onstat -g nsc command: Print current shared memory connection information

Use the onstat -g nsc command to display information about shared memory connections either for all of the current connections or for a specified connection ID.

Figure 1: Syntax:

If no client_id is provided, information about all current shared memory connections to the database server is given. If a client_id is provided then this command gives more detailed information about the shared memory connection with that ID.

Example output

This is output of onstat -g nsc with no client_id. It shows that there is only one user currently connecting to the database server through shared memory. That connection has an ID of 0.

Figure 2: onstat -g nsc command output

                                                                                
  clientid  clientPID      state #serverbufs #clientbufs    #rdwrts             
         0       6031  Connected           4           4         12

This example shows output from running the command using a client_id of 0.

Figure 3: onstat -g nsc command with client id output

Network Shared Memory Status for Client: 0                                      
                                                                                
    clientid    clientPID        state  #serverbufs  #clientbufs      #rdwrts   
           0        18949    Connected            4            4       447048   
                                                                                
     needbuf        segid        semid       semnum     be_semid    be_semnum   
           0         1303       851969            0       851969           10   
                                                                                
  be_curread  be_curwrite   fe_curread  fe_curwrite                             
          -1            1            0            2                             
                                                                                
 be_nextread be_nextwrite  fe_nextread fe_nextwrite                             
           2            2            4            3                             
                                                                                
readyqueue                                                                      
  -1   -1   -1   -1   -1   -1   -1   -1   -1   -1   -1                          

     Server Buffers                             Client Buffers                  
  i: bufid     status   offset  fe_addr         bufid     status   offset  fe_addr
  0:     4      inuse     4474   804474             0      avail     3424   803424
  1:     5      inuse     4888   804888             1      avail     3838   803838
  2:     6      avail     4c9c   804c9c             2      inuse     3c4c   803c4c
  3:     7      avail     50b0   8050b0             3      avail     4060   804060
  4:    -1       free        0        0            -1       free        0       0
  5:    -1       free        0        0            -1       free        0       0

Output description

clientid

Server assigned ID

clientPID

Client process ID

state

State of connection

Connected: The client has established a connection with the server.
Con1: The server has successfully set up a connection with the client, but the client has not yet been notified of it.
Waiting: The server is in the process of setting up a connection with the client.
Reject: Client connection has been rejected by the server, normally because the server is shutting down or not yet in on-line mode.
Closed: Server has closed the connection with the client. Client might not be aware of the fact yet.
Not connected: Server is initializing internal structures for the connection.
Unknown: Connection has been closed and the client is aware of the fact. Server is cleaning up internal structures.

#serverbufs

Database server buffers currently allocated

#clientbufs

Client buffers currently allocated

#rdwrts

The total number of reads and writes performed through this connection since it was created.

The following items are only in the output if you run the onstat -g nsc command with a client_id:

needbuf

Indicates if server is waiting for a buffer to be freed

0: False
1: True

segid

Shared memory segment ID

semid

Semaphore ID

semnum

Semaphore number in the semaphore ID

be_semid

Backend semaphore ID

be_semnum

Backend semaphore number in the semaphore ID

be_curread

ID of backend buffer being read

be_curwrite

ID of backend buffer being written

fe_curread

ID of frontend buffer being read

fe_currwrite

ID of frontend buffer being written

be_nextread

ID of next backend buffer to be read

be_nextwrite

ID of next backend buffer to be written

fe_nextread

ID of next frontend buffer to be read

fe_nextwrite

ID of next frontend buffer to be written

readyqueue

Queue of the shared memory buffer ids

Buffers
i: Internal location key of message buffer
bufid: Message buffer ID
status: Status of message buffer
offset: Offset of memory buffer in shared memory segments
fe_addr: Frontend address of message buffer