SNA Print Server May Take 100 Percent of CPU Processing Time

• Microsoft SNA Server, versions 4.0, 4.0 SP1, 4.0 SP2

SYMPTOMS

Under certain circumstances, the SNA Print Service's buffer can overrun. This causes a spike in the CPU's processor time.

CAUSE

The mainframe may continue to send data to the SNA Print Server after receiving sense data from the SNA Server. This may cause the SnaPrint buffer to overflow.

RESOLUTION

The SNA Print Server has been modified so that if a message arrives that will not fit into the print buffer and the session is closed, the message is ignored. Previously, the SNA Print Server continually attempted to put the message into the print buffer, and this caused the CPU spike. When the session is closed properly with an End Bracket (EB) or UNBIND, this problem does not occur.

To resolve this problem, obtain the latest service pack for Microsoft SNA Server version 4.0. For additional information, please see the following article in the Microsoft Knowledge Base:

Q215838 How to Obtain the Latest SNA Server Version 4.0 Service Pack

WORKAROUND

The best solution is to correct the datastream from the mainframe. If this is not possible, restarting the SNA Print Server will temporarily resolve the problem.

STATUS

This problem was first corrected in Microsoft SNA Server 4.0 Service Pack 3.

MORE INFORMATION

This is the scenario in which this problem was reported:

The SNA print session was configured to use a short job timeout value because the mainframe was not issuing an UNBIND or EB at the end of the print jobs. When a job timed out, the print session was successfully closed, but the mainframe continued to send data for the next job. Because the print session was closed, the SNA Print Service rejected the message with a NACK-1, sense data 0802 - Intervention required. The mainframe continued to send data messages, overrunning the SNA print buffer. The CPU spiked at 100%.

The mainframe should not have sent data after receiving the sense data from the SNA Server. The proper behavior is to either re-BIND the session or send an end bracket followed by a begin bracket.

Additional query words:

Keywords : kbDSupport
Version : WINDOWS:4.0,4.0 SP1,4.0 SP2
Platform : WINDOWS
Issue type : kbbug