Bug in sun.nio.ch.SolarisEventPort#port_dissociate

[David M. Lloyd]

On 06/16/2017 10:36 AM, Alan Bateman wrote:
> On 14/06/2017 15:32, David M. Lloyd wrote:
>>
>> It's coming from a user so my information is limited but I can 
>> establish that it is happening under load, and I think it corresponds 
>> to an open socket being abruptly closed in another thread.
>>
>> I am not sure whether I can get it down to a test case though. I'll 
>> see if I can get access to a Solaris system for testing.
>>
> If you get some idea on the conditions when this occurs then it would be useful.  To make sure there is nothing obvious, I ran JDK tests on Solaris 11.3 system with the port Selector as the default.

I'll see if I can find out more.  I have gained access to a test 
environment but I haven't been able to reproduce it in isolation either.

> All the tests pass. I 
> can't think of a scenario where port_dissociate could fail with EBADF. 

It's not EBADF but EBADFD, if that makes a difference.  I've been 
working off of various GC-related hypotheses but without knowing the 
exact conditions that precipitate EBADFD, I'm really shooting in the 
dark.  One would have to examine the kernel sources to get that answer.

> It is correct to ignore ENOENT as that occurs then the file descriptor 
> registered with the port is closed by dup'ing.

Is it possible that this operation is non-atomic in the kernel, such 
that the descriptor is briefly in an intermediate state before being 
replaced by the placeholder?

-- 
- DML