How to wait milliseconds within SPL?
SangGyu Jeong asked how to sleep for milliseconds in SPL on AIX, where system sleep and yieldn did not work. David Williams suggested a C UDR; Andreas Legner and Paul Watson warned it must yield (mi_yield) or the CPU VP is lost to the OS. Art Kagel offered a gettimeofday UDR; Paul posted a clock_nanosleep loop with mi_yield that worked on Linux.
Auto-generated by Claude from the posts below — may be imperfect; read the full thread.
Hello All,
Is there a function in SPL that works similar to sleep?
I used system ('sleep 5') , sysmaster:yieldn(), sysadmin:yieldn() functions, etc, but it doesn't seem to work in milisecond units. Because it is an AIX environment, usleep or nsleep cannot be used.
Any ideas?
drop procedure myproc;
create procedure myproc()
insert into tmp1 select dbinfo('utc_to_datetime',sh_curtime) from sysmaster:sysshmvals;select sysmaster:yieldn(0.01) y from sysmaster:sysdual into temp ifxtmp1 with no log;
insert into tmp1 select dbinfo('utc_to_datetime',sh_curtime) from sysmaster:sysshmvals;
drop table ifxtmp1;end procedure;
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SangGyu Jeong
Software Engineer
Infrasoft
Seoul Korea, Republic of
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#Informix
Hi, Write a C UDR which calls whatever OS function can do sub-second sleeps. A C UDR can be written something similar to (if you use gcc): https://justdaveinfo.wordpress.com/2015/04/26/simple-informix-c-udr-on-centos-6-6/ Regards, David. ------------------------------ David Williams ------------------------------
Problem with this probably would be that, instead of yielding the Informix thread (to another one) while 'sleeping', you'd yield the cpu vp (to the OS). ------------------------------ Andreas Legner ------------------------------
Don't do that – your engine will not love you for it. You need to do very small micro sleeps with lots of mi_yield otherwise you will probably lose the VP you are running in to the OS Cheers Paul
I have a UDR that calls gettimeofday() to return microsecond resolution time. One could loop on that call until the desired sub-second time had elapsed.
> execute function adbm_gettimeofday();(expression)
2021-12-14 17:00:21.93423
1 row(s) retrieved.
If anyone is interested in the source, email me.
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Art S. Kagel, President and Principal Consultant
ASK Database Management Corp.
www.askdbmgt.com
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The high level logic in the UDR is for(i=HowLongMS; i--;) { usleep(1) Mi_yield() } You don't want to directly sleep for 25ms, the engine can do a lot in 25ms J You could look at nanosleep but I suspect that is not what you want. Cheers Paul
Been playing on my Linux, usleep (1) maps to nanosleep(0,1000) – live and learn
Appears to work under Linux void oni_sleep(mi_integer ms) { struct timespec ts; int i; long next_tick; clock_getres(CLOCK_MONOTONIC, &ts); clock_gettime(CLOCK_MONOTONIC, &ts); for(i=ms;i--;) { next_tick = (ts.tv_sec * 1000000000L + ts.tv_nsec) + 1000000; ts.tv_sec = next_tick / 1000000000L; ts.tv_nsec = next_tick % 1000000000L; clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &ts, NULL); mi_yield(); } }