Monitoring Threads
Onstat -g ath Print all Threads
This option to onstat will print all information about all user threads in the instance.
$onstat -g ath Informix Dynamic Server Version 7.30.UC3 -- On-Line -- Up 2 days 22:12:02 -- 18464 Kbytes Threads: tid Tcb rstcb prty status vp-class name 2 c19ab050 0 2 sleeping forever 3lio vp 0 3 c19ab2c0 0 2 sleeping forever 4pio vp 0 4 c19ab558 0 2 sleeping forever 5aio vp 0 5 cl9ab7f0 0 2 sleeping forever 6msc vp 0 6 c19aba88 0 2 sleeping forever 7aio vp 1 7 c19abe40 cl8da018 4 sleeping secs: 1 1cpu main_loop() 8 cl9c3810 0 2 running 1cpu soctcppoll 9 cl9c3e20 0 3 sleeping forever 1cpu soctcplst 10 cl9c64c8 cl8da4cc 2 sleeping forever 1cpu flush_sub(0) 11 cl9c6c20 0 2 sleeping forever 8aio vp 2 12 cl9c6eb8 0 2 sleeping forever 9aio vp 3 13 c19C7150 0 2 sleeping forever 10aio vp 4 14 cl9c73e8 0 2 sleeping forever llaio vp 5 15 cl9c7680 0 2 sleeping forever 12aio vp 6 16 cl9c7918 0 2 sleeping forever 13aio vp 7 17 cl9c7bb0 0 2 sleeping forever 14aio vp 8 18 c19c7e48 0 2 sleeping forever 15aio vp 9 19 cl9db128 0 2 sleeping forever 16aio vp 10 20 c19db390 0 2 sleeping forever 17aio vp 11 21 c19db628 0 2 sleeping forever 18aio vp 12 22 cl9db8c0 0 2 sleeping forever 19aio vp 13 23 c19dbb58 0 2 sleeping forever 20aio vp 14 24 c19dbdf0 0 2 sleeping forever 21aio vp 15 25 cl9de228 0 2 sleeping forever 22aio vp 16 26 cl9de468 0 2 sleeping forever 23aio vp 17 27 cl9deeb0 c18da980 3 sleeping forever 1cpu aslogflush 28 cl9df268 cl8dae34 2 sleeping secs: 43 1cpu btclean 44 cla23560 cl8dbc50 4 sleeping secs: 1 1cpu onmode_mon 70 c1be8bd0 c18db79c 2 cond wait networm 1cpu sqlexec 76 c1bf0ef8 c18db2e8 2 cond wait networm 1cpu sqlexec
Meanings of the fields are:
| • tid | Thread ID | |
| • tcb | Address of the thread within the thread control block | |
| • rstcb | Address within the RSAM task-control block | |
| • prty | Priority of the thread | |
| • status | Status of the thread | |
| Common status flags: | ||
| cond wait: netnorm | Engine thread is waiting for client to give a command over tcp | |
| cond wait: smread | Engine thread is waiting for client to give a command over shared memory connection | |
| • vp-class | VP class and VP number the thread last ran on | |
| • name | Descriptive name of the thread | |
These field meanings are the same for these three onstat -g subcommands:
onstat -g wai
onstat -g ath
onstat -g rea
onstat -g act
Onstat -g wai Print Waiting Threads
This invocation is a subset of the onstat -g ath command that shows only threads which are waiting for something. Field meanings are the same as onstat -g ath (above).
$ onstat –g wai Informix Dynamic Server Version 7.30.UC3 -- On-Line -- Up 2 days 22:12:05 -- 18464 Kbytes Waiting threads: tid tcb rstcb prty status vp-class name 2 c19ab050 0 2 sleeping forever 3lio vp 0 3 c19ab2c0 0 2 sleeping forever 4pio vp 0 4 c19ab558 0 2 sleeping forever 5aio vp 0 5 c19ab7fO 0 2 sleeping forever 6msc vp 0 6 c19aba88 0 2 sleeping forever 7aio vp 1 7 c19abe40 c18da018 4 sleeping sees: 1 1cpu main_loop() 9 c19c3e20 0 3 sleeping forever 1cpu soctcplst 10 c19c64c8 c18da4cc 2 sleeping forever 1cpu flush_sub(0) 11 c19c6c20 0 2 sleeping forever 8aio vp 2 12 c19c6eb8 0 2 sleeping forever 9aio vp 3 13 c19c7150 0 2 sleeping forever 1Oaio vp 4 14 c19c73e8 0 2 sleeping forever 11aio vp 5 15 c19c7680 0 2 sleeping forever 12aio vp 6 16 c19c7918 0 2 sleeping forever 13aio vp 7 17 c19c7bbO 0 2 sleeping forever 14aio vp 8 18 c19c7e48 0 2 sleeping forever 15aio vp 9 19 c19db128 0 2 sleeping forever 16aio vp 10 20 c19db390 0 2 sleeping forever 17aio vp 11 21 c19db628 0 2 sleeping forever 18aio vp 12 22 c19db8cO 0 2 sleeping forever 19aio vp 13 23 c19dbb58 0 2 sleeping forever 20aio vp 14 24 c19dbdfO 0 2 sleeping forever 21aio vp 15 25 c19de228 0 2 sleeping forever 22aio vp 16 26 c19de468 0 2 sleeping forever 23aio vp 17 27 c19deebO c18da980 3 sleeping forever 1cpu aslogflush 28 c19df268 c18dae34 2 sleeping sees: 40 1cpu btclean 44 c1a23560 c1BdbcSO 4 sleeping sees: 1 1cpu onmode_raon 70 c1beSbdO c18db79c 2 cond wait netnorm 1cpu sqlexec 76 c1bfOefS c18db2e8 2 cond wait netnorm 1cpu sqlexec
Onstat -g act Print Active Threads
This is another subset of onstat -g ath, and the field definitions are the same as for the above two thread-listing invocations.
$ onstat -g act Informix Dynamic Server Version 7.30.UC3 -- On-Line -- Up 2 days 22:12:10 -- 18464 Kbytes Running threads: tid tcb rstcb prty status vp-class name 8 c!9c3810 0 2 running 1cpu soctcppoll
Onstat -g rea Print Ready Threads
This is yet another onstat command using the same headings as onstat -g ath. It shows the ready queue, that is, threads that are ready to run and waiting to run. As long as your system is not hardware bound, if you continue to see many threads in a ready state, it may help to add additional virtual processors to service these threads. When adding virtual processors to the engine no longer reduces the ready queue, the system is hardware bound and the only solution is either to put up with decreased performance or to add additional physical CPUs to the system.
$ onstat -g rea Informix Dynamic Server Version 7.30.UC3 -- On-Line -- Up 2 days 22:12:13 -- 18464 Kbytes Ready threads: tid tcb rstcb prty status vp-class name
Onstat -g sle Print all Sleeping Threads
This command lists the threads that are sleeping, waiting for a timeout. Threads that are sleeping forever do not show up here.
$ onstat -g sle
Informix Dynamic Server Version 7.30.UC3 -- On-Line -- Up 2 days 22:12:16 -- 18464 Kbytes
Sleeping threads with timeouts: 3 threads
tid v_proc rstcb name time
7 1 c18da018 main_loop() 1
44 1 c18dbc50 onmode_mon 1
28 1 c18dae34 btclean 29
Field meanings are:
| • tid | Unique thread ID |
| • v_proc | Virtual processor number |
| • rstcb | RSAM task-control block address |
| • name | Type of thread |
| • time | Time left to sleep |
Onstat -g spi Print Spin Locks with Long Spins
This command lists spin locks that have been obtained after more than 10,000 spins for any virtual processor. When a irtual processor spins more than 10,000 times, this is called a longspin.
There are four things that you can do to reduce longspins:
Reduce load on the system
Reduce number of virtual processors
Set no-age parameter
Set processor affinity parameters
$ onstat -g spi Informix Dynamic Server Version 7.30.UC3 -- On-Line -- Up 2 days 22:12:21 -- 18464 Kbytes Spin locks with waits: Num Waits Num Loops Avg Loop/Wait Name 1 1 1.00 vproc vp_lock, id = 1
Onstat -g tpf Print Thread Profiles
$ onstat -g tpf Informix Dynamic Server Version 7.30.UC3 -- On-Line -- Up 2 days 22:14:57 -- 18464 Kbytes Thread profiles tid lkreqs lkw d1 to lgrs isrd iswr isrw isdl isct isrb lx bfr bfw lsus lsmx seq 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 76 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 70 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 31 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
This output is completely undocumented, but I believe that the meanings are as follows: