Simplify debugging of Undertow transferTo issue #25310

[JiangTChen]

Since undertowHttpServer conflicts with other HTTPServers. Temporarily bypass with transferToForUndertow. It's better than return and pass.

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[sbrannen]

Hi @JiangTChen,

Thanks for submitting your first PR to the Spring Framework!

Since undertowHttpServer conflicts with other HTTPServers. Temporarily bypass with transferToForUndertow.

Can you briefly expound on the first statement and explain how your workaround (the second statement) solves the problem?

[sbrannen]

Please note that your PR fails the build:

MultipartIntegrationTests > transferToWithUndertow() FAILED
    java.lang.AssertionError at MessageFormatter.java:115

In light of that, I'm marking this as a draft.

[JiangTChen]

@sbrannen Thanks for your review.
I found that the pass rate was not 100%. You can use @RepeatedTest(100) instead of @test to verify it.
There are three kinds of exceptions. I think the root cause is about "Connection prematurely closed BEFORE response".
It's very tricky, I'm not sure if it's a configuration of AbstractHttpHandlerIntegrationTests#startServer
or undertow bug.
I will keep digging.
Should we add @Disable on transferToWithUndertow() first, to instead of return pass.
It can alter others and help to fix.

Thanks

[sbrannen]

I found that the pass rate was not 100%. You can use @RepeatedTest(100) instead of @test to verify it. There are three kinds of exceptions. I think the root cause is about "Connection prematurely closed BEFORE response". It's very tricky, I'm not sure if it's a configuration of AbstractHttpHandlerIntegrationTests#startServer or undertow bug. I will keep digging.

Thanks for the explanation.

Should we add @Disable on transferToWithUndertow() first, to instead of return pass. It can alter others and help to fix.

I originally thought you were proposing a fix for Undertow, but since that's not the case, yes adding @Disabled to the new test method is a must.

And please do continue investigating the root cause of the Undertow issue. We haven't had the time to do that ourselves, and we'd be grateful for a fix from the community.

[JiangTChen]

Hi @sbrannen,
Please help to review again.
Thanks.

[sbrannen]

This has been merged into main.

Feel free to continue to investigate the cause of the issue and report your findings in #25310.

Thanks