Used in: unicast-listener, multicast-listener, packet-publisher.


Specifies the size of the OS buffer for datagram sockets.

Performance Impact

Large inbound buffers help insulate the Coherence network layer from JVM pauses caused by the Java Garbage Collector. While the JVM is paused, Coherence is unable to dequeue packets from any inbound socket. If the pause is long enough to cause the packet buffer to overflow, the packet reception will be delayed as the the originating node will need to detect the packet loss and retransmit the packet(s).

It's just a hint

The OS will only treat the specified value as a hint, and is not required to allocate the specified amount. In the event that less space is allocated then requested Coherence will issue a warning and continue to operate with the constrained buffer, which may degrade performance.


The following table describes the elements you can define within the packet-buffer element.

Element Required/Optional Description
<maximum-packets> Required For unicast-listener, multicast-listener and packet-publisher: Specifies the number of packets of maximum size that the datagram socket will be asked to size itself to buffer. See SO_SNDBUF and SO_RCVBUF. Actual buffer sizes may be smaller if the underlying socket implementation cannot support more than a certain size. Defaults are 32 for publishing, 64 for multicast listening, and 1428 for unicast listening.