-------- Original Message --------
Subject: Re: Suppress creation of SocksSocketImpl in SocketAdaptor's
constructor
Date: Fri, 18 Nov 2011 16:38:28 +0800
From: Krystal Mok <rednaxel...@gmail.com>
To: 撒迦 <sa...@taobao.com>
CC: jdk8-...@openjdk.java.net <jdk8-...@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 撒迦 <sa...@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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