Breakpoints

Definition: What Does Breakpoint Mean?

The Role of Breakpoints in Debugging

• Achieve better understanding of the code: Breakpoints allow you to witness the inner workings of your program. They provide insights into how variables and functions interact with one another.
• Investigate problems: If the software isn’t behaving as expected, you can set a breakpoint at the suspect part of the code, allowing you to examine the state of the program at that particular moment.

Python Breakpoints: A Closer Look

def add_numbers(x, y):
    sum = x + y
    breakpoint()
    return sum
print(add_numbers(5, 6))

Benefits: Why Use Breakpoints?

• Reliably investigate the internal states of a program
• Control the flow of execution
• Find logical errors in the program
• Test specific sections of code without waiting for the whole code to execute

Working with Common Breakpoints

Identifying Common Breakpoints

• Software Breakpoints: The most frequently and generally used ones, inserted at a particular line of code where you expect the program to halt.
• Hardware Breakpoints: Useful when the debugger does not have access to the source code, or the code cannot be stopped by software breakpoints.
• Conditional Breakpoints: They cause the program to stop based on a particular condition, allowing the program to continue its execution until certain criteria are met.
• Data Breakpoints: They are triggered when a specific value (in a variable, for instance) changes, especially useful when tracing variable modifications.
• Temporary Breakpoints: These breakpoints are automatically removed once hit by the debugger. They are particularly useful for troubleshooting issues detectable only during a particular instance.

Setting Breakpoints for Efficient Debugging

• At Suspicious Code Blocks: If you suspect a specific code block is causing the application to malfunction, set a breakpoint at the start of that block.
• At Recursive Functions: Recursive functions can often become complex and difficult to debug. Setting a breakpoint allows you to examine each stage of the recursion.
• Before Calls to External Resources: These can include API calls, database queries, file operations, etc. By setting a breakpoint before such calls, you can confirm whether the problem lies in your application or the external resource.
• After Changes to Critical Data: If certain variables or data structures critically affect the application's operation, set breakpoints immediately after these data points are altered.

Data Breakpoints: An Overview

Breakpoints Troubleshooting: Tackling Issues

Common Problems when Setting Breakpoints

• Non-functional Breakpoints: Sometimes, you might find that your breakpoints don't seem to halt the program execution. This can occur due to various reasons such as incorrect placement of the breakpoint, or problems with the debugging tool used.
• Hit Count not Incrementing: Most debuggers keep track of the number of times a breakpoint is triggered. If you find that this count is not incrementing, it might be due to the breakpoint being placed in a section of code that is not being executed.
• Breakpoints Ignored in Loops: If placed inside a loop, the debugger may ignore some breakpoints. This happens particularly with conditional breakpoints when the condition does not hold true.
• Exception Breakpoints not Triggered: Exception breakpoints are meant to halt program execution when a particular exception is thrown. They might not trigger if the exception occurs outside of the monitored context or if the exception is handled within the program.

Helpful Problem-Solving Techniques

• Setting Breakpoints Correctly: Place the breakpoints at the exact line where you expect the program to halt. Keep in mind that the code execution halts before the line where the breakpoint is set.
• Verifying Breakpoint Placement: If your breakpoints aren't getting triggered, check to make sure they're placed in a section of code that is indeed being executed.
• Using the Right Conditions: In case of conditional breakpoints, verify that the conditions you've set are correct and check whether they meet during program execution.
• Checking Exception Monitoring: When using exception breakpoints, ensure to set the debugger to halt execution when the exception is thrown and also to monitor the correct context.

Troubleshooting Breakpoints in Python

for i in range(10):
    if i==4:
        breakpoint()
    print(i)