dlr 2002/12/03 09:22:27
Modified: src/java/org/apache/xmlrpc WebServer.java
Log:
Applied patch by Ed Tellman <[EMAIL PROTECTED]>. Here's what Ed has to
say about the change:
"I am using Windows 2000, jdk 1.4.1.
I wrote a simple performance test which repeatedly makes an XML-RPC
call, to see how many calls I could make each second.
I was surprised to find that in my system enabling HTTP keep alive
dramatically reduced the performance, instead of improving it as I
expected. I did a bit of experimenting, and found that setting the
TCP no-delay option on the socket helped quite a bit. After I did
this, the performance with keep alive was about twice as good as the
performance without it."
Ed suggests that we provide a global flag to gate the toggling of the
TCP_NODELAY socket option, but we'll hold off on that until someone
actually voices a need for such a flag. Apache httpd 2.0 also sets
this socket option, relying on APR to determine whether the underlying
platform's TCP stack supports it. XML-RPC will go out on a limb and
rely on Java to do the Right Thing (cross your fingers, folks!).
In case you're curious, here's a reasonably good description of
TCP_NODELAY from CVS revision 1.102 of httpd-2.0/server/mpm_common.c:
"The Nagle algorithm says that we should delay sending partial
packets in hopes of getting more data. We don't want to do
this; we are not telnet. There are bad interactions between
persistent connections and Nagle's algorithm that have very severe
performance penalties. (Failing to disable Nagle is not much of a
problem with simple HTTP.)
In spite of these problems, failure here is not a shooting offense."
A comment in /usr/include/netinet/tcp.h on my RedHat 7.3 box speaks
similarly of TCP_NODELAY:
"Don't delay send to coalesce packets."
Considering that things still work okay with Nagle's algorithm active,
I've added handling of SocketException around setting of the
TCP_NODELAY flag which reports the error and keeps on chuggin'.
Revision Changes Path
1.22 +10 -0 xml-rpc/src/java/org/apache/xmlrpc/WebServer.java
Index: WebServer.java
===================================================================
RCS file: /home/cvs/xml-rpc/src/java/org/apache/xmlrpc/WebServer.java,v
retrieving revision 1.21
retrieving revision 1.22
diff -u -u -r1.21 -r1.22
--- WebServer.java 10 Oct 2002 00:24:12 -0000 1.21
+++ WebServer.java 3 Dec 2002 17:22:26 -0000 1.22
@@ -64,6 +64,7 @@
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
+import java.net.SocketException;
import java.util.EmptyStackException;
import java.util.Stack;
import java.util.StringTokenizer;
@@ -482,6 +483,15 @@
try
{
Socket socket = serverSocket.accept();
+ try
+ {
+ socket.setTcpNoDelay(true);
+ }
+ catch (SocketException socketOptEx)
+ {
+ System.err.println(socketOptEx);
+ }
+
if (allowConnection(socket))
{
Runner runner = getRunner();
