me, but we'll have to check whether the tests do something wrong or the code in the PR uses wrong assumptions.
I've verified manually that the `CONCURRENT_ACCESS_CHECK` setup works properly outside of tests. I'm wondering whether we can test this as well in `flink-end-to-end-tests`.
---
[GitHub] flink issue #5645: FLINK-8876 Improve concurrent access handling in stateful...
Posted by StephanEwen <gi...@git.apache.org>.
Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/5645
Thanks for the great review.
Good catch, I bet the missing check against the current thread is the reason for the test failure.
---
[GitHub] flink pull request #5645: FLINK-8876 Improve concurrent access handling in s...
Posted by zentol <gi...@git.apache.org>.
Github user zentol commented on a diff in the pull request:
https://github.com/apache/flink/pull/5645#discussion_r172509993
--- Diff: flink-core/src/main/java/org/apache/flink/api/java/typeutils/runtime/kryo/KryoSerializer.java ---
@@ -502,6 +572,22 @@ private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundE
// For testing
// --------------------------------------------------------------------------------------------
+ private void enterExclusiveThread() {
+ // we use simple get, check, set here, rather than CAS
+ // we don't need lock-style correctness, this is only a sanity-check and we thus
+ // favor speed at the cost of some false negatives in this check
+ Thread previous = currentThread;
+ if (previous == null) {
+ currentThread = Thread.currentThread();
+ } else {
+ throw new IllegalStateException("Serializer already accessed by thread " + previous.getName());
--- End diff --
you also have to check for equality between previous and Thread.currentThread, as copy() also calls serialize/deserialize().
---
[GitHub] flink pull request #5645: FLINK-8876 Improve concurrent access handling in s...
Posted by zentol <gi...@git.apache.org>.
Github user zentol commented on a diff in the pull request:
https://github.com/apache/flink/pull/5645#discussion_r172893030
--- Diff: flink-formats/flink-avro/src/main/java/org/apache/flink/formats/avro/typeutils/AvroSerializer.java ---
@@ -163,8 +224,19 @@ public T copy(T from, T reuse) {
@Override
public void copy(DataInputView source, DataOutputView target) throws IOException {
- T value = deserialize(source);
- serialize(value, target);
+ if (CONCURRENT_ACCESS_CHECK) {
+ enterExclusiveThread();
+ }
+
+ try {
+ T value = deserialize(source);
--- End diff --
Have to point out that after `deserialize()` the checks in copy() are ineffective as the `currentThread` field has already been nulled. In other words, we guard against concurrent access before deserialize(), and within deserialize()&serialize(), but not between deserialize()&serialize() or after serialize().
This isn't a _problem_ as all code is actually covered, but we may want to document that.
---
[GitHub] flink pull request #5645: FLINK-8876 Improve concurrent access handling in s...
Posted by zentol <gi...@git.apache.org>.
Github user zentol commented on a diff in the pull request:
https://github.com/apache/flink/pull/5645#discussion_r172510349
--- Diff: flink-formats/flink-avro/src/main/java/org/apache/flink/formats/avro/typeutils/AvroSerializer.java ---
@@ -277,6 +349,26 @@ private void initializeAvro() {
this.decoder = new DataInputDecoder();
}
+ // --------------------------------------------------------------------------------------------
+ // Concurrency checks
+ // --------------------------------------------------------------------------------------------
+
+ private void enterExclusiveThread() {
+ // we use simple get, check, set here, rather than CAS
+ // we don't need lock-style correctness, this is only a sanity-check and we thus
+ // favor speed at the cost of some false negatives in this check
+ Thread previous = currentThread;
+ if (previous == null) {
+ currentThread = Thread.currentThread();
+ } else {
--- End diff --
same as for kroy
---
[GitHub] flink issue #5645: FLINK-8876 Improve concurrent access handling in stateful...
Posted by StephanEwen <gi...@git.apache.org>.
Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/5645
I added a way to reset the flag into its original state (prior to assertion activation) and used that to test that the concurrency check is not active by default. The `KryoSerializerConcurrencyTest` tests the default test setting (concurrency checks on), the `KryoSerializerConcurrencyCheckInactiveITCase` tests the general default (concurrency checks off).
---
[GitHub] flink issue #5645: FLINK-8876 Improve concurrent access handling in stateful...
Posted by StephanEwen <gi...@git.apache.org>.
Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/5645
Ah, I see. Let me think whether there is an easy way to do that...
---
[GitHub] flink pull request #5645: FLINK-8876 Improve concurrent access handling in s...
Posted by StephanEwen <gi...@git.apache.org>.
Github user StephanEwen closed the pull request at:
https://github.com/apache/flink/pull/5645
---
[GitHub] flink issue #5645: FLINK-8876 Improve concurrent access handling in stateful...
Posted by StephanEwen <gi...@git.apache.org>.
Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/5645
Manually merged
---
[GitHub] flink pull request #5645: FLINK-8876 Improve concurrent access handling in s...
Posted by StephanEwen <gi...@git.apache.org>.
Github user StephanEwen commented on a diff in the pull request:
https://github.com/apache/flink/pull/5645#discussion_r172911926
--- Diff: flink-formats/flink-avro/src/main/java/org/apache/flink/formats/avro/typeutils/AvroSerializer.java ---
@@ -163,8 +224,19 @@ public T copy(T from, T reuse) {
@Override
public void copy(DataInputView source, DataOutputView target) throws IOException {
- T value = deserialize(source);
- serialize(value, target);
+ if (CONCURRENT_ACCESS_CHECK) {
+ enterExclusiveThread();
+ }
+
+ try {
+ T value = deserialize(source);
--- End diff --
An alternative would be to do the following, but I would honestly not do that. This is a heuristic anyways (otherwise we would need to use CAS on the `currentThread` field).
```java
private void enterExclusiveThread() {
Thread previous = currentThread;
Thread thisThread = Thread.currentThread();
if (previous == null) {
reEntranceDepth = 1;
currentThread = thisThread;
}
else if (previous == thisThread) {
reEntranceDepth++;
}
else {
throw new IllegalStateException(
"Concurrent access to KryoSerializer. Thread 1: " + thisThread.getName() +
" , Thread 2: " + previous.getName());
}
}
private void exitExclusiveThread() {
if (--reEntranceDepth == 0) {
currentThread = null;
}
}
```
---
[GitHub] flink issue #5645: FLINK-8876 Improve concurrent access handling in stateful...
Posted by StephanEwen <gi...@git.apache.org>.
Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/5645
Making the concurrent access check re-entrant fixes all tests.
My feeling would be to not add an end-to-end test for this, because end-to-end tests are quite expensive. Is this mainly for validating that this works by configuring the log level in your opinion?
---
[GitHub] flink pull request #5645: FLINK-8876 Improve concurrent access handling in s...
Posted by zentol <gi...@git.apache.org>.
Github user zentol commented on a diff in the pull request:
https://github.com/apache/flink/pull/5645#discussion_r172508524
--- Diff: flink-core/src/main/java/org/apache/flink/api/java/typeutils/runtime/kryo/KryoSerializer.java ---
@@ -502,6 +572,22 @@ private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundE
// For testing
// --------------------------------------------------------------------------------------------
+ private void enterExclusiveThread() {
+ // we use simple get, check, set here, rather than CAS
+ // we don't need lock-style correctness, this is only a sanity-check and we thus
+ // favor speed at the cost of some false negatives in this check
+ Thread previous = currentThread;
+ if (previous == null) {
+ currentThread = Thread.currentThread();
+ } else {
+ throw new IllegalStateException("Serializer already accessed by thread " + previous.getName());
--- End diff --
We can also print the current thread for debugging purposes.
---
[GitHub] flink pull request #5645: FLINK-8876 Improve concurrent access handling in s...
Posted by StephanEwen <gi...@git.apache.org>.
Github user StephanEwen commented on a diff in the pull request:
https://github.com/apache/flink/pull/5645#discussion_r172939401
--- Diff: flink-formats/flink-avro/src/main/java/org/apache/flink/formats/avro/typeutils/AvroSerializer.java ---
@@ -163,8 +224,9 @@ public T copy(T from, T reuse) {
@Override
public void copy(DataInputView source, DataOutputView target) throws IOException {
- T value = deserialize(source);
- serialize(value, target);
+ // we do not have concurrency checks here, because serialize() and
+ // deserialize() do the checks and the current mechanism does not handle
--- End diff --
oh, right, fixing...
---
[GitHub] flink issue #5645: FLINK-8876 Improve concurrent access handling in stateful...
Posted by StephanEwen <gi...@git.apache.org>.
Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/5645
@zentol Have a look at the way I solved that above, see if you agree that we covered our bases now.
---
[GitHub] flink pull request #5645: FLINK-8876 Improve concurrent access handling in s...
Posted by zentol <gi...@git.apache.org>.
Github user zentol commented on a diff in the pull request:
https://github.com/apache/flink/pull/5645#discussion_r172922843
--- Diff: flink-formats/flink-avro/src/main/java/org/apache/flink/formats/avro/typeutils/AvroSerializer.java ---
@@ -163,8 +224,9 @@ public T copy(T from, T reuse) {
@Override
public void copy(DataInputView source, DataOutputView target) throws IOException {
- T value = deserialize(source);
- serialize(value, target);
+ // we do not have concurrency checks here, because serialize() and
+ // deserialize() do the checks and the current mechanism does not handle
--- End diff --
looks like the end of the comment is missing
---
[GitHub] flink issue #5645: FLINK-8876 Improve concurrent access handling in stateful...
Posted by StephanEwen <gi...@git.apache.org>.
Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/5645
Merging this after fixing the comment...
---
[GitHub] flink pull request #5645: FLINK-8876 Improve concurrent access handling in s...
Posted by StephanEwen <gi...@git.apache.org>.
Github user StephanEwen commented on a diff in the pull request:
https://github.com/apache/flink/pull/5645#discussion_r172907369
--- Diff: flink-formats/flink-avro/src/main/java/org/apache/flink/formats/avro/typeutils/AvroSerializer.java ---
@@ -163,8 +224,19 @@ public T copy(T from, T reuse) {
@Override
public void copy(DataInputView source, DataOutputView target) throws IOException {
- T value = deserialize(source);
- serialize(value, target);
+ if (CONCURRENT_ACCESS_CHECK) {
+ enterExclusiveThread();
+ }
+
+ try {
+ T value = deserialize(source);
--- End diff --
I think we can simply remove the check around the `copy(DataInputView source, DataOutputView target)` because the respective critical parts (`serialize()` and `deserialize()`) are covered already.
---