<< Back to posts
Helpful PDB Commands
pdb is Python’s built-in interactive debugger. Here is a list of helpful pdb commands to debug Python programs.
Automatically break at error
This is literally a cheatcode for debugging Python programs.
If you run your python program by prefixing -m pdb , it will automatically set a breakpoint + open a debugging session whenever an uncaught exception occurs.
python3 -m pdb script.py
PDB Commands
Within a pdb session…
Visibility
l: Show lines before/after current breakpoint
Command: l (“list”)
Example:
> /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/finetune.py(202)main()
-> logits: Float[torch.Tensor, 'B L C'] = model(**batch)
(Pdb) l
198 print(t)
199 raise e
200
201 # Run model
202 -> logits: Float[torch.Tensor, 'B L C'] = model(**batch)
203
204 # Compute CE loss
205 binary_labels = torch.tensor(values, device=args.device).long()
206 loss = criterion(logits, binary_labels)
w: Print stack trace
Command: w (“where”)
Example:
(Pdb) w
/share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/finetune.py(220)<module>()
-> main()
> /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/finetune.py(202)main()
-> logits: Float[torch.Tensor, 'B L C'] = model(**batch)
u: Go up one level of stack trace
Command: u (“up”)
Example:
(Pdb) w
/share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/finetune.py(220)<module>()
-> main()
> /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/finetune.py(202)main()
-> logits: Float[torch.Tensor, 'B L C'] = model(**batch)
(Pdb) u
> /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/finetune.py(220)<module>()
-> main()
d: Go down one level of stack trace
Command: d (“down”)
Example:
(Pdb) w
> /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/finetune.py(220)<module>()
-> main()
/share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/finetune.py(202)main()
-> logits: Float[torch.Tensor, 'B L C'] = model(**batch)
(Pdb) d
> /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/finetune.py(202)main()
-> logits: Float[torch.Tensor, 'B L C'] = model(**batch)
Running Code
n: Advance to next line
Command: n (“next”)
Example:
(Pdb) l
198 print(t)
199 raise e
200
201 # Run model
202 -> logits: Float[torch.Tensor, 'B L C'] = model(**batch)
203
204 # Compute CE loss
205 binary_labels = torch.tensor(values, device=args.device).long()
206 loss = criterion(logits, binary_labels)
207
(Pdb) n
> /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/finetune.py(206)main()
-> binary_labels = torch.tensor(values, device=args.device).long()
(Pdb) l
201 # Run model
202 logits: Float[torch.Tensor, 'B L C'] = model(**batch)
203
204 # Compute CE loss
205 -> binary_labels = torch.tensor(values, device=args.device).long()
206 loss = criterion(logits, binary_labels)
207
208 # Backward pass and optimization step
209 optimizer.zero_grad()
210 loss.backward()
c: Continue until next breakpoint
Command: c (“continue”)
Example:
(Pdb) l
198 print(t)
199 raise e
200
201 # Run model
202 breakpoint()
203 -> logits: Float[torch.Tensor, 'B C'] = model(**batch)
204
205 # Compute CE loss
206 binary_labels: Float[torch.Tensor, 'B'] = torch.tensor(values, device=args.device).long()
207 loss = criterion(logits, binary_labels)
208
(Pdb) c
> /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/finetune.py(211)main()
-> optimizer.zero_grad()
(Pdb) l
206 binary_labels: Float[torch.Tensor, 'B'] = torch.tensor(values, device=args.device).long()
207 loss = criterion(logits, binary_labels)
208
209 # Backward pass and optimization step
210 breakpoint()
211 -> optimizer.zero_grad()
212 loss.backward()
213 optimizer.step()
214
215 # Save the fine-tuned model
216 save_finetuned_model(model)
Breakpoints
b [LINE_NUM]: Add breakpoint to line #LINE_NUM
Command: b [LINE_NUM] (“break”)
Example:
(Pdb) b 200
Breakpoint 4 at /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/ehrshot.py:200
(Pdb) break
Num Type Disp Enb Where
4 breakpoint keep yes at /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/ehrshot.py:200
break: Print out all active breakpoints
Command: break (“breakpoints”)
Example:
(Pdb) break
Num Type Disp Enb Where
1 breakpoint keep yes at /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/ehrshot.py:200
clear [B_NUM]: Deletes breakpoint #B_NUM
Command: clear [B_NUM] (“clear”)
Example:
(Pdb) break
Num Type Disp Enb Where
5 breakpoint keep yes at /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/ehrshot.py:200
6 breakpoint keep yes at /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/ehrshot.py:201
(Pdb) clear 5
Deleted breakpoint 5 at /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/ehrshot.py:200
(Pdb) break
Num Type Disp Enb Where
6 breakpoint keep yes at /share/pi/nigam/mwornow/hf_ehr/hf_ehr/eval/ehrshot.py:201