Thursday, January 24, 2013

UnicastUdpSocket failed to set receive buffer size to 1428 packets

The following messages have been found from the WebLogic Server output:

<Jan 24, 2013 2:32:04 PM PST> <Warning> <Coherence> <BEA-000000> <2013-01-24 14:32:04.325/37.402 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=[ACTIVE] ExecuteThread: '0' for queue: 'weblogic.kernel.Default (self-tuning)', member=n/a): UnicastUdpSocket failed to set receive buffer size to 1428 packets (2096304 bytes); actual size is 357 packets (524288 bytes). Consult your OS documentation regarding increasing the maximum socket buffer size. Proceeding with the actual value may cause sub-optimal performance.>

As warned: if you proceed with the actual receive buffer value, it may cause sub-optimal performance for your application. In this case, it's our OAM server.

What's OAM Server?

Oracle Access Manager Server[2] is a runtime engine used to provide shared services for access such as Authentication/Authorization service, session management, token processing, and single sign-on. OAM Server runs on one of WebLogic's Managed servers, such as oam_server1.

How to Fix the Issue?

To fix the issue, you can increase TCP max buffer size.  For example, our original values were:


After increasing both read and write buffer to bigger size (note that they are in bytes) as follows:

net.core.rmem_max = 4194304
net.core.wmem_max = 4194304

We don't see the above warning anymore.  You can find the above TCP buffer sizes in:

  • /etc/sysctl.config

After login as a root, you can modify them and issue
  • sysctl -p 
to enable sysctl data immediately.

Similarly you can issue the following Linux commands to achieve the same effects:
  • sysctl -w net.core.rmem_max=4194304
  • sysctl -w net.core.wmem_max=4194304

As suggest in [3], you may want to tune other TCP parameters for better networking performance.


  1. 'UdpSocket failed to set receive buffer size to 1428 packets' Error Due to Coherence Tuning
  2. Oracle Identity and Access Manager 11g for Administrators
  3. Linux Tuning

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