Running¶
Running, restarting, or stopping the program.
When a program is stopped there are several possibilities for further program execution. You can:
terminate the program inside the debugger
restart the program
continue its execution until it would normally terminate or until a breakpoint is hit
step exection which is runs for a limited amount of code before stopping
About debugging overhead¶
Explain¶
When you enable the debugger, it adds overhead and slows down your program. The overhead is greater than pdb, because the debugger tries to analyze the program in depth. In most cases, this does not diminish the debugging experience. But for some instructions, the overhead can be very large. For example, if you turn on the debugger and run the `import pandas` instruction, it can increase your CPU to 100% for a while.
$ cat tmp.py
#!/usr/bin/env python3
import pandas as pd
$ trepan3k tmp.py
(trepan3k) next # that increase your CPU to 100% for a while
The debugger overhead only concerns the instructions of the program to be debugged, the instructions of the trepan3k interpreter are not analyzed, so there is no overhead. For example, in trepan3k, do an `import pandas` and you will probably see that things are instantaneous.
$ trepan3k tmp.py
(trepan3k) import pandas as pd # that things are instantaneous
Technique to reduce the overhead costs¶
Activate the debugger only when you need it
Look at https://python3-trepan.readthedocs.io/en/latest/entry-exit.html#calling-the-debugger-from-your-program. By doing there is no slowdown whatsoever until the first breakpoint is hit.
Use debugging commands with less overhead
Not all commands have the same overhead.
Setting a breakpoint and running “continue” is faster than `next` command. Because `next` tries to be more accurate about nexting and that considerably slows things down.