[Bug]: Simple POST request from a cURL client fails with NPE for a Ballerina service ran using lang master

[TharmiganK]

Description

When we invoke a Ballerina service which runs with lang master, then the a simple POST request fails with the following error:

java.lang.NullPointerException: Cannot invoke "io.ballerina.runtime.internal.scheduling.Scheduler.createFuture(io.ballerina.runtime.internal.scheduling.Strand, io.ballerina.runtime.api.async.Callback, java.util.Map, io.ballerina.runtime.api.types.Type, String, io.ballerina.runtime.api.async.StrandMetadata)

Note: This is not happening if we invoke the service by adding a Ballerina test in the same package. This might be the reason for not identifying this issue in the full build pipeline PR check

Steps to Reproduce

Service code used to reproduce this issue:

import ballerina/http;

type Album readonly & record {|
    string title;
    string artist;
|};

final table<Album> key(title) albums = table [
    {title: "Blue Train", artist: "John Coltrane"},
    {title: "Sarah Vaughan and Clifford Brown", artist: "Sarah Vaughan"}
];

service / on new http:Listener(9090) {
    resource function get albums() returns Album[] {
        return albums.toArray();
    }

    resource function post albums(Album album) returns Album|http:Conflict {
        if albums.hasKey(album.title) {
            return http:CONFLICT;
        }
        albums.add(album);
        return album;
    }
}

Steps to reproduce this issue:

1. I have used the following timestamped version of lang - 2201.9.0-20240120-003700-f65e7994. This is also reproducible when we build the lang master and use it in the http module

2. Clone the ballerina-http repository and update the lang version in the gradle.properties file

3. Run ./gradlew clean build -x test -x check. This will create a temporary distribution in the target path in the repo root.

4. Use the bal command in that target directory to run the above Ballerina service

5. Make a cURL request: curl -v "http://localhost:9090/albums" -d '{"title": "test", "artist": "test"}' -H "content-type: application/json"

Affected Version(s)

Ballerina SwanLake Update 9

OS, DB, other environment details and versions

No response

Related area

-> Runtime

Related issue(s) (optional)

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Suggested label(s) (optional)

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Suggested assignee(s) (optional)

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[HindujaB]

I checked the cause for this not happening in the bal test environment. For bal run when we invoke the moduleStart to start listening, there are no jobs to be run further in the same scheduler. Therefore, it is garbage collected and set to null. For bal test this scenario won't happen as we invoke testExecute after the moduleStart which will use the same scheduler.

[github-actions]

This issue is NOT closed with a proper Reason/ label. Make sure to add proper reason label before closing. Please add or leave a comment with the proper reason label now.

      - Reason/EngineeringMistake - The issue occurred due to a mistake made in the past.
      - Reason/Regression - The issue has introduced a regression.
      - Reason/MultipleComponentInteraction - Issue occured due to interactions in multiple components.
      - Reason/Complex - Issue occurred due to complex scenario.
      - Reason/Invalid - Issue is invalid.
      - Reason/Other - None of the above cases.