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deadlock
subject			fact

deadlock	can appear as a hung system where the system is not consuming CPU time
	has definition A failure in which two or more threads are stopped, waiting for each other to do something
	has example thread A is waiting to access object O object O is locked by thread B thread B, however might be waiting to access object P object P is locked by thread A Neither thread can ever progress unless some outside thread forces a break in the deadlock
	has example in real life gridlock
	is a subtopic of 10.5 - Defects in Timing and Co-Ordination: Deadlock, Livelocks and Critical Races
	is a kind of deadlock or livelock
	may not hang a system
deadlock or livelock	can be caused by over-use of locking
	can be detected by glass-box testing since you can actually study the progress and states of the various threads
	has black-box testing strategy Vary the time consumption of different threads by giving them differing amounts of input, or running them on hardware that varies in speed Run a large number of threads concurrently Deliberately deny resources to one or more threads (e.g. temporarily cut a network connection, or make a file unreadable)
	has testing strategy inspecting to detect such defects, rather than testing alone
	may occur as a result of unusual combinations of conditions that are hard to anticipate or reproduce
	should be tested for by a person with a background in real-time systems who can apply his or her knowledge and experience to best anticipate typical defects
failure	can be the result of a violation of an implicit requirement
	is usually the result of a violation of those requirements that are stated explicitly in a requirements document
	may arise from violations of either functional requirements or non-functional requirements
problem	has solution which will normally entail developing software, although you may decide that it is better to purchase software or to develop a non-software solution
	should be written as a simple problem statement in one or two sentences

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