Java Reference
In-Depth Information
Thisapplicationletsmoremoneybewithdrawnthanisavailableintheaccount.For
example,thefollowingoutputreveals$110beingwithdrawnwhenonly$100isavail-
able:
Wife withdraws $10: true
Wife withdraws $10: true
Husband withdraws $10: true
Wife withdraws $10: true
Husband withdraws $10: true
Wife withdraws $10: true
Husband withdraws $10: true
Husband withdraws $10: true
Husband withdraws $10: true
Husband withdraws $10: true
Husband withdraws $10: false
Husband withdraws $10: false
Husband withdraws $10: false
Husband withdraws $10: false
Wife withdraws $10: true
Wife withdraws $10: false
Wife withdraws $10: false
Wife withdraws $10: false
Wife withdraws $10: false
Wife withdraws $10: false
Thereasonwhymoremoneyiswithdrawnthanisavailableforwithdrawalisthata
race condition exists between the husband and wife threads.
Note
A
race condition
isascenarioinwhichmultiplethreadsupdatethesameobject
atthesametimeornearlyatthesametime.Partoftheobjectstoresvalueswrittento
it by one thread, and another part of the object stores values written to it by another
thread.
Theraceconditionexistsbecausetheactionsofcheckingtheamountforwithdrawal
toensurethatitislessthanwhatappearsinthebalanceanddeductingtheamountfrom
thebalancearenot
atomic
(indivisible)operations.(Althoughatomsaredivisible,
atom-
ic
is commonly used to refer to something being indivisible.)
Note
The
Thread.sleep()
methodcallthatsleepsforavariableamountoftime
(uptoamaximumof199milliseconds)ispresentsothatyoucanobservemoremoney
