IBM 000-8697 Manual Do Utilizador

IBM Informix OnLine Database Server Administrator’s Guide

kill -9

command. If

you execute the

kill -9

command and generate a

SIGKILL

signal while that

server process is holding a latch or is in a critical section of a transaction,
OnLine aborts with an immediate shutdown to preserve data consistency.

 signal. An application tool

process can, on occasion, get the attention of the database server process by
sending a signal that the server process can trap. The only signal that the
server process cannot trap is the

SIGKILL

signal. Therefore, there is no reason

for an administrator to use the

SIGKILL

 signal to terminate application

processes. When you kill an application process with

 kill -9

, you can

create an orphaned database server process.

If you suspect a database server process has been orphaned, follow these
steps to verify that the process is not doing any database work before you
attempt to kill it:

Obtain the database server process identification (pid) number from
tbstat -u

 output.

Check that the process is not in a critical section. Look at the third-
position flag of the tbstat -u output. If the process flag is X, do not kill
the process; if you do, OnLine aborts with an immediate shutdown.

Check that the process is not holding a latch. Obtain the address of
the process from the tbstat -u output. Execute tbstat -s to look at a
summary of latch information. Verify that the address of this process
is not listed as the owner of any latch. If the process address is
associated with a latch, do not kill the process; if you do, OnLine
aborts with an immediate shutdown.

If the server process is not in a critical section and is not holding a
latch, user informix or root can kill the process with the command
tbmode -z pid

.

Do not kill a database server process that is in a critical section or is holding
a latch; if you do, OnLine initiates an abort. Instead, wait until the server
process has exited the section or released the latch.

If the server process does not exit the section or release the latch, user
informix

 or root can execute tbmode -k to detach all processes from shared

memory and take OnLine to offline mode.