IBM Support

Users are dropped from Sametime meetings at random intervals

Technote (troubleshooting)


Problem

Attendees are being dropped from a Lotus Sametime meeting randomly. This drop is not specific to connection type (that is, LAN or WAN). Not all connections are being broken at the same time. Not all attendees are disconnected. The problem is intermittent.

Cause

If the server has not received a response from the Meeting Room Client within 60 seconds after sending a polling packet, then the connection is considered stale and will be terminated.

Diagnosing the problem

To determine if this problem affects your Sametime meetings, collect a Java Console (see "How to enable debug for the Sametime meeting server") from an affected user and look for prints similar to these:


    [MM/YY HR:MIN:SEC] STConnectionAuto(Outbound)
    STPacketHandlerOutput processPackets: EXCEPTION -
    java.net.SocketException: Connection reset by peer: socket write error
    [MM/YY HR:MIN:SEC] STConnectionAuto(Outbound) ConnectionStatus
    connectionLost: exception: java.net.SocketException: Connection reset by
    peer: socket write error

Collect the summary.diag file, and look for the following in the debug output is:

    P:05900 T:6048 MM/YY HR:MIN:SEC [ Error] [MCSNC ] Socket::Poll:
    TC = 0x1000006: Packet not received from client in 60 seconds,
    terminating connection

This is where the client gets dropped from the server.

Memory errors or warnings might also be printed:
    P:05908 T:6076 04/13/09 12:32:09.382 [Warnin] [STMM ] 0x09504c40 -
    Cannot allocate memory array - maximum reached - max:192 a:192 s:104

These messages are informational. They indicate Sametime is working as intended and are occurring because of slow connections causing buffers to fill up with packets waiting to be sent. The net result is the buffer pool is unable to provide the required buffers. Increasing the pool will not help overcome the slow connections.

Resolving the problem

In at least two instances, disabling the Nagle algorithm has resolved the issue. The Notes.ini parameter debug_pd_nagle_off=1 turns off the Nagle algorithm on the server.

(The Nagle algorithm, a standard feature of TCP, combines groups smaller similar packets to reduce per packet overhead and also to reduce the number of packets on the wire.)

Document information

More support for: Lotus End of Support Products
IBM Sametime

Software version: 7.5, 7.5.1, 8.0

Operating system(s): AIX, IBM i, Linux, Solaris, Windows

Reference #: 1384169

Modified date: 01 May 2009