Level 5: Debug A Lightning app¶
Audience: Users who want to debug a distributed app locally.
Prereqs: You must have finished the Basic levels.
Enable breakpoints¶
To enable a breakpoint, use set_trace() (note direct python pdb support is work in progress and open to contributions).
Toy app
Add a breakpoint. When the program runs, it will stop at this line.
# app.py
from lightning.app import LightningWork, LightningFlow, LightningApp
class Component(LightningWork):
def run(self, x):
print(x)
class WorkflowOrchestrator(LightningFlow):
def __init__(self) -> None:
super().__init__()
self.component = Component()
def run(self):
self.component.run('i love Lightning')
app = LightningApp(WorkflowOrchestrator())
# app.py
from lightning.app import LightningWork, LightningFlow, LightningApp
from lightning.app.pdb import set_trace
class Component(LightningWork):
def run(self, x):
print(x)
set_trace()
class WorkflowOrchestrator(LightningFlow):
def __init__(self) -> None:
super().__init__()
self.component = Component()
def run(self):
self.component.run('i love Lightning')
app = LightningApp(WorkflowOrchestrator())
Next: Run a component in parallel¶
Learn to run components in parallel to enable more powerful workflows.
