Wait time in python

Python’s time.sleep() – Pause, Stop, Wait or Sleep your Python Code

Suppose you are developing a user interface, and you support it with your code. Your user is uploading a document, and your code needs to wait for the time the file is being uploaded. Also, when you visit a complex having automated doors, you must have noticed that while you are entering the complex, the door stands still. Only when you have entered the complex, the door closes automatically. What is causing the delay in both situations?

Codes support both systems discussed above. It is the time delay function of programming languages that is causing the required time delay. We can also add time delays in our Python codes. The time module of Python allows us to establish delay commands between two statements. There are numerous ways to add a time delay and, in this article, we will discuss each method step-by-step.

Python’s time.sleep() – Pause, Stop, Wait or Sleep your Python Code

Python’s time module has a handy function called sleep() . Essentially, as the name implies, it pauses your Python program. The time.sleep() command is the equivalent to the Bash shell’s sleep command. Almost all programming languages have this feature.

The time.sleep() function

While using this function, we can specify the delay, and the compiler will execute the fixed time delay. The syntax of this function is as follows:

time.sleep() Arguments

• secs — The number of seconds the Python program should pause execution. This argument should be either an int or float .

Using Python’s time.sleep()

Here’s a quick, simple example of the syntax:

Here we have instructed the system to wait for five seconds through the first command and then wait for three hundred milliseconds, which equals 0.3 seconds. You can note here that we have written the value of the time delay inside the bracket based on the syntax.

Now let us consider another example to execute time delay.

Here we have taken a variable ‘a’ whose value we have stored as five. Now we are printing the value ‘a’ and then again printing an increased value of ‘a’. However, there is a time delay between the execution of both statements. And, we have specified that using the time.sleep() function. You must have observed that we have also imported the time module at the beginning of the code.

Now let’s see what the output is:

Here we can see that only the first command is executed. Now the output after five seconds:

Now, after a delay of five seconds, the second statement is also executed.

Advanced syntax of the sleep() function

Here’s a more advanced example. It takes user input and asks you how long you want to sleep() . It also proves how it works by printing out the timestamp before and after the time.sleep() call. Note that Python 2.x uses the raw_input() function to get user input, whereas Python 3.x uses the input() function. Now let us see the input syntax:

The code given above asks the user how long to wait. We have mentioned the command for this output in the sleeper() function. Then, the code prints the computer time at the beginning of the execution of code and after the implementation of code. This way, we get to see the actual functioning of the delay function. Now let’s see the output:

The system asks for our input, i.e., how long we want the system to wait. Let’s enter 5 seconds and observe the final output.

We can see that the starting computer time(“Before”) and ending computer time(“After”) have a time difference of five seconds.

The Accuracy of time.sleep()

The time.sleep() function uses the underlying operating system’s sleep() function. Ultimately there are limitations of this function. For example, on a standard Windows installation, the smallest interval you may delay is 10 — 13 milliseconds. The Linux kernels tend to have a higher tick rate, where the intervals are generally closer to 1 millisecond. Note that in Linux, you can install the RT_PREEMPT patch set, which allows you to have a semi-realtime kernel. Using a real-time kernel will further increase the accuracy of the time.sleep() function. However, unless you want to sleep for a brief period, you can generally ignore this information.

Using Decorators To Add time.sleep() Command

Decorators are used for creating simple syntax for calling higher-order functions. When can we use decorators? Suppose we have to test a function again, or the user has to download a file again, or you have to check the status of an interface after a specific time interval. You require a time delay between the first attempt and the second attempt. Thus, you can use decorators in cases where you need to check repeatedly and require a time delay.

Let’s consider an example using decorators. In this program, we will calculate the amount of time taken for the execution of the function.

Here time_calc() is the decorator function extending and containing the other functions, thus providing a simple syntax. Let’s see what we get as the output.

Using Threads To Add time.sleep() Command

Multiple-threading in Python is equivalent to running several programs simultaneously. When multi-threading is combined with the time module, we can solve complex problems quickly. Multi-threading functions are available from the threading module.

Let’s print the alphabet song using multi-threading and time delay.

Here one thread is being used to print the individual alphabets. There is a time delay of 0.5 seconds as well. When you run the program, you will see that each line of the alphabet song is printed after a delay of 0.5 seconds. Let’s see what the output is:

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Python wait time, wait for user input

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Sometimes we want our python program to wait for a specific time before executing the next steps. We can use time module sleep() function to pause our program for specified seconds.

Python wait time

Let’s see a quick example where we will pause our program for 5 seconds before executing further statements.

import time print('Hello There, next message will be printed after 5 seconds.') time.sleep(5) print('Sleep time is over.') 

When we run this program, there will be 5 seconds delay between first print statement and second print statement.

Python wait for user input

Sometimes we want to get some inputs from the user through the console. We can use input() function to achieve this. In this case, the program will wait indefinitely for the user input. Once the user provides the input data and presses the enter key, the program will start executing the next statements.

sec = input('Let us wait for user input. Let me know how many seconds to sleep now.\n') print('Going to sleep for', sec, 'seconds.') time.sleep(int(sec)) print('Enough of sleeping, I Quit!') 

Below short screen capture shows the complete program execution. Surprising, there is no easy way to wait for user input with a timeout or default value when empty user input is provided. I hope these useful features come in future Python releases.

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How to Wait in Python

Multiple operations happen simultaneously in an application to give the user a seamless browsing experience. However, some operations must be paused until an external condition is met, either on the user or server side. The ongoing operation is delayed for a moment until the external condition is met. So programmers who foresaw this eventuality in advance would tweak the program, such as directing it to wait until a specified time. Today, we will go through the wait() function and other methods in Python that are used to tell a computer to wait until a condition is met.

What is Wait in Python?

Though there are a plethora of ways to make a pause in Python the most prevalent way is to use the wait() function.

The wait() method in Python is used to make a running process wait for another function to complete its execution, such as a child process, before having to return to the parent class or event. This wait() method in Python is an os module method that synchronises the parent and child processes, implying that the parent will stand in line for the child process to complete its execution, i.e., wait until the child process ends before continuing with its process execution.

The wait() method is known as a method of the event class in the Python threading module to release the execution of an event when its internal flag is set to false, which will cause the current block or event to be released until the internal flag is set to true.

The wait() function is called os.wait() in Python, and its syntax is as follows:

This syntax returns the id of the child process as a tuple, coupled with a 16-bit number that also appears in the tuple to indicate the exit status. This method returns a 16-bit integer with higher and lower bytes, where the lower byte is represented by the signal number zero, which ends the process, and the higher byte contains the exit status notice. There are no parameters or arguments for the os.wait() function.

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