Actionable Exceptions

Avishai Ish-Shalom (@nukemberg)

Exceptions are normal

"Normal exception"

By definition, exceptions are not normal

• Business errors
• System errors
• Exceptions

Either you thought it could happen, or you didn't

Exceptions are

events

Exceptions are designed to crash & burn

• Crash your thread
• Crash your program
• Inconsistent state

# cv = threading.Condition()
cv.acquire()
worker = Worker()
logger.debug("Starting work")

try:
    worker.do_something()
finally:
    cv.notify_all()

Spot the bug

Like "goto" but worse

• Can be thrown from anywhere
• Hard to track
• Hard to cleanup resources
• Heavyweight, slow

Exception are abused

Exceptions should be

Actionable

Every exception should result in a code or infrastructure change

If it's not

actionable,

It's

noise