Monitor threads with onstat –u output

Use the onstat –u command to display information about active threads that require a database server task-control block.

Active threads include threads that belong to user sessions, as well as some that correspond to database server daemons (for example, page cleaners). Figure 1 shows an example of onstat -u output.

Also use the onstat -u command to determine if a user is waiting for a resource or holding too many locks, or to get an idea of how much I/O the user has performed.

The utility output displays the following information:

The address of each thread
Flags that indicate the present state of the thread (for example, waiting for a buffer or waiting for a checkpoint), whether the thread is the primary thread for a session, and what type of thread it is (for example, user thread, daemon thread, and so on)
For information on these flags, see the HCL Informix® Administrator's Reference.
The session ID and user login ID for the session to which the thread belongs
A session ID of 0 indicates a daemon thread.
Whether the thread is waiting for a specific resource and the address of that resource
The number of locks that the thread is holding
The number of read calls and the number of write calls that the thread has executed
The maximum number of current, active user threads

If you execute onstat -u while the database server is performing fast recovery, several database server threads might appear in the display.

Figure 1. onstat -u output

Userthreads
address  flags   sessid   user     tty      wait     tout locks nreads   nwrites
80eb8c   ---P--D 0        informix -        0        0    0     33       19
80ef18   ---P--F 0        informix -        0        0    0     0        0
80f2a4   ---P--B 3        informix -        0        0    0     0        0
80f630   ---P--D 0        informix -        0        0    0     0        0
80fd48   ---P--- 45       chrisw   ttyp3    0        0    1     573      237
810460   ------- 10       chrisw   ttyp2    0        0    1     1        0
810b78   ---PR-- 42       chrisw   ttyp3    0        0    1     595      243
810f04   Y------ 10       chrisw   ttyp2    beacf8   0    1     1        0
811290   ---P--- 47       chrisw   ttyp3    0        0    2     585      235
81161c   ---PR-- 46       chrisw   ttyp3    0        0    1     571      239
8119a8   Y------ 10       chrisw   ttyp2    a8a944   0    1     1        0
81244c   ---P--- 43       chrisw   ttyp3    0        0    2     588      230
8127d8   ----R-- 10       chrisw   ttyp2    0        0    1     1        0
812b64   ---P--- 10       chrisw   ttyp2    0        0    1     20       0
812ef0   ---PR-- 44       chrisw   ttyp3    0        0    1     587      227
 15 active, 20 total, 17 maximum concurrent