[Performance] Use a faster serialization protocol within security plugin

[parasjain1]

Problem

JDK serialisation used by security plugin to serialize and deserialize various headers is slow.

Proposal

This is a proposal to change the implementation of Base64Helper::serializeObject and Base64Helper::deserializeObject to use a faster serialization protocol. I explored Fast Serialization, Protostuff, Kryo, Avro, and OpenSearch's Custom Serialization as alternatives to JDK serialization and ran a few benchmarks. Results are attached below.

Benchmarking Environment
Framework used - JMH, 1000 warm-up iterations, 30000 test iterations
EC2 InstanceType - c5.2xlarge
JDK - Corretto JDK 11
OS - Amazon Linux 2 x86_64

Type	User	User	User	InetSocketAddress	InetSocketAddress	InetSocketAddress	SourceFieldContext	SourceFieldContext	SourceFieldContext	User	User	User	InetSocketAddress	InetSocketAddress	InetSocketAddress	SourceFieldContext	SourceFieldContext	SourceFieldContext
Operation	deserialize	deserialize	deserialize	deserialize	deserialize	deserialize	deserialize	deserialize	deserialize	serialize	serialize	serialize	serialize	serialize	serialize	serialize	serialize	serialize
Stat	Avg Time (ns/op)	Error +/- ns/op	Diff %	Avg Time (ns/op)	Error +/- ns/op	Diff %	Avg Time (ns/op)	Error +/- ns/op	Diff %	Avg Time (ns/op)	Error +/- ns/op	Diff %	Avg Time (ns/op)	Error +/- ns/op	Diff %	Avg Time (ns/op)	Error +/- ns/op	Diff %
Java	26062.709	847.012		9732.072	309.654		7892.943	333.835		10370.249	319.919		4749.54	168.423		4023.138	146.527
FST	4299.802	251.09	-83.50209	3957.335	287.201	-59.33718	2168.463	66.373	-72.52656	3104.632	161.298	-70.06213	2578.204	115.172	-45.71676	1427.189	63.018	-64.52548
FST (Pre)	3674.455	133.466	-85.90148	3417.478	134.756	-64.88437	868.976	48.215	-88.99047	2899.691	131.584	-72.03837	2368.224	101.214	-50.13782	756.986	38.476	-81.18419
Proto	808.423	40.851	-96.89816				1003.155	29.785	-87.29048	1423.777	59.772	-86.27056				1138.412	70.829	-71.70338
Custom (OpenSearch)	834.74	56.749	-96.79719				834.987	30.013	-89.42109	1115.154	69.707	-89.2466				1123.486	37.035	-72.07439
Kryo (Pre)				1274.085	20.928	-86.90839							1544.436	55.018	-67.48241	55.018

• Though FST is highly performant, simplest to use amongst all, it comes with its own shortcomings. FST no longer seems to be actively maintained with last commit made 2yrs ago and 102 open issues, history of breaking changes even with minor version upgrades.
• Protostuff too is highly performant, but will need explicit handling for certain classes such as InetSocketAddress by writing Delegates. Protostuff too doesn't seem to be actively maintained, last commit was 1yr ago.
• Kryo does not work out of the box. Kryo does not work with classes with no zero-arg constructors. We'll have to write serializers. Discovered that for complex objects for eg. java.util.Collections$SynchronizedMap we'll have to register separate serializers. There's a repo kryo-serializers that has many such serializers that we can use. Given we already have highly optimised custom serialization framework (StreamOutput, StreamInput) within OpenSearch, expending effort to integrate with another library seems unnecessary.
• Custom serialization using OpenSearch's BytesStreamOutput and BytesStreamInput classes is a promising approach. It too is highly performant. For the classes that are defined within security plugin such as User, SourceFieldsContext - Writeable interface can be implemented. For classes such as InetSocketAddress which we cannot change, we'll have to add Writers and Read methods to the StreamOutput and StreamInput classes to be able to use writeGenericObject and readGenericObject methods. This is inline with how OpenSearch deals with third party classes today. [source code]

To conclude, we propose to use custom serialization for headers in security plugin.

Solution

This change is to proposed to be introduced with OS 3.0 with no intention to backport this. We can break down the solution into following action items -

• Code change in OpenSearch's StreamInput, StreamOutput classes to add Writers and Read methods respectively for third party classes directly involved in serialization within security plugin. [will update the list below]
  • InetSocketAddress
• Re-implement Base4Helper::serialize and Base64Helper.deserialize methods to use custom serialization.
• Handle communication b/w old and new nodes during version upgrade
• Introduce safe class checks for the alternative (de)serialization implementation (this may no longer be needed as unsupported classes will fail to be serialized)
• End to end testing, especially the version upgrade scenario
• Run OSB tests to see how the various throughputs/latencies change (exploring different workloads where the impact would be much more pronounced, encountering high variance for the tests already performed)
• Finalise the OS version in which the change will be released (version code be used in the version upgrade handling logic to identify old nodes)

I've raised an initial draft PR for serialization using protostuff and working towards testing the version upgrade scenario (from OS2.5 to OS2.7). Currently, the change is assumed to be introduced as part of OS2.7 release for testing purpose. We may need to bump up this version.
Will raise another PR with custom serialization.

Next Steps

• Review the benchmarks and maybe explore any other potential alternatives.

[parasjain1]

Discovered an issue with deserialization of InetSocketAddress with protostuff. The constructor of this class instantiates holder which is a transient field and is ignored by protostuff during serialization. Post deserializing with protostuff the holder field is null. Looking into this.

[parasjain1]

This works with FST and JDK Serialization as they have a check for the presence of writeObject and readObject method and use the same in case it's present. This is true for InetSocketAddress.

Protostuff, while constructing the RuntimeSchema for InetSocketAddress ignores the transient field holder, and given that it follows proto format, it does not address the presence of writeObject and readObject methods.

[parasjain1]

Started an issue with protostuff - protostuff/protostuff#349 to here from what the maintainers have to say.

[parasjain1]

Updated the issue description with more accurate benchmarks results, and highlighted the protostuff issue.

[mgodwan]

Will a delegate schema help here with proto issue? https://protostuff.github.io/documentation/runtime-schema-delegate?

[parasjain1]

Delegate will enable us to specify how we want to write and read a certain object to/from the I/O. It'd have been helpful if the objects that we are dealing with are maintained by us. In this case InetSocketAddress is part of java.net package and does not fully expose all properties that we'll need to construct the object back.

For eg. InetSocketAddress::writeObject also writes the InetAddress property. The InetAddress::family attribute is not exposed publicly, though it's written out by InetAddress::writeObject.

[stephen-crawford]

Hi @parasjain1, thank you for taking the time to file this issue. Your findings look convincing and the maintainers would be happy to review a pull request swapping to a different serialization method.

[parasjain1]

Sure @scrawfor99. I'm still evaluating the best of the available alternatives and will be working on the PR. Thanks!

[parasjain1]

Will a delegate schema help here with proto issue? https://protostuff.github.io/documentation/runtime-schema-delegate?

Revisited the InetSocketAddress class. Although it does not expose the InetAddress::family field, the same can be re-constructed safely by passing values of other fields to the constructor of InetSocketAddress.