8346383: Cannot use DllMain in libdt_socket for static builds

[magicus]

To be able to properly support static builds on Windows in JDK-8346377, we cannot use DllMain, for two reasons:

1. This is not called for statically linked libraries, and
2. There are multiple DllMain definitions throughout the JDK native libraries, causing name collisions.

While it could have been possible to keep the DllMain function for non-static builds and just use an alternative solution for static builds, I think it is preferable to have a single solution that works as well for both static and dynamic builds.

On top of this, the existing solution was contrary to Microsoft recommendations, which state: "The WSACleanup function typically leads to protocol-specific helper DLLs being unloaded. As a result, the WSACleanup function should not be called from the DllMain function in a application DLL. This can potentially cause deadlocks. "

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Issue

• JDK-8346383: Cannot use DllMain in libdt_socket for static builds (Bug - P3)

Reviewers

• Serguei Spitsyn (@sspitsyn - Reviewer) Review applies to ea53ff03
• David Holmes (@dholmes-ora - Reviewer)

Reviewing

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[bridgekeeper]

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[magicus]

I'm not sure what tests to run for this change, apart from tier1. I am open to suggestions.

[openjdk]

@magicus This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8346383: Cannot use DllMain in libdt_socket for static builds

Reviewed-by: dholmes, sspitsyn

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At the time when this comment was updated there had been 229 new commits pushed to the master branch:

• 13a1775: 8344146: Remove temporary font file tracking code.
• 61dc07c: 8346869: [AIX] Add regression test for handling 4 Byte aligned doubles in structures
• 13e1ea5: 8346038: [REDO] - [C1] LIR Operations with one input should be implemented as LIR_Op1
• 7c883c2: 8347605: Use spec tag to refer to IEEE 754 standard
• 4e0ffda: 8346972: Test java/nio/channels/FileChannel/LoopingTruncate.java fails sometimes with IOException: There is not enough space on the disk
• e0f2f4b: 8313396: Portable implementation of FORBID_C_FUNCTION and ALLOW_C_FUNCTION
• b0c131e: 8345368: java/io/File/createTempFile/SpecialTempFile.java fails on Windows Server 2025
• a7915bb: 8346468: SM cleanup of common test library
• f67b703: 8347427: JTabbedPane/8134116/Bug8134116.java has no license header
• 062f2dc: 8347554: [BACKOUT] C2: implement optimization for series of Add of unique value
• ... and 219 more: https://git.openjdk.org/jdk/compare/dbffe33251da4472945d97ab54c7e3354d7f42d2...master

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[openjdk]

@magicus The following label will be automatically applied to this pull request:

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[mlbridge]

Webrevs

• 01: Full - Incremental (7edefdd9)
• 00: Full (ea53ff03)

[magicus]

Can I get any reviewers for this?

[sspitsyn]

This looks good but needs copyright year updates.

[dholmes-ora]

Exactly when will WSACleanup get called via the atexit handler versus when it gets called today? I suspect it is sooner than when DllMain with DLL_PROCESS_DETACH would be called. In which case do we now risk tearing down socket support whilst it may still be in use?

[magicus]

My understanding is that it is later. But I am also not sure if this is well-specified or just an implementation detail. I'd say our code is broken if we rely on anything working between DLL_PROCESS_DETACH and atexit handlers are called. I seriously doubt that is the case.

[dholmes-ora]

I will click approve but I think we need to keep a careful eye out for odd network related failures during shutdown.

Thanks

[magicus]

/integrate

[openjdk]

Going to push as commit d3a7ac2.
Since your change was applied there have been 229 commits pushed to the master branch:

• 13a1775: 8344146: Remove temporary font file tracking code.
• 61dc07c: 8346869: [AIX] Add regression test for handling 4 Byte aligned doubles in structures
• 13e1ea5: 8346038: [REDO] - [C1] LIR Operations with one input should be implemented as LIR_Op1
• 7c883c2: 8347605: Use spec tag to refer to IEEE 754 standard
• 4e0ffda: 8346972: Test java/nio/channels/FileChannel/LoopingTruncate.java fails sometimes with IOException: There is not enough space on the disk
• e0f2f4b: 8313396: Portable implementation of FORBID_C_FUNCTION and ALLOW_C_FUNCTION
• b0c131e: 8345368: java/io/File/createTempFile/SpecialTempFile.java fails on Windows Server 2025
• a7915bb: 8346468: SM cleanup of common test library
• f67b703: 8347427: JTabbedPane/8134116/Bug8134116.java has no license header
• 062f2dc: 8347554: [BACKOUT] C2: implement optimization for series of Add of unique value
• ... and 219 more: https://git.openjdk.org/jdk/compare/dbffe33251da4472945d97ab54c7e3354d7f42d2...master

Your commit was automatically rebased without conflicts.

[openjdk]

@magicus Pushed as commit d3a7ac2.

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