I wanted to run a code (or an external executable) for a specified amount of time. For example, in Fortran I can
call system('./run')
Is there a way I can restrict its run to let's say 10 seconds, for example as follows
call system('./run', 10)
I want to do it from inside the Fortran code, example above is for system command, but I want to do it also for some other subroutines of my code. for example,
call performComputation(10)
where performComputation will be able to run only for 10 seconds. The system it will run on is Linux.
thanks!
EDITED
Ah, I see - you want to call a part of the current program a limited time. I see a number of options for that...
Option 1
Modify the subroutines you want to run for a limited time so they take an additional parameter, which is the number of seconds they may run. Then modify the subroutine to get the system time at the start, and then in their processing loop get the time again and break out of the loop and return to the caller if the time difference exceeds the maximum allowed number of seconds.
On the downside, this requires you to change every subroutine. It will exit the subroutine cleanly though.
Option 2
Take advantage of a threading library - e.g. pthreads. When you want to call a subroutine with a timeout, create a new thread that runs alongside your main program in parallel and execute the subroutine inside that thread of execution. Then in your main program, sleep for 10 seconds and then kill the thread that is running your subroutine.
This is quite easy and doesn't require changes to all your subroutines. It is not that elegant in that it chops the legs off your subroutine at some random point, maybe when it is least expecting it.
Imagine time running down the page in the following example, and the main program actions are on the left and the subroutine actions are on the right.
MAIN SUBROUTINE YOUR_SUB
... something ..
... something ...
f_pthread_create(,,,YOUR_SUB,) start processing
sleep(10) ... calculate ...
... calculate ...
... calculate ...
f_pthread_kill()
... something ..
... something ...
Option 3
Abstract out the subroutines you want to call and place them into their own separate executables, then proceed as per my original answer below.
Whichever option you choose, you are going to have to think about how you get the results from the subroutine you are calling - will it store them in a file? Does the main program need to access them? Are they in global variables? The reason is that if you are going to follow options 2 or 3, there will not be a return value from the subroutine.
Original Answer
If you don't have timeout, you can do
call system('./run & sleep 10; kill $!')
Yes there is a way. take a look at the linux command timeout
# run command for 10 seconds and then send it SIGTERM kill message
# if not finished.
call system('timeout 10 ./run')
Example
# finishes in 10 seconds with a return code of 0 to indicate success.
sleep 10
# finishes in 1 second with a return code of `124` to indicate timed out.
timeout 1 sleep 10
You can also choose the type of kill signal you want to send by specifying the -s parameter. See man timeout for more info.
Related
I have sript for 3 lcd display on my rassbery pi, and have problem with
time sleep function.
I would like to have a pause only for screen 3 ( after 10s show different data ), and the other LCD should run normaly, without time sleep - pause
example :
# LCD1
mylcd1.lcd_display_string("TEMP1:",1,0)
mylcd1.lcd_display_string(str(temp1),1,5)
mylcd1.lcd_display_string ("%s" %time.strftime("%H:%M:%S"),3, 0)
# LCD2
mylcd2.lcd_display_string("TEMP2:",1,0)
mylcd2.lcd_display_string(str(temp2),1,5)
# LCD3
mylcd3.lcd_clear()
mylcd3.lcd_display_string("TEMP3:",1,0)
mylcd3.lcd_display_string(str(temp3),1,5)
time.sleep(10)
mylcd3.lcd_clear()
mylcd3.lcd_display_string("DIM:",1,0)
mylcd3.lcd_display_string(str(dp1),1,4)
In this example is problem time in LCD1, It does not run smoothly, it has to wait 10s, and temperature data on LCD 1 and LCD 2 it must be refreshed in real time without delay....
Thank you for help!
I would say an easy way to go about this is have your LCD's that need to be updated running in a loop, and have a variable that is keeping track of the time.
Then within your loop have an if statement checking if the time % 10 seconds == 0 then run the refresh of the Screen that needs the delay.
I forgot to write .... the compete code is already in loop...
I want add time.sleep only for part for LCD3 ...
LCD3 change data every 10 sec.
I use Fortran to do some scientific computation. I use HPC. As we know, when we submit jobs in a HPC job scheduler, we also specify the wall clock time limit for our jobs. However, when the time is up, if the job is still writing output data, it will be terminated and it will cause some 'NUL' values in the data, causing trouble for the post-processing:
So, could we set an internal mechanism that our job can stop itself peacefully some time before the end of HPC allowance time?
Related Question: How to skip reading "NUL" value in MATLAB's textscan function?
After realizing what you are asking I found out that I implemented similar functionality in my program very recently (commit https://bitbucket.org/LadaF/elmm/commits/f10a1b3421a3dd14fdcbe165aa70bf5c5001413f). But I still have to set the time limit manually.
The most important part:
time_stepping%clock_time_limit is the time limit in seconds. Count the number of system clock ticks corresponding to that:
call system_clock(count_rate = timer_rate)
call system_clock(count_max = timer_max_count)
timer_count_time_limit = int( min(time_stepping%clock_time_limit &
* real(timer_rate, knd), &
real(timer_max_count, knd) * 0.999_dbl) &
, dbl)
Start the timer
call system_clock(count = time_steps_timer_count_start)
Check the timer and exit the main loop with error_exit set to .true. if the time is up
if (mod(time_step,time_stepping%check_period)==0) then
if (master) then
error_exit = time_steps_timer_count_2 - time_steps_timer_count_start > timer_count_time_limit
if (error_exit) write(*,*) "Maximum clock time exceeded."
end if
MPI_Bcast the error exit to other processes
if (error_exit) exit
end if
Now, you may want to get the time limit from your scheduler automatically. That will vary between different job scheduling softwares. There will be an environment variable like $PBS_WALLTIME. See Get walltime in a PBS job script but check your scheduler's manual.
You can read this variable using GET_ENVIRONMENT_VARIABLE()
I am trying to use REFPROPs HSFLSH subroutine to compute properties for steam.
When the same state property is calculated over multiple iterations
(fixed enthalpy and entropy (Enthalpy = 50000 J/mol & Entropy = 125 J/mol),
the time taken to compute using HSFLSH after every 4th/5th iteration increases to about 0.15 ms against negligible amount of time for other iterations. This is turning problematic because my program places call to this subroutine over several thousand times. Thus leading to abnormally huge program run times.
The program used to generate the above log is here:
C refprop check
program time_check
parameter(ncmax=20)
dimension x(ncmax)
real hkj,skj
character hrf*3, herr*255
character*255 hf(ncmax),hfmix
C
C SETUP FOR WATER
C
nc=1 !Number of components
hf(1)='water.fld' !Fluid name
hfmix='hmx.bnc' !Mixture file name
hrf='DEF' !Reference state (DEF means default)
call setup(nc,hf,hfmix,hrf,ierr,herr)
if (ierr.ne.0) write (*,*) herr
call INFO(1,wm,ttp,tnbp,tc,pc,dc,zc,acf,dip,rgas)
write(*,*) 'Mol weight ', wm
h = 50000.0
s = 125.0
c
C
DO I=1,NCMAX
x(I) = 0
END DO
C ******************************************************
C THIS IS THE ACTUAL CALL PLACE
C ******************************************************
do I=1,100
call cpu_time(tstrt)
CALL HSFLSH(h,s,x,T_TEMP,P_TEMP,RHO_TEMP,dl,dv,xliq,xvap,
& WET_TEMP,e,
& cv,cp,VS_TEMP,ierr,herr)
call cpu_time(tstop)
write(*,*),I,' time taken to run hsflsh routine= ',tstop - tstrt
end do
stop
end
(of course you will need the FORTRAN FILES, which unfortunately I cannot share since REFPROP isn't open source)
Can someone help me figure out why is this happening.?
P.S : The above code was compiled using gfortran -fdefault-real-8
UPDATE
I tried using system_clock to time my computations as suggested by #Ross below. The results are uniform across the loop (image below). I will have to find alternate ways to improve computation speed I guess (Sigh!)
I don't have a concrete answer, but this sort of behaviour looks like what I would expect if all calls really took around 3 ms, but your call to CPU_TIME doesn't register anything below around 15 ms. Do you see any output with time taken less than, say 10 ms? Of particular interest to me is the approximately even spacing between calls that return nonzero time - it's about even at 5.
CPU timing can be a tricky business. I recommended in a comment that you try system_clock, which can be higher precision than CPU_TIME. You said it doesn't work, but I'm unconvinced. Did you pass a long integer to system_clock? What was the count_rate for your system? Were all the times still either 15 or 0 ms?
I want to run a function for example func() exactly 1 time per second. However the running time of func() is about 500 ms. How Can I do that? I know if the running time of the function is low, I can write a while loop in func() and sleep() for 1 second after each execution. But now, the running time is high. What should I do to ensure the func() run exactly 1 time per second? Thanks.
Yo do:
Take the current time in start_time.
Perform your job
Take the current time in end_time
Wait for (1 second + start_time - end_time)
That way, you can perform your tasks every seconds reliably. If the task takes less time, you will wait longer and vice versa. Note however that this assumes that your task takes always less than 1 sec. to execute. In the real code, you want to check for that before the sleep statement.
Implementation details depend on the platform.
Note that using this method still results in a small drift due to the time it takes to compute step 4. A more accurate alternative would be to synchronize on integer multiple of one second. That way, over 1000s of cycles you would not drift.
It depends on the level of accuracy you need.
If you want a brute, easy to code solution, you can get the time before first run of the function and save it in some variable (start_time). Create repeat index count variable (repeat_number) that stores next repeat number. Then you can do kinda this:
1) next_run_time = ++repeat_number*1sec + start_time;
2) func();
3) wait_time = next_run_time - current_time;
4) sleep(wait_time)
5) goto 1;
This approach disables accumulation of time error on each iteration.
But for the real application you should find some event framework or library.
I hope someone could help me with this (And english is not my native language so I'm sorry in advance for any grammar or spelling mistakes):
As part of a project I'm coding, I need to time some commands. More specifically: I have 2 sets of commands (Lets call them set A and set B) - I need to to execute set A, then wait for a specific number of milliseconds (calculated in set A), then execute set B. I did it using the Sleep(time) command between the sets.
Now, I need to incorporate another set of commands (Set C) that will run in a loop in the time between the sets A and B instead of simply doing nothing. Meaning, instead of the time the program was idle before (waiting the specified number of milliseconds) I need it to loop the C set - but the catch is that it has to loop C exactly the same time it would have waited in the idle time.
How can I do this without using threads? (And generally keep it as simple as possible)
I guess the "work-time" for the set of commands in C is known. And C is a loop which can/shall finish when the wait time has expired.
In this case I'd suggest to use a performance counter to count down the wait time. Depending on what is calculated and what overhaed is introduced in C the accuracy to obtain can be in the microseconds range.
Pseudo code:
Delay = 1000
Do A
CounterBegin = GetCounter()
// and now the C loop
while ((GetCounter() - CounterBegin) < Delay) {
Do C
}
Do B
Note: The counter values are to be converted into times by using the counter frequency. See the link above to get the details.