I have a python program which I want to execute exactly 30 seconds before every 5th Minute and need to run for 30 seconds only.
Rather than looping and testing if it's the right time over and over again, it's better to calculate the amount of time needed to wait, and sleep until then so the processor can go off and do other things. To do this we still use the datetime module and just a bit of simple math.
from datetime import datetime as dt
from time import sleep
#Calculating sleep interval
t = dt.now()
#seconds in the hour
sec = t.second + t.minute*60
#seconds since the last 5 min interval
sec = sec % 300
#until the next 5 min interval
sec = 300 - sec
#30 sec before that
sec = sec - 30
#if negative we're within 30 sec of 5 minute interval so goto next one
if sec < 0:
sec = sec + 300
sleep(sec)
while True: #loop forever
#with a little re-arranging and boolean math, this can all be condensed to:
t = dt.now()
s = (t.second + 60*t.minute) % 300
sleep(270 - s + 300 * (s >= 270))
#yourFunction()
For very simple cases this should work. If at any point your program crashes, or if the computer re-boots, or a myriad of other reasons, It would be better to use something built in to the OS which will re-start the program automatically, and can handle other conditions such as setting sleep timers, or only executing if a particular user is logged in. On Windows this is task scheduler, on Linux this is typically cron, and OSX is launchd (at least according to developer.apple.com)
If you're running this code indefintley, I'd suggest you look at following Aaron's adivce at look at superuser.com, apple.stackexchange.com or askubuntu.com.
However, if you were going to write this in Python, you could use the datetime module and find the time that's elapsed.
from datetime import datetime
import time
def your_function(t1):
i = 0
# For the next 30 seconds, run your function
while (datetime.now() - t1).seconds =< 30:
i += 1
print(i)
time.sleep(1)
# Run indefintely
while True:
# Record the current time
t1 = datetime.now()
while t1:
# Find the elapsed time in seconds
# If the difference is 270 seconds (4 minutes and 30 seconds)
if (datetime.now()-t1).seconds == 270:
your_function(t1)
# Remove t1 and start at the top of the loop again
t1 = None
Related
I need code that will do this:
def foo():
now = datetime.datetime.utcnow()
# Some code will run that takes a variable amount of time
# (less than 15 minutes)
# This code should run no sooner than 15 minutes after `now`
Note that this is not the same as using time.sleep! time.sleep would halt the entire process, but I need computation in foo() to happen and for foo() to return no sooner than 15 minutes after it begins.
You need to calculate the time between the current time and the desired restart time. Then sleep for that amount of time.
wait_time = 15 # minutes
restart_time = datetime.datetime.now() + datetime.timedelta(minutes=wait_time)
# execute code that takes a long time
# for example, let's just sleep for some time
random_time = random.randint(1, wait_time)
time.sleep(random_time * 60)
print("See you again at ", restart_time)
# Now, calculate how long you need to sleep to resume at restart_time
sleep_time = restart_time - datetime.datetime.now()
# Sleep for that amount of time
time.sleep(sleep_time.total_seconds())
print("Hi, I'm back ", datetime.datetime.now())
datetime is not needed, because we do not need to think in human clock terms (hours, minutes, seconds).
All we need is a number of seconds since any fixed moment in the past and time.monotonic does exactly that.
import time
DELAY = 900 # in seconds
start = time.monotonic()
# computation here
end = time.monotonic()
duration = end - start
time.sleep(DELAY - duration)
Last three lines can be written as time.sleep(start + DELAY - time.monotonic()), I split it for simplicity.
import time
import random
import datetime
wait = random.randint(1, 14)
now = datetime.datetime.utcnow()
print(now)
time.sleep(wait * 60)
now = datetime.datetime.utcnow()
print(now)
I think this solves it.
I'm creating a loop which executes every 5 seconds, starting at the startTime variable and ending at the stopTime variable. However, the code below is disregarding the minutes within my startTime and endTime variables and only executing on the hour. For example, even though my startTime is '1130', the code is executing 11:05, rather than ending the loop. I have the same problem with the endTime variable. If the current time is 12:45, the code still executes even though the endTime variable is '1230'. The code will stop executing at '1300'.
frequency = 5
startTime = '1130'
endTime = '1230'
while True:
now = datetime.now().strftime('%H:%M:%S')
if startTime <= now <= endTime:
print('Loop is working. Time is: ',now)
time.sleep(frequency)
else:
print('Loop is stopped')
break
I live in Central Time, so I tried switching to Eastern timezone by modifying the "now" variable to:
now = datetime.now(timezone('US/Eastern')).strftime('%H:%M:%S.%f %Z')
but I still get the same problem when I substitute eastern times with startTime and endTime when using the eastern datetime.now().
Is executing code at a precise minute possible with strftime()?
EDIT: (this is now the answer to the real question (oops))
If you want to wait till for example 11:30 (which was the real question)
you can calculate the time (in seconds) the program should sleep (and let it sleep for that time):
def wait_till(hour, minute, second=0):
# get system time (and date)
now_time = datetime.datetime.now()
# create time point we are waiting for (this year, this month and this day)
wait_till_time = datetime.datetime(year=now_time.year, month=now_time.month, day=now_time.day, hour=hour, minute=minute, second=second)
# calculate time we want to wait for and convert to seconds
wait_for = (wait_till_time - now_time).total_seconds()
# check if it's going to be tomorrow (if we would sleep for a negative amount of seconds)
if wait_for < 0:
# add one day
wait_till_time = wait_till_time.replace(day=now_time.day+1)
# recalculate (not very beautiful, but i don't know a better way)
wait_for = (wait_till_time - now_time).total_seconds()
# printing this waiting time (in seconds)
print("waiting for",wait_for,"seconds")
# sleeping for that time
time.sleep(wait_for)
# printing the new now time, so we can see how accurate it is
print("its now",datetime.datetime.now())
and say for example:
wait_till(20, 24) # waiting till 20:24 (today)
and get:
waiting for 15.32297 seconds
its now 2019-03-11 20:24:00.003857
which is pretty darn close to what we wanted (20:24:00.000000) and this delay is probably only caused by the calculation lag of formatting the string.
(The old stuff ...)
if it's not important that it takes 100% 5s (but rather 100.04546642303467% --> it will get off a little bit every time) you can just do
import time
frequency = 5 #every 5 seconds
start_time = time.time()
while 1:
elspsed_time = time.time() - start_time
print(elspsed_time)
time.sleep(frequency)
but if you need the 100% you can try this autocorrecting solution:
import time
from threading import Timer
frequency = 5 #every 5 seconds
start_time = time.time()
def what_to_do_after_5s():
elapsed_time = time.time() - start_time
print(elapsed_time)
# next call
Timer(5.0 - (elapsed_time - int(elapsed_time)), what_to_do_after_5s, ()).start()
what_to_do_after_5s()
and we can see that it autocorrects:
0.0
5.000170707702637
10.000272989273071
15.000539064407349
20.001248836517334
25.00046443939209
30.000929355621338
35.00142860412598
40.0007688999176
45.00128436088562
50.00045442581177
55.000683069229126
60.00123882293701
65.00095415115356
70.0015127658844
I am working with Python 2.7 on a Raspberry Pi.
I run a script A which is a for-loop, taking pictures every 30 seconds. Normally, for each iteration, it takes about 5 seconds to capture the scene and save it, and then it sleeps (for about 25 seconds) until the next iteration.
After some time I run a script B which is calculating stuff based on the images taken by script A. So the two scripts are running at the same time. I am not using subprocess or anything, just executing the two scripts separately.
My problem is : when script B is running, script A is slowed down a lot, so that sometimes the first 5 seconds turn into 25-30 seconds and then one iteration can last 40 seconds or more !
Do you know why durations are not respected in script A, and how I can solve this issue ?
Thanks :) !
I believe if you are in a Linux environment you can use nice command in order to balance the cpu usage.for example :
nice --12 script.py
the number above represents the amount of being nice to cpu.it is between -20 and +19.
If the calculation amount of "script B" is nearly always the same you could subtract this time in seconds from the sleep timer.
2.You also could take the runtime in seconds of the scripts, that you will output at the end of their execution. The problem is the python programm will wait for a finished script before continuing.
import subprocess
import time
counter = 0
script_a_runtime = 0
script_b_runtime = 0
while True:
counter += 1
script_a = 0
script_b = 0
script_a_runtime = int(subprocess.check_output(['scripta']))
if counter >=5:
counter = 0
script_b_runtime = int(subprocess.check_output(['scriptb']))
sleeptime = 30 - script_a_runtime - script_b_runtime
if sleeptime:
time.sleep(sleeptime)
3.Timers
import datetime
import time
import subprocess
script_a_runtime = 0
script_b_runtime = 0
while True:
counter += 1
start_a = datetime.datetime.now()
subprocess.check_output(['script_a'])
finish_a = datetime.datetime.now()
script_a_runtime = finish_a - start_a
if counter >= 5:
counter = 0
start_b = datetime.datetime.now()
subprocess.check_output(['script_b'])
finish_b = datetime.datetime.now()
script_b_runtime = finish_b - start_b
sleeptime = 30 - script_a_runtime.seconds - script_b_runtime.seconds
if sleeptime:
time.sleep(sleeptime)
I dont think its a good idea to run those scripts that depend on each other side by side. Also if scriptA/B is not finished before it should be run again there may arise problems.
I need my script to sleep till the next 15 minute hourly interval, e.g. on the hour, quarter past, half past, and quarter too.
It will look something like this
While True:
//do something
sleepy_time = //calculate time to next interval
time.sleep(sleepy_time)
You could write a series of if statements to check what the current minutes past the hour is then do ‘if current < 15’ and ‘if current < 30’ etc but that seems messy and inefficient.
EDIT: Building on #martineau's answer this is the code I went with.
import datetime, time
shouldRun = True
if datetime.datetime.now().minute not in {0, 15, 30, 45}:
shouldRun = False
# Synchronize with the next quarter hour.
while True:
if shouldRun == False:
current_time = datetime.datetime.now()
seconds = 60 - current_time.second
minutes = current_time.minute + 1
snooze = ((15 - minutes%15) * 60) + seconds
print('minutes:', minutes, 'seconds', seconds, ' sleep({}):'.format(snooze))
localtime = time.asctime( time.localtime(time.time()))
print("sleeping at " + localtime)
time.sleep(snooze) # Sleep until next quarter hour.
shouldRun = True
else:
localtime = time.asctime( time.localtime(time.time()))
print("STUFF HAPPENS AT " + localtime)
shouldRun = False
The difference between his answer and this is that this run the else block only once per interval then if the minute is still on the 0, 15, 30, 45 interval calculates the extra seconds to add to the minutes to sleep till the next interval.
You can achieve this using datetime...
A call to datetime.datetime.now() will return a datetime which you can get the current minute past the hour with .minute.
Once we have the number of minutes past the hour, we can do that modulo 15 to get the number of minutes to the next interval of 15.
From here, simply do a call to time.sleep() with that number of minutes times 60 (60 seconds in a minute).
The code for this may look something like:
import datetime, time
minutesToSleep = 15 - datetime.datetime.now().minute % 15
time.sleep(minutesToSleep * 60)
print("time is currently at an interval of 15!")
time.sleep(15*60 - time.time() % (15*60))
15*60 is a numer of seconds in every 15 mins.
time.time() % (15*60) would be the number of seconds passed in the current 15 min frame (since time 0 is 00:00 by definition). It grows from 0 at XX:00, XX:15, XX:30, XX:45, and up to 15*60-1 (actually, 15*60-0.(0)1 — depends on the precision of time measurements), and then starts to grow from 0 again.
15*60 - time.time() % (15*60) is the number of seconds left till the end of the 15-min frame. It, with a basic math, decreases from 15*60 to 0.
So, you need to sleep that many seconds.
However, keep in mind that sleep will not be very precise. It takes some time to process the internal instructions between time.time() is measured, and time.sleep() is actually called on the system level. Nano-fractions of a second, probably. But in most cases it is acceptable.
Also, keep in mind that time.sleep() does not always sleeps for how long it was asked to sleep. It can be waked up by signals sent to the process (e.g., SIGALRM, SIGUSR1, SIGUSR2, etc). So, besides sleeping, also check that the right time has been reached after time.sleep(), and sleep again if it was not.
I don't think #Joe Iddon's answer is quite right, although it's close. Try this (note I commented-out lines I didn't want running and added a for loop to test all possible values of minute):
import datetime, time
# Synchronize with the next quarter hour.
#minutes = datetime.datetime.now().minute
for minutes in range(0, 59):
if minutes not in {0, 15, 30, 45}:
snooze = 15 - minutes%15
print('minutes:', minutes, ' sleep({}):'.format(snooze * 60))
#time.sleep(snooze) # Sleep until next quarter hour.
else:
print('minutes:', minutes, ' no sleep')
import time
L = 15*60
while True:
#do something
#get current timestamp as an integer and round to the
#nearest larger or equal multiple of 15*60 seconds, i.e., 15 minutes
d = int(time.time())
m = d%L
sleepy_time = 0 if m == 0 else (L - m)
print(sleepy_time)
time.sleep(sleepy_time)
import schedule
import time
# Define a function named "job" to print a message
def job():
print("Job is running.")
# Set the interval for running the job function to 15 minutes
interval_minutes = 15
# Loop over the range of minutes with a step of interval_minutes
for minute in range(0, 60, interval_minutes):
# Format the time string to be in the format of "MM:SS"
time_string = f"{minute:02d}:00" if minute < 60 else "00:00"
# Schedule the job function to run at the specified time every hour
schedule.every().hour.at(time_string).do(job)
# Infinite loop to keep checking for any pending job
while True:
schedule.run_pending()
# Sleep for 1 second to avoid high CPU usage
time.sleep(1)
How do I sched a repeat timer for 5 min intervals. Which fire at 00 seconds, then repeat at 00. Ok, not hard real-time but as close as possible with sys lags. Trying to avoid a build up in lags and get near 00.
Lang: Python, OS: WinXP x64
System has 25ms resolution.
Any code would be helpful, tia
I don't know how to do it any more accurately than with threading.Timer. It's "one-shot", but that just means the function you schedule that way must immediately re-schedule itself for another 300 seconds later, first thing. (You can add accuracy by measuring the exact time with time.time each time and varying the next scheduling delay accordingly).
Try and compare the time printouts of these two code samples:
Code Sample 1
import time
delay = 5
while True:
now = time.time()
print time.strftime("%H:%M:%S", time.localtime(now))
# As you will observe, this will take about 2 seconds,
# making the loop iterate every 5 + 2 seconds or so.
## repeat 5000 times
for i in range(5000):
sum(range(10000))
# This will sleep for 5 more seconds
time.sleep(delay)
Code Sample 2
import time
delay = 5
while True:
now = time.time()
print time.strftime("%H:%M:%S", time.localtime(now))
# As you will observe, this will take about 2 seconds,
# but the loop will iterate every 5 seconds because code
# execution time was accounted for.
## repeat 5000 times
for i in range(5000):
sum(range(10000))
# This will sleep for as long as it takes to get to the
# next 5-second mark
time.sleep(delay - (time.time() - now))