[RFR] 8184328: JDK8u131 socketRead0 hang at SSL read

Xuelei Fan xuelei.fan at oracle.com
Fri Sep 15 14:07:45 UTC 2017

On 9/15/2017 7:00 AM, Rob McKenna wrote:
> When we call close() on the SSLSocket that calls close() on the
> underlying java Socket which closes the native socket.
Sorry, I did not get the point.  Please see the close() implementation 
of SSLSocket (sun.security.ssl.SSLSocketImpl.close()) about the details.


>      -Rob
> On 13/09/17 04:09, Xuelei Fan wrote:
>> It's a little bit complicated for layered SSL connections.  Application can
>> build a SSL connection on existing socket (we call it layered SSL
>> connections).  The problem scenarios make look like:
>> 1. open a socket for applications.
>> 2. established a SSL connection on the existing socket.
>> 3. close the SSL connection, but leaving data in the socket.
>> 4. establish another SSL connection on the socket, as the existing data in
>> the socket, the connection cannot be established.
>> 5. establish another app connection on the socket, as the existing data in
>> the socket, the connection cannot be established.
>> ....
>> Timeout happens even on very high speed network. If a timeout happens and
>> the SSL connection is not closed gracefully, and then the following
>> applications breaks.  IMHO, we need to take care of the case.
>> Xuelei
>> On 9/13/2017 1:06 PM, Chris Hegarty wrote:
>>> Xuelei,
>>> Without diving deeper into this issue, Rob’s suggested approach seems reasonable to me, and better than existing out-of-the-box behaviour. I’m not sure what issues you are thinking of, with using the read timeout in combination with a retry mechanism, in this manner? If the network is so slow, surely there will be other issues with connecting and reading, why is closing any different.
>>> -Chris.
>>>> On 13 Sep 2017, at 16:52, Rob McKenna <rob.mckenna at oracle.com> wrote:
>>>> Hi Xuelei,
>>>> This behaviour is already exposed via the autoclose boolean in:
>>>> https://docs.oracle.com/javase/8/docs/api/javax/net/ssl/SSLSocketFactory.html#createSocket-java.net.Socket-java.io.InputStream-boolean-
>>>> My position would be that allowing 5 retries allows us to say with some
>>>> confidence that we're not going to get a close_notify from the server.
>>>> If this is the case I think its reasonable to close the connection.
>>>> W.r.t. a separate timeout, the underlying mechanics of a close already
>>>> depend on the readTimeout in this situation. (waiting on a close_notify
>>>> requires performing a read so the read timeout makes sense in this
>>>> context) I'm happy to alter that but I think that the combination of
>>>> a timeout and a retry count is straightforward and lower impact.
>>>> In my opinion the default behaviour of potentially hanging indefinitely
>>>> is worse than the alternative here. (bearing in mind that we are closing
>>>> the underlying socket)
>>>> I'll file a CSR as soon as we settle on the direction this fix will
>>>> take.
>>>>     -Rob
>>>> On 13/09/17 05:52, Xuelei Fan wrote:
>>>>> In theory, there are intermittent compatibility problems as this update may
>>>>> not close the SSL connection over the existing socket layer gracefully, even
>>>>> for high speed networking environments, while the underlying socket is
>>>>> alive.  The impact could be serious in some environment.
>>>>> For safe, I may suggest turn this countermeasure off by default.  And
>>>>> providing options to turn on this countermeasure:
>>>>> 1. Close the SSL connection gracefully by default; or
>>>>> 2. Close the SSL connection after a timeout.
>>>>> It's hardly to say 5 times receiving timeout is better/safer than timeout
>>>>> once in this context.  As you have already had a system property to control,
>>>>> you may be able to use options other than the customized socket receiving
>>>>> timeout, so that the closing timeout is not mixed/confused/dependent on/with
>>>>> the receiving timeout.
>>>>> Put all together:
>>>>> 1. define a closing timeout, for example "jdk.tls.waitForClose".
>>>>> 2. the property default value is zero, no behavior changes.
>>>>> 3. applications can set positive milliseconds value for the property. The
>>>>> SSL connection will be closed in the set milliseconds (or about the maximum
>>>>> value between SO_TIMEOUT and closing timeout), the connection is not grant
>>>>> to be gracefully.
>>>>> What do you think?
>>>>> BTW, please file a CSR as this update is introducing an external system
>>>>> property.
>>>>> Thanks,
>>>>> Xuelei
>>>>> On 9/11/2017 3:29 PM, Rob McKenna wrote:
>>>>>> Hi folks,
>>>>>> In high latency environments a client SSLSocket with autoClose set to false
>>>>>> can hang indefinitely if it does not correctly recieve a close_notify
>>>>> >from the server.
>>>>>> In order to rectify this situation I would like to suggest that we
>>>>>> implement an integer JDK property (jdk.tls.closeRetries) which instructs
>>>>>> waitForClose to attempt the close no more times than the value of the
>>>>>> property. I would also suggest that 5 is a reasonable default.
>>>>>> Note: each attempt times out based on the value of
>>>>>> Socket.setSoTimeout(int timeout).
>>>>>> Also, the behaviour here is similar to that of waitForClose() when
>>>>>> autoClose is set to true, less the retries.
>>>>>> http://cr.openjdk.java.net/~robm/8184328/webrev.01/
>>>>>>     -Rob

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