RFR: 8238274: (sctp) JDK-7118373 is not fixed for SctpChannel

[Masanori Yano]

On Thu, 2 Sep 2021 14:24:24 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

>> Please review this change to the Unix implementations of sun.nio.ch.sctp.Sctp*ChannelImpl#implCloseSelectableChannel() 
>> to be same as SocketChannelImpl at JDK-7118373. (The preClose is missing a check for the ST_KILLED state.)
>
> I have run this change on one of our machines that support SCTP. I did get some intermittent failures with the other SCTP tests - they don't seem much stable - but the new proposed test was failing all the time. I suspect that using `lsof` to figure out whether the file descriptor was closed is not reliable/portable enough. I also tried to modify the test to use /othervm - which is probably a good idea if you don't want your results to be polluted by whatever other test might have run previously/concurrently in the agent VM - but to no avail: the test was still failing 100% of the time.
> @masyano could you figure another way to detect whether the file descriptor has been released?

@dfuch I tried to count `/proc/<PID>/fd`, but there are recorded all fds in the process. I don't know how to pick up only active fds in `/proc/<PID>/fd`. So, I will change to call lsof last one time only (like https://github.com/openjdk/jdk/pull/4621), and counts all unreleased fds.

Could you try this test case?

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PR: https://git.openjdk.java.net/jdk/pull/5274