database question - Thrashing - What Is?

Question

Whats Thrashing? Ive heard it mentioned a few times at work and dont want to ask... Probably a stupid question - any ideas?

Answer 1

Reading through those pages :

• MySQL + LARGE innodb = thrashing HDD
• Reduce thrashing or poor system performance

I arrived to that one : Disk Thrashing, which states (quoting)

On a system with Virtual Memory, pages of memory are read from and written to the swap file as necessary.
Disk Thrashing is when there is excessive paging, specifically when the I/O system is busy paging memory but the CPU is not fully utilized - generally if the system is unresponsive (i.e. slow) and there is lots of disk activity then the system is likely to be thrashing.

And, of course, you might want to take a look on the Thrash (computer science) page on wikipedia ;-)

Answer 2

lmgify? http://en.wikipedia.org/wiki/Thrash_%28computer_science%29

Answer 3

Thrashing

In computer science, thrash (verb) is the term used to describe a degenerate situation on a computer where increasing resources are used to do a decreasing amount of work. In this situation the system is said to be thrashing. Usually it refers to two or more processes accessing a shared resource repeatedly such that serious system performance degradation occurs because the system is spending a disproportionate amount of time just accessing the shared resource. Resource access time may generally be considered as wasted, since it does not contribute to the advancement of any process.

Answer 4

Thraching is where a process consumes all available resources without achieving anything useful. Examples are endless loops or code that retries a failed command endlessly.