RFR: 8237388: serviceability/dcmd/framework/VMVersionTest.java fails with connection refused error.

[Serguei Spitsyn]

On Thu, 27 May 2021 23:00:56 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

> nsk test framework for testing jdi/jdwp assumes that the test launch debuggee first and then creates IOPipe to communicate with debuggee (debugger listens, debugee connects to the IOPipe socket).
> This makes possible failure when debuggee tries to connect before debugger starts listening.
> The fix changes logic of the tests to start listening on IOPipe socket before launch debuggee.
> Other tests which use IOPipe/SocketIOPipe and have the same issue (there are a lot of them) will be fixes as separate issues.
> 
> Couple details about the fix:
> - debugee.getPipeServerSocket() just calls binder.getPipeServerSocket(), returned ServerSocket can be changed only by DebugeeBinder.prepareForPipeConnection which is called by some tests;
> - connectingProcess logic is broken. The only place it's used is BasicSocketConnection.checkConnectingProcess, which is called from SocketConnection.continueAttach. But continueAttach is called from debuggee code (listening == false) while connectingProcess is set only from debugger code (listening == true). So it didn't work and I dropped it.
> 
> Testing: all tests which use IOPipe/SocketIOPipe classes:
> - test/hotspot/jtreg/serviceability/dcmd/framework
> - test/hotspot/jtreg/vmTestbase/nsk/jdi
> - test/hotspot/jtreg/vmTestbase/nsk/jdwp

Hi Alex,
This is nice refactoring. It looks good to me.
The fix has a potential to introduce new regressions.
I hope you run all the impacted tests on all platforms.
Thanks,
Serguei

test/hotspot/jtreg/vmTestbase/nsk/share/jpda/SocketIOPipe.java line 275:

> 273:         if (listening) {
> 274:             // listenerThread == null means the test is not updated yet
> 275:             // to start IOPipe listening before launching debuggee.

I like this workaround for non-updated tests. This spot can be simplified after all tests got updated.

test/hotspot/jtreg/vmTestbase/nsk/share/jpda/SocketIOPipe.java line 279:

> 277:                 // start listening and accept connection on the current thread
> 278:                 listenerThread = new ListenerThread();
> 279:                 listenerThread.run();

It is not clear, why `listenerThread.run()` is used instead of `listenerThread.start()` as at the line 257.

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Marked as reviewed by sspitsyn (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/4235