Kris, This issue would be more appropriate on the net-dev or nio-dev mailing lists. So, I'll cross post it and bcc off jdk8-dev.
Thanks, -Chris. On 11/18/11 08:22 AM, 撒迦 wrote: > 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) > > ________________________________ > This email (including any attachments) is confidential and may be legally > privileged. If you received this email in error, please delete it immediately > and do not copy it or use it for any purpose or disclose its contents to any > other person. Thank you. > > 本电邮(包括任何附件)可能含有机密资料并受法律保护。如您不是正确的收件人，请您立即删除本邮件。请不要将本电邮进行复制并用作任何其他用途、或透露本邮件之内容。谢谢。
