seems not work well.

[jinchenx]

in one terminal run the script: from time import sleep for i in range(10000): print "in loop" sleep(2)

in another terminal run the: sudo lptrace -p PID_OF_ABOVE_SCRIPT

no output in the second terminal, could you help to take a look why? Thanks in advance.

[ajyoon]

I believe the reason is that lptrace only traces user defined functions, not built-in functions like print and sleep. When I modify your code, for instance, with an additional user-defined method, it traces that just fine:

from time import sleep

def some_func():
    pass

for i in range(10000):
    some_func()
    sleep(2)

Giving the following trace:

$ sudo ./venv/bin/lptrace -p 24772
some_func (tmp.py:3)

some_func (tmp.py:3)

etc...

[ajyoon]

Besides, in most use cases you wouldn't want to be tracing built-in functions, since it'd rapidly become almost impossible to sift through all the interpreter-level stuff going on under the hood

[jinchenx]

Yes, it works well with user defined functions. And I think it's very useful when debugging python codes sleeping in somewhere with unknown reasons. Thank you very much for your quick respond.

[khamidou]

@ajyoon Yup, you're correct – lptrace only traces user-defined functions. There actually is a hook in the Python interpreter to trace CPython built-ins, but as you said, it wouldn't be very helpful.