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Analysis of TCP traffic might show packets delayed of 200ms on the receiving side for some commands. This is caused by delay ack. When the DELAYACKS is active, the ACK for a particular inbound packet with data will be delayed 200ms seconds if the inbound packet has a payload of less than the MSS. Looking at the sniffer trace, the payload at the time when you see the 200ms is about 300 bytes (smaller than the MSS), which supports the theory that the DELAYACKS is active. To turn off the delay ack on the MVS side, you can code NODELAYACKS on the TCPCONFIG statement (global) or you can code it on the PORT reservation statement for the particular port being used. However it will be useful to be able to set it on the socket in RSE as well using _socket.setTcpNoDelay(true);
A test with NODELAY shows great improvement on performance
Is this request specific to dstore? Does it affect the client only, or server only, or both?
Problem is on both sides client and server and I assume it is specific to dstore. I have worked on this issue with David McKnight who will add more information.
Created attachment 196749 [details] patch to provide TCPNODELAY option
Xuan, could you please review this?
The fix looks good. Thanks.
Thanks for the review, Xuan. I've committed the change to cvs.
Created attachment 196872 [details] patch fixing the build on J2SE-1.4 This checkin broke the build, because dstore.core must still be J2SE-1.4 compliant and Boolean.parseBoolean() is not in J2SE-1.4 I fixed the issue by converting to Boolean.valueOf(s).booleanValue(). Please also apply this fix to the 3.2.2+ Stream, which is currently also broken. And, please ensure that a J2SE-1.4 JVM is registered in your Workspace (Preferences : Java : JVM's) in order to detect such issues in your workspace.
I released the change for 3.3RC3. Shouldn't we document system properties like the new DSTORE_TCP_NO_DELAY somewhere ?
Created attachment 196888 [details] patch with option described in constants file Other properties like this have been defined in a constants file and described there as this patch does.
I released the update for 3.3rc3, but cannot build currently due to bug 347744 .
