Fwd: Re: Suppress creation of SocksSocketImpl in SocketAdaptor's constructor (original) (raw)

Chris Hegarty chris.hegarty at oracle.com
Fri Nov 18 02:57:21 PST 2011

Hi Kris,

I think this change should be fine, but I would like Alan to comment also.

Thanks, -Chris.

On 11/18/11 10:44 AM, Chris Hegarty wrote:

-------- Original Message -------- Subject: Re: Suppress creation of SocksSocketImpl in SocketAdaptor's constructor Date: Fri, 18 Nov 2011 16:38:28 +0800 From: Krystal Mok<rednaxelafx at gmail.com> To: ÈöåÈ<sajia at taobao.com> CC: jdk8-dev at openjdk.java.net<jdk8-dev at openjdk.java.net> Oops, looks like my company email stripped the attachment. Here's that patch again: diff -r 00e2c88e2234 src/share/classes/sun/nio/ch/SocketAdaptor.java --- a/src/share/classes/sun/nio/ch/SocketAdaptor.java Thu Nov 17 10:46:02 2011 -0800 +++ b/src/share/classes/sun/nio/ch/SocketAdaptor.java Fri Nov 18 15:37:20 2011 +0800 @@ -57,13 +57,17 @@ // Timeout "option" value for reads private volatile int timeout = 0; - // ## super will create a useless impl - private SocketAdaptor(SocketChannelImpl sc) { + private SocketAdaptor(SocketChannelImpl sc) throws SocketException { + super((SocketImpl) null); this.sc = sc; } public static Socket create(SocketChannelImpl sc) { - return new SocketAdaptor(sc); + try { + return new SocketAdaptor(sc); + } catch (SocketException e) { + throw new RuntimeException("should not reach here"); + } } public SocketChannel getChannel() { - Kris 2011/11/18 ÈöåÈ<sajia at taobao.com> Hi all,

I'd like to propose the following change to JDK's sun.nio.ch.SocketAdaptor: In OpenJDK 6, 7 and 8, sun.nio.ch.SocketAdaptor is used to adapt a SocketChannelImpl to a java.net.Socket. A comment in the constructor of SocketAdaptor says "super will create a useless impl", but it actually doesn't have to. AFAICT the SocksSocketImpl instance created here really isn't used at all in SocketAdaptor, unless someone invokes non-public methods on java.net.Socket via reflection. The attached patch is to get rid of creation of the useless SocksSocketImpl. At a glance, creating a useless SocksSocketImpl for every SocketAdaptor seems innocent. But that's not the case when the allocation rate/heap memory pressure is high. SocksSocketImpl has a finalizer (inherited from PlainSocketImpl), and when: * old generation is large * there are a lot of ready-to-die SocksSocketImpl instances these instances can be queued up in the finalizer queue, which increases the heap pressure. In one of our Hadoop NameNode nodes in production, excessive SocksSocketImpl instances had been causing frequent CMS collections + long reference processing pause. Using this patch helps side-steping the problem. I don't have a bug ID for this yet. Could anyone kindly open a bug for this? Regards, Kris Mok Software Engineer, Taobao (http://www.taobao.com)

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