Case Study
How We Traced a Long-Run Crash to a Handle Leak
Case-study page for a long-run crash that was narrowed into a handle-leak investigation through observation design and logging.
Case Overview
This case concerns a Windows app that crashed suddenly only after about one month of continuous operation. Starting from organizing the observation points, the work was ultimately narrowed to an investigation centered on a handle leak. The key point was that we decided not only on the cause itself but on which observations to put in place first.
Symptom
- It did not appear within a few days; it crashed only after long-running operation
- The way exceptions appeared did not make it easy to judge whether it was a leak
- It happened only on site, so reproduction had to be compressed on the development machine
Constraints
- Waiting a month for each reproduction was not realistic
- Because camera reconnection and failure paths were involved, normal-path logs alone were not enough
- Which resource was growing had to be observable continuously
What We Observed
- A heartbeat of
Handle Count,Private Bytes, andThread Count - Boundary logs for session start, reconnection, and shutdown
- Paired lifecycle logs for
create/open/registerandclose/dispose/unregister
How We Narrowed It Down
Rather than chasing the “long-run crash” as such, we first compressed the reproduction into the failure paths around reconnection and timeouts. As a result, we could judge that suspecting a handle leak rather than a memory leak was the better line, and concentrate the observation there.
How We Improved It
- Added monitoring items so the growth trend could be followed, not just the moment of the crash
- Organized the boundary logs so it was easier to follow which responsibility opened and which closed
- Organized the findings so they could feed into the subsequent failure-path test infrastructure
Services This Case Connects To
This case connects to both Bug Investigation & Root Cause Analysis, which isolates failures that appear only after long-running operation, and Windows App Development, which puts logging, reconnection, and operational observation in order from the implementation side.
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