Overview of the Task States

Use

The task state shows whether a task is active and which action it is currently executing.

Overview of the Task States

Name

Description

AsynClose

Task is closing I/O ports after backup or restore

AsynCntl

Task is determining parameters or initializing a backup device

AsynIO

Task is executing an asynchronous I/O operation (during backup or restore)

AsynOpen

Task is opening I/O ports for the backup or restore

AsynWaitRead/Write

Task is waiting for the end of an I/O operation during backup or restore

Command reply

Task is sending the result of a request to the application

Command wait

Database session without a request

Connect wait

Free database session

DcomObjCalled

Task is executing a database procedure or a COM object

Diaginit

Task is initializing the database-internal trace file

Inactive

Task is in an initial state and has no resources (such as a stack)

InsertEvent

Task is generating an event

IO wait (W/R)

Task is waiting for the result of an I/O operation (W: write, R: read)

Locked

Task was locked as the kernel was shut down (to avoid this task being rescheduled)

RescheduleMsec

Short-term wait situation, task runs again automatically after a predefined time span (in microseconds)

Runnable

Task can run now, but has been displaced due to long runtime or priority of another task

Running

Task is running, using CPU

sleep

Short-term wait situation, task runs again automatically after a predefined time span

Stopped

Task was suspended by the kernel and is waiting to run again

Terminated

Task or database session was ended

UNKNOWN

Task state is unknown

Vattach

Task is opening I/O ports (volumes, normal operation)

Vbegexcl

Task is waiting to enter a protected area

Vdetach

Task is closing I/O ports (volumes, normal operation)

Vdevsize

Task is determining the size of a volume or formatting a volume

Vdualvectorio

Task is performing a vector I/O operation (read or write) on two volumes in parallel

Vendexcl

Task is leaving a protected area

VenterRWRegion

Task is waiting to enter a protected area (reader/writer region)

Vfclose

Task is closing a file

Vfopen

Task is opening a file

Vfwrite

Task is writing to a file

VleaveRWRegion

Task is leaving a protected area (reader/writer region)

Vopmsg

Task is writing a message to one of the following database files: knldiag, knldiag.err, opmsg[n]

Vrelease

Task is ending the database session

Vshutdown

Task is changing the operational state of the database instance from ONLINE to ADMIN

Vsuspend

Task is suspended and waiting to be awoken explicitly by another task (Vresume)

There are special Vsuspend wait situations that are displayed under their own names. The following list shows the most important of these states.

TableRootExcl: can occur while accessing B* trees that represent permanent data
A task is trying to set an exclusive lock on the root page of a B* tree but has to wait due to a lock collision. Tasks request exclusive locks on B* trees for structure-changing operations such as tree balancing, among other operations.

TableRootShare: can occur while accessing B* trees that represent permanent data
A task is trying to set a shared lock on the root page of a B* tree but has to wait due to a lock collision. As a rule, all operations on a B* tree begin with a shared lock, which is refined as the operation descends into the B* tree, that is, it is extended to become an exclusive or shared lock on the leaf level.

TableNodeExcl, TableNodeShare: analogous wait states for lock collisions on the leaf level

For B* trees that represent an index or temporary data, there are similar states, such as InvRootExcl, InvRootShare, InvNodeExcl, TempRootExcl and TempRootExcl.

For page chains, there are similar states, such as ObjRootExcl, ObjNodeExcl, ObjNodeShare, UndoRootExcl, UndoRootShare and UndoNodeExcl.

DC OvFlow: The data cache is operating at capacity and cannot accept any new data. Only when pages have been written from the data cache to the volumes can the data cache accept new pages. If you frequently observe DC OvFlow states, check whether your data cache is large enough or the I/O system too slow.

LogQ FULL: The log queues are operating at capacity and cannot accept any new redo log entries. Only when the log writer has written data from the log queues to the log area can the log queues accept log entries again. If you frequently observe LogQ Full states, check whether your log queues are too small or the I/O system too slow.

DB FULL: The data area is full and cannot accept any more pages. Add a new data volume.

Vvectorio

Task is executing a vector I/O operation (read or write)

Vwait

Task is waiting to be awoken explicitly by another task (Vsignal) Example: task is waiting for an SQL lock

WaitForEvent

Task is waiting for an event

Activities

To display information about tasks, use the Database Manager or XCONS or in SAP systems the database assistant or liveCache assistant. See

?     Database Manager GUI, Displaying Database Sessions

?     Database Manager CLI, show

?     XCONS documentation

?     Database Administration in CCMS: MaxDB, Task Manager

See also:

Overview of Tasks

Process Structure