Output Description

The -u option provides the following output for each user thread:

address

is the shared-memory address of the user thread (in the user table). Compare this address with the addresses displayed in the -s output (latches); the -b, -B, and -X output (buffers); and the -k output (locks) to learn what resources this thread is holding or waiting for.

flags

provides the status of the session.

The flag codes for position 1:

B

Waiting for a buffer

C

Waiting for a checkpoint

G

Waiting for a write of the logical-log buffer

L

Waiting for a lock

S

Waiting for mutex

T

Waiting for a transaction

Y

Waiting for condition

X

Waiting for a transaction cleanup (rollback)

DEFUNCT

The thread has incurred a serious assertion failure, and has been suspended to allow other threads to continue their work. If this status flag appears, refer to Thread Suspension, for instructions.

The flag code for position 2:

*

Transaction active during an I/O failure

The flag code for position 3:

A

A dbspace backup thread

For other values that appear here, see the third position of flag codes for the -x option.

The flag code for position 4:

P

Primary thread for a session

The flag codes for position 5:

R

Reading

X

Transaction is XA prepared. The database server (in an X/Open DTP environment) is prepared to commit or is currently in the process of committing.

The flag codes for position 7:

B

A B-tree cleaner thread

C

Terminated user thread waiting for cleanup

D

A daemon thread

F

A page-cleaner thread

sessid

is the session identification number. During operations such as parallel sorting and parallel index building, a session might have many user threads associated with it. For this reason, the session ID identifies each unique session.

user

is the user login name (derived from the operating system).

tty

indicates the tty that the user is using (derived from the operating system).

wait

if the user thread is waiting for a specific latch or lock, this field displays the address of the resource. Use this address to map to information provided in the -s (latch) or -k (lock) output.

tout

is the number of seconds left in the current wait. If the value is 0, the user thread is not waiting for a latch or lock. If the value is -1, the user thread is in an indefinite wait.

locks

is the number of locks that the user thread is holding. (The -k output should include a listing for each lock held.)

nreads

is the number of disk reads that the user thread has executed.

nwrites

is the number of write calls that the user thread has executed. All write calls are writes to the shared-memory buffer cache.

The last line of onstat -u output displays the maximum number of concurrent user threads that were allocated since you initialized the database server. For example, the last line of the example onstat -u output is as follows:

12 active, 128 total, 18 maximum concurrent

The last part of the line, 18 maximum concurrent, indicates that the maximum number of user threads that were running concurrently since you initialized the database server is 18.