8212132: (dc) Remove DatagramChannelImpl finalize method

[Alan Bateman]

On 27/10/2019 17:49, Martin Buchholz wrote:
> :
>
> (also, there's no read-write-lock as one would expect from seeing a 
> readLock and a writeLock.  But I have no better name (hmmm   maybe 
> readerLock and writerLock?))
They have been named "readLock" and "writeLock" since 1.4 but you may 
have a point.

>
> Wearing my finalization/reachability hat, it looks to me like 
> technically a method like
> public int write(ByteBuffer buf)
> needs a reachabilityFence to prevent fd from being closed while in 
> use, but in practice no misbehavior will ever be provoked, in part 
> because hotspot refuses to hoist final fields into locals.
The channel implementation has a strong reference to the FileDescriptor 
so I think you are suggesting that, at least in theory, the channel (fd, 
locks, ...) could be GC'ed while a thread is a read/write/send/receive 
method. I don't see how the compiler could look through the 
endRead/endWrite methods but I'll study it further. Also if we had 
issues here then I would expect the IBM folks to speak up as they tend 
to find them with their J9 VM.

-Alan

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