RFR: 8294375: test/jdk/java/nio/channels/vthread/BlockingChannelOps.java is slow

[Alan Bateman]

On Tue, 27 Sep 2022 11:50:16 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

>> BlockingChannelOps.java and BlockingSocketOps.java test virtual threads doing blocking I/O on channels and java.net sockets.
>> 
>> BlockingChannelOps has 32 tests at this time and takes nearly 120s to run due to several tests that sleep to improve the chances that threads are blocked. These sleeps can be replaced with a poll of the thread state so the test runs in 3-4s. BlockingSocketOps has be changed to do the same time.
>> 
>> In passing, I updated the tests in BlockingSocketOps that bound a ServerSocket to the wildcard address so they bind to the loopback address instead. This helps reduce potential interference in CI environments. I also put a workaround into BlockingChannelOps for macOS where the kernel appears to increase the amount of bytes that can be buffered in the socket sender buffer, it's otherwise too hard to test that socket writes block on that platform.
>
> test/jdk/java/nio/channels/vthread/BlockingChannelOps.java line 206:
> 
>> 204:                         assertTrue(n > 0);
>> 205:                         bb.clear();
>> 206:                     }
> 
> Hello Alan, since `AsynchronousCloseException` is expected here, should we add a `fail` after this loop if we don't receive that exception

It's an infinite loop as write may need to be called many times before it blocks. So you can't put a `fail` after the loop as it will never be executed. If another exception is thrown then the test will fail.

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PR: https://git.openjdk.org/jdk/pull/10427