Bugtation No.99
Tuesday, August 4th, 2009To be is to crash and to be crashed.
- Dmitry Vostokov @ DumpAnalysis.org -
Archive for August 4th, 2009
Trace Analysis Patterns (Part 8)
Tuesday, August 4th, 2009Sometimes there are reported delays in application startup, session initialization, long response times and simply the absence of response. All these problems can be reflected in software traces showing sudden gaps in threads of activity. I call this pattern Discontinuity per analogy with continuous and discontinuous functions in mathematics. Here is an example I came upon recently and it will be covered fully in the forthcoming pattern cooperation case study spanning both memory dump and trace analysis. One process was reported to have a long period of CPU spiking calculation and a CDF trace was recorded. When we open it we see this periodic error:
N PID TID Time Message
[…]
326 2592 5476 08:17:18.823 OpenRegistry: Attempting to open [… Hive path …]
327 2592 5476 08:17:18.824 OpenRegistry: Failed: 2
[…]
However when looking for any discontinuities for the thread 5476 we see this gap of more than 7 minutes:
N PID TID Time Message
[...]
3395 2592 5476 08:17:19.608 OpenRegistry: Attempting to open [... Hive path ...]
3396 2592 5476 08:17:19.608 OpenRegistry: Failed: 2
3461 2592 5476 08:24:31.137 OpenRegistry: Attempting to open [… Hive path …]
3462 2592 5476 08:24:31.137 OpenRegistry: Failed: 2
[…]
Therefore we have 3 possibilities here:
1. The process twice did lengthy CPU spiking calculations involving registry access and was quiet between them.
2. Registry access belonged to some background activity and ceased for 7 minutes and during that time it had CPU spiking intensive calculation.
3. This discontinuity is irrelevant because either the calculation module was not selected for tracing or it simply doesn’t have relevant tracing statement coverage for the code that does calculation.
Stay tuned because this story will be unfolded in other patterns and in the final case study.
- Dmitry Vostokov @ TraceAnalysis.org -
More Practical Foundations Series
Tuesday, August 4th, 2009OpenTask plans to expand its Practical Foundations series and publish the following 2 books for the forthcoming Memory Dump Analysis Fundamentals certification (Unix track) being developed by Memory Analysis and Debugging Institute:
Linux, FreeBSD and Mac OS X Debugging: Practical Foundations (ISBN: 978-1906717773)
64-bit Linux, FreeBSD and Mac OS X Debugging: Practical Foundations (ISBN: 978-1906717780)
- Dmitry Vostokov @ DumpAnalysis.org -