Improve handling of concurrent requests in WebSocketGraphQlClient

[rstoyanchev]

Attempts to send requests concurrently may fail with:

java.lang.IllegalStateException: Failed to send request: FAIL_NON_SERIALIZED

This is because we are using the Reactor Sinks API which expect serial sending with external synchronization. The current implementation however simply retries 100 times and fails if it keeps losing out.

This needs to be improved and was also reported in #369 (comment).

[viral-kondhia]

I just wonder why it does not happen with HttpGraphQLClient
Please excuse me as I don't have understanding about the sinks API.

[rstoyanchev]

GraphQL over WebSocket uses a single, shared connection for all requests. GraphQL over HTTP on the other hand makes an independent HTTP request for each GraphQL request and underlying that is a connection pool. So WebSocket is more efficient but is also a little more challenging to implement.

[rstoyanchev]

@viral-kondhia this should be fixed now. If you would like to give it a try with 1.0.0-SNAPSHOT and confirm it works for you, that would be great.

[viral-kondhia]

@rstoyanchev Yes I think it's fixed
I did maven update and then restarted my service and tested 40 request per second with same socket graphql client..

[rstoyanchev]

Thanks for trying the snapshots and confirming!