A while back, I posted the “profiling” CommitStrip on[WayBack] Profiling – Jeroen Wiert Pluimers – Google+. Boy how did I not know that within a week, I bumped into a “laptop fan profiling” artefact.
A coworker noticed, that when starting a thread based equivalent of [WayBack] TTimer Class (which cannot be used in services as it depends on the VCL), then sometimes the laptop fans would spin up.
What basically happened was that for certain combinations of Enabled and Interval the Execute would loop burning 100% of one CPU core.
With 3 or more – sometimes 2 – of these threads active on a 4+4 core (4 are hyper-threaded), the processor fan would start to spin like madness.
Finding the solution was somewhat easy too:
- Process Explorer would show the thread IDs burning the most CPU cycles
- Delphi shows the Thread IDs in the Thread Status pane (if they are named, the ID is at the end of the name in parenthesis)
- At around Delphi 2010, you can Freeze or Thaw threads. This allows you to debug only a single thread by freezing all others.
Focussing on one thread, allowed a close inspection of the loop, quickly finding the actual cause and repairing it.
TTimer Thread
A similar and better class is at [WayBack] multithreading – TTimerThread – Threaded timer class – Code Review Stack Exchange, based on [WayBack] timer – Using VCL TTimer in Delphi console application – Stack Overflow.
The Wiert Corner - irregular stream of stuff 