7133499: (fc) FileChannel.read not preempted by asynchronous close on OS X

[Volker Simonis]

On Mon, Jan 20, 2014 at 10:34 PM, Alan Bateman <Alan.Bateman at oracle.com> wrote:
> On 20/01/2014 19:57, Volker Simonis wrote:
>>
>> Hi Alan,
>>
>> I've tried your patch with our port on AIX.
>> The good news is that it fixes:
>>
>> java/nio/channels/AsynchronousFileChannel/Lock.java
>>
>> on AIX as well.
>>
>> The bad news is, that it doesn't seem to help for:
>>
>> java/nio/channels/AsyncCloseAndInterrupt.java
>>
>> Here's a stack trace of where the VM gets stuck:
>
> In these stack traces then the channels are Pipe.SourceChannel or
> Pipe.SinkChannel where the file descriptor is to one end of a pipe. Are
> these the only cases where you see these hangs? I'm interested to know if
> the async close of SocketChannel and ServerSocketChannel when configured
> blocked also hangs (I will guess that it will as the behavior is likely to
> be the same as pipe).

I also think they will hang, but I'm not sure how to test it. The
java/nio/channels/AsynchronousServerSocketChannel and
java/nio/channels/AsynchronousSocketChannel all pass, but I'm not sure
if they test the same thing.

In the NIO are, I currently (with your change) have problems with the
following tests:

java/nio/channels/AsyncCloseAndInterrupt.java (hangs)
java/nio/channels/AsynchronousChannelGroup/Basic.java (hangs somtimes)
java/nio/channels/AsynchronousChannelGroup/GroupOfOne.java (hangs)
java/nio/channels/AsynchronousChannelGroup/Unbounded.java (hangs somtimes)
java/nio/channels/Selector/RacyDeregister.java (fails)

However, java/nio/channels/AsynchronousChannelGroup/Unbounded.java
hangs in AixPollPort.pollset_poll() (which is our implementation of
AsynchronousChannelGroup) so that may be a completely different
problem. I'm currently try to debug it.

> I have an idea on how to fix this so that the preClose isn't used when the
> channel is configured blocking (or isn't registered with a Selector). The
> patch doesn't use NativeThreadSet because it isn't efficient when the number
> of threads is limited to 1 or 2 (FileChannel uses NativeThreadSet because it
> defines positional read/write and so the number of concurrent reader/writers
> is unlimited).
>

Yes, I'm definitely interested to see and test your patch on AIX.

> I'll send a patch the other channels soon and we can see if this works for
> you. If it does work then I have a bit of a preference to being it in via
> jdk9/dev rather than via the AIX staging forest because the changes impact
> all platforms.

Yes, that's no problem. I think the class library for AIX will be fine
and ready for integration into jdk9/dev without these changes. We can
fix that later and backport it to 8u-dev as required.

> That said, if we being this FileChannel fix for OSX in then
> it means that the platform specific changes would be in, the patch for the
> other platforms shouldn't require porting.
>
> -Alan.
>