5 threads (for the default singleton) can be created even when SlackConfig#statsEnabled is false

[seratch]

Developers can disable API clients' metrics management by setting SlackConfig#statsEnabled to false. Even in this case, the default SlackConfig object creation (as a static field in the class) starts 5 threads and those threads are unused. See the repro steps below for details.

Reproducible in:

any versions

The Slack SDK version

any versions

Java Runtime version

any versions

OS info

any versions

Steps to reproduce:

Running the following code and checking the thread dump.

SlackConfig config = new SlackConfig();
config.setStatsEnabled(false);
Slack slack = Slack.getInstance(config);

Expected result:

No threads under a "slack-api-metrics" thread group are created.

Actual result:

5 threads for the default singleton SlackConfig instance are created.

[jfbenckhuijsen]

Also running into this issue. I'm working on a slack app using Quarkus, where I hope the native compilation will allow the app to start up fast enough for the 3-second limit on processing the Events API.

Running native compilation requires exclusion of these default classes because of the threads started (which Quarkus doesn't allow)

[seratch]

@jfbenckhuijsen Thanks for sharing this. However, even when this issue is resolved, this SDK still does not support native builds. Refer to https://github.com/slackapi/java-slack-sdk/issues/1009 for more details. We are not planning to add native supports as long as gson project is ready for it.