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https://github.com/jlumbroso/pyjdb
Python interface with Java debugger through JDB.
https://github.com/jlumbroso/pyjdb
cs-education java-debugger jdb pexpect
Last synced: 20 days ago
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Python interface with Java debugger through JDB.
- Host: GitHub
- URL: https://github.com/jlumbroso/pyjdb
- Owner: jlumbroso
- License: lgpl-3.0
- Created: 2019-08-20T03:07:39.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2021-03-25T23:07:01.000Z (over 3 years ago)
- Last Synced: 2024-11-19T14:35:48.325Z (about 1 month ago)
- Topics: cs-education, java-debugger, jdb, pexpect
- Language: Python
- Size: 61.5 KB
- Stars: 5
- Watchers: 2
- Forks: 1
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# pyjdb
Python interface with Java debugger through JDB.
## Overview
The `JdbProcess` uses `pexpect` to attach to a `jdb` process and record all the information that is obtained.
For each instruction, we record a dictionary of the following format:
```json
{
"return": 10000,
"thread": "main",
"class.method": "IterPower.iterPower()",
"method": "iterPower",
"line": 15,
"bci": 17,
"instruction": "return result;"
}
```
For each instruction, we can also obtain the dictionary of the current method's arguments, as well as all its local variables:
```python
({'base': 10, 'exp': 0}, {'result': 10000})
```
## Example
Let's assume that we have this Java file, `IterPower.java`:
```java
public class IterPower {
public static void main(String[] args) {
// ... parse arguments ...
System.out.println(iterPower(base, exp));
}
public static int iterPower(int base, int exp) {
int result = 1;
while (exp > 0) {
result *= base;
exp -= 1;
}
return result;
}
}
```
which has been compiled with debugging information, `javac -g IterPower.java`. The following is a Python snippet:
```python
import pyjdb
import itertools
p = pyjdb.JdbProcess("IterPower")
p.spawn("10 4")
variables = {}
while True:
# Try to make an additional step and retrieve local variables
result = None
try:
p.step()
result = p.locals()
except pyjdb.EOF:
break
if result is None:
continue
# Store the values of each variable
(args, locs) = result
for (var, val) in itertools.chain(args.items(), locs.items()):
variables[var] = variables.get(var, list())
variables[var].append(val)
variables_unique_values = {
var: list(set(vals)) for (var, vals) in variables.items()
}
print(variables_unique_values)
```
The snippet will output a trace of the variable values of this program through its execution:
```json
{"args": ["instance of java.lang.String[0] (id=495)"],
"base": [10],
"exp": [0, 1, 2, 3, 4],
"result": [1, 10, 100, 1000, 10000]}
```
## Inspiration
This project was inspired by a [talk by Elena Glassman](https://youtu.be/Pt-DMk1YRJ4) in which she shows how to cluster [different implementations of the same solution](http://eglassman.github.io/mit-phd-thesis/thesis-slides.html#/10) according to the trace of the internal variables. Her work, which includes [OverCode](http://eglassman.github.io/overcode/) and [foobaz](https://www.youtube.com/watch?v=4X94_2XEsrE), focuses on Python programs. At my home institution, we use Java in our introductory classes. The initial goal of this project was to apply Dr. Glassman's techniques to Java assignments.
## Related projects
There were several ambitious projects related to bringing a Java debugger to Python. These projects highlight how complex an undertaking it is to implement the actual JDWP protocol. This is why in this project, our approach has been to piggy-back on `jdb` so as to not need to reimplement protocol-level functionality.
- [csuter/pyjdb](https://github.com/csuter/pyjdb) (abandonned): A Python implementation of the JDWP specifications.
- [soulseekah/pyjdb](https://github.com/soulseekah/pyjdb) (abandonned): A `jdb` replacement with more user-friendly features.