When daemon will hog cpu?

What are the possible condition might occur for daemon to hog the cpu 开发者_如何学编程and makes the system very slow or moved to non-responsive state?

Daemons have few threads as well.

A tiny fraction of reasons include:

• infinite loops in general
• low memory in general
• race conditions
• dead locks
• starvation
• spawning too many threads
• forking too much
• super low process priority
• infinite recursion
• algorithms of bad algorithmic complexity
• really slow operations on numbers
• something is repeated too often (e.g. a variable that is better calculated outside a loop which the compiler was unable to move out)
• cache-unfriendliness
• using sleep-like functions
• invoking slow functions
• running the daemon on a slow machine
• your are being DOS-attacked
• your machine is running out of electricity and tries to slow down
• your CPU has a bug
• your CPU has a hardware defect
• your CPU is running at too low voltage

These list items are not exclusive to each other. We really can't tell something more specific without more information.

a) a bug

b) a large job

Are you thinking of a particular daemon?

Slow, non-responsive systems are more normally caused by I/O contention than CPU usage, by the way. Install iotop to see what's hogging your disk.

You can also nice or renice programs to free up the system a bit.