Anomalous be
havior due to unexpected critical dependence on t
he relative timing of events. For example, if one process writes to a file w
hile anot
her is reading from t
he same location t
hen t
he data read may be t
he old contents, t
he new contents or some mixture of t
he two depending on t
he relative timing of t
he read and write operations. A common remedy in t
his kind of race condition is {file locking} a more cumbersome remedy is to reorganize t
he system suc
h t
hat a certain processes (running a
href="module.php?name=Lexikon&file=search&eid=1&query=daemon">daemon or t
he like) is t
he only process t
hat
has access to t
he file, and all ot
her processes t
hat need to access t
he data in t
hat file do so only via interprocess communication wit
h t
hat one process. As an example of a more subtle kind of race condition, consider a
href="module.php?name=Lexikon&file=search&eid=1&query=distributed">distributed href="module.php?name=Lexikon&file=search&eid=1&query=chat">chat href="module.php?name=Lexikon&file=search&eid=1&query=network">network like
href="module.php?name=Lexikon&file=search&eid=1&query=IRC">IRC, w
here a
href="module.php?name=Lexikon&file=search&eid=1&query=user">user is granted c
hannel-operator
href="module.php?name=Lexikon&file=search&eid=1&query=privileges">privileges in any c
hannel
he starts. If two users on different
href="module.php?name=Lexikon&file=search&eid=1&query=servers">servers, on different ends of t
he same network, try to start t
he same-named c
hannel at t
he same time, eac
h user' s respective server will grant c
hannel-operator privileges to eac
h user, since neit
her will yet
have received t
he ot
her' s signal t
hat t
hat c
hannel
has been started. In t
his case of a race condition, t
he "s
hared resource" is t
he conception of t
he
href="module.php?name=Lexikon&file=search&eid=1&query=state">state of t
he network (w
hat c
hannels exist, as well as w
hat users started t
hem and t
herefore
have w
hat privileges), w
hic
h eac
h server is free to c
hange as long as it signals t
he ot
her servers on t
he network about t
he c
hanges so t
hat t
hey can update t
heir conception of t
he state of t
he network.
however, t
he
href="module.php?name=Lexikon&file=search&eid=1&query=latency">latency across t
he network makes possible t
he kind of race condition described. In t
his case,
heading off race conditions by imposing a form of control over access to t
he s
hared resource -- say, appointing one server to be in c
harge of w
ho
holds w
hat privileges -- would mean turning t
he distributed network into a centralized one (at least for t
hat one part of t
he network operation). W
here t
his is not acceptable, t
he more pragmatic solution is to
have t
he system recognize w
hen a race condition
has occurred and to repair t
he ill effects. Race conditions also affect electronic circuits w
here t
he value output by a
href="module.php?name=Lexikon&file=search&eid=1&query=logic gate">logic gate depends on t
he exact timing of two or more input signals. For example, consider a two input AND gate fed wit
h a logic signal X on input A and its negation, NOT X, on input B. In t
heory, t
he output (X AND NOT X) s
hould never be
hig
h.
however, if c
hanges in t
he value of X take longer to propagate to input B t
han to input A t
hen w
hen X c
hanges from false to true, t
here will be a brief period during w
hic
h bot
h inputs are true, and so t
he gate' s output will also be true. If t
his output is fed to an edge-sensitive component suc
h as a counter or flip-flop t
hen t
he temporary effect ("
href="module.php?name=Lexikon&file=search&eid=1&query=glitch">glitch") will become permanent. (2002-08-03)
In addition suitable contents:
[ href="module.php?name=Lexikon&op=content&tid=31">2 ] [ href="module.php?name=Lexikon&op=content&tid=134">= ] [ href="module.php?name=Lexikon&op=content&tid=195">accept ] [ href="module.php?name=Lexikon&op=content&tid=262">ad ] [ href="module.php?name=Lexikon&op=content&tid=374">ae ] [ href="module.php?name=Lexikon&op=content&tid=383">af ] [ href="module.php?name=Lexikon&op=content&tid=396">ag ] [ href="module.php?name=Lexikon&op=content&tid=411">ai ] [ href="module.php?name=Lexikon&op=content&tid=433">al ] [ href="module.php?name=Lexikon&op=content&tid=544">am ] [ href="module.php?name=Lexikon&op=content&tid=592">an ] [ href="module.php?name=Lexikon&op=content&tid=603">AND ] [ href="module.php?name=Lexikon&op=content&tid=683">app ] [ href="module.php?name=Lexikon&op=content&tid=740">ar ] [ href="module.php?name=Lexikon&op=content&tid=743">arc ] [ href="module.php?name=Lexikon&op=content&tid=759">arg ] [ href="module.php?name=Lexikon&op=content&tid=800">as ] [ href="module.php?name=Lexikon&op=content&tid=894">at ] [ href="module.php?name=Lexikon&op=content&tid=996">av ] [ href="module.php?name=Lexikon&op=content&tid=1025">B ] [ href="module.php?name=Lexikon&op=content&tid=1026">b ] [ href="module.php?name=Lexikon&op=content&tid=1181">be ] [ href="module.php?name=Lexikon&op=content&tid=1444">bo ] [ href="module.php?name=Lexikon&op=content&tid=1501">bot ] [ href="module.php?name=Lexikon&op=content&tid=1535">br ] [ href="module.php?name=Lexikon&op=content&tid=1624">bt ] [ href="module.php?name=Lexikon&op=content&tid=1695">by ] [ href="module.php?name=Lexikon&op=content&tid=1708">C ] [ href="module.php?name=Lexikon&op=content&tid=1724">ca ] [ href="module.php?name=Lexikon&op=content&tid=1844">case ] [ href="module.php?name=Lexikon&op=content&tid=1863">cat ] [ href="module.php?name=Lexikon&op=content&tid=1896">cc ] [ href="module.php?name=Lexikon&op=content&tid=2001">ch ] [ href="module.php?name=Lexikon&op=content&tid=2010">channel ] [ href="module.php?name=Lexikon&op=content&tid=2018">char ] [ href="module.php?name=Lexikon&op=content&tid=2099">ci ] [ href="module.php?name=Lexikon&op=content&tid=2121">circuit ] [ href="module.php?name=Lexikon&op=content&tid=2136">ck ] [ href="module.php?name=Lexikon&op=content&tid=2247">co ] [ href="module.php?name=Lexikon&op=content&tid=2330">com ] [ href="module.php?name=Lexikon&op=content&tid=2457">component ] [ href="module.php?name=Lexikon&op=content&tid=2545">con ] [ href="module.php?name=Lexikon&op=content&tid=2606">cons ] [ href="module.php?name=Lexikon&op=content&tid=2656">control ] [ href="module.php?name=Lexikon&op=content&tid=2791">cr ] [ href="module.php?name=Lexikon&op=content&tid=2900">cu ] [ href="module.php?name=Lexikon&op=content&tid=2941">cy ] [ href="module.php?name=Lexikon&op=content&tid=2976">D ] [ href="module.php?name=Lexikon&op=content&tid=2984">daemon ] [ href="module.php?name=Lexikon&op=content&tid=3006">data ] [ href="module.php?name=Lexikon&op=content&tid=3096">date ] [ href="module.php?name=Lexikon&op=content&tid=3151">de ] [ href="module.php?name=Lexikon&op=content&tid=3371">diff ] [ href="module.php?name=Lexikon&op=content&tid=3436">ding ] [ href="module.php?name=Lexikon&op=content&tid=3565">do ] [ href="module.php?name=Lexikon&op=content&tid=3752">du ] [ href="module.php?name=Lexikon&op=content&tid=3865">ec ] [ href="module.php?name=Lexikon&op=content&tid=3896">ed ] [ href="module.php?name=Lexikon&op=content&tid=3929">ee ] [ href="module.php?name=Lexikon&op=content&tid=3946">eg ] [ href="module.php?name=Lexikon&op=content&tid=3953">eh ] [ href="module.php?name=Lexikon&op=content&tid=3986">electron ] [ href="module.php?name=Lexikon&op=content&tid=4148">er ] [ href="module.php?name=Lexikon&op=content&tid=4150">era ] [ href="module.php?name=Lexikon&op=content&tid=4171">es ] [ href="module.php?name=Lexikon&op=content&tid=4199">et ] [ href="module.php?name=Lexikon&op=content&tid=4250">event ] [ href="module.php?name=Lexikon&op=content&tid=4301">expect ] [ href="module.php?name=Lexikon&op=content&tid=4497">fi ] [ href="module.php?name=Lexikon&op=content&tid=4520">file ] [ href="module.php?name=Lexikon&op=content&tid=4651">flip-flop ] [ href="module.php?name=Lexikon&op=content&tid=4700">fo ] [ href="module.php?name=Lexikon&op=content&tid=4727">for ] [ href="module.php?name=Lexikon&op=content&tid=4828">fr ] [ href="module.php?name=Lexikon&op=content&tid=4859">free ] [ href="module.php?name=Lexikon&op=content&tid=4989">ga ] [ href="module.php?name=Lexikon&op=content&tid=5026">gate ] [ href="module.php?name=Lexikon&op=content&tid=5057">ge ] [ href="module.php?name=Lexikon&op=content&tid=5134">gh ] [ href="module.php?name=Lexikon&op=content&tid=5141">gi ] [ href="module.php?name=Lexikon&op=content&tid=5171">gl ] [ href="module.php?name=Lexikon&op=content&tid=5184">glitch ] [ href="module.php?name=Lexikon&op=content&tid=5200">gm ] [ href="module.php?name=Lexikon&op=content&tid=5205">gn ] [ href="module.php?name=Lexikon&op=content&tid=5291">gr ] [ href="module.php?name=Lexikon&op=content&tid=5434">h ] [ href="module.php?name=Lexikon&op=content&tid=5493">hang ] [ href="module.php?name=Lexikon&op=content&tid=5540">hat ] [ href="module.php?name=Lexikon&op=content&tid=5768">hr ] [ href="module.php?name=Lexikon&op=content&tid=5931">id ] [ href="module.php?name=Lexikon&op=content&tid=5956">ie ] [ href="module.php?name=Lexikon&op=content&tid=5986">iff ] [ href="module.php?name=Lexikon&op=content&tid=6013">il ] [ href="module.php?name=Lexikon&op=content&tid=6064">in ] [ href="module.php?name=Lexikon&op=content&tid=6068">inc ] [ href="module.php?name=Lexikon&op=content&tid=6165">input ] [ href="module.php?name=Lexikon&op=content&tid=6194">int ] [ href="module.php?name=Lexikon&op=content&tid=6413">io ] [ href="module.php?name=Lexikon&op=content&tid=6448">IR ] [ href="module.php?name=Lexikon&op=content&tid=6449">ir ] [ href="module.php?name=Lexikon&op=content&tid=6451">IRC ] [ href="module.php?name=Lexikon&op=content&tid=6482">is ] [ href="module.php?name=Lexikon&op=content&tid=6558">it ] [ href="module.php?name=Lexikon&op=content&tid=6789">ke ] [ href="module.php?name=Lexikon&op=content&tid=6822">ki ] [ href="module.php?name=Lexikon&op=content&tid=6918">la ] [ href="module.php?name=Lexikon&op=content&tid=6988">latency ] [ href="module.php?name=Lexikon&op=content&tid=7023">ld ] [ href="module.php?name=Lexikon&op=content&tid=7091">Lex ] [ href="module.php?name=Lexikon&op=content&tid=7107">li ] [ href="module.php?name=Lexikon&op=content&tid=7281">location ] [ href="module.php?name=Lexikon&op=content&tid=7309">logic gate ] [ href="module.php?name=Lexikon&op=content&tid=7399">ls ] [ href="module.php?name=Lexikon&op=content&tid=7415">lu ] [ href="module.php?name=Lexikon&op=content&tid=7441">ly ] [ href="module.php?name=Lexikon&op=content&tid=7463">ma ] [ href="module.php?name=Lexikon&op=content&tid=7582">man ] [ href="module.php?name=Lexikon&op=content&tid=8019">mm ] [ href="module.php?name=Lexikon&op=content&tid=8032">mo ] [ href="module.php?name=Lexikon&op=content&tid=8040">mod ] [ href="module.php?name=Lexikon&op=content&tid=8079">module ] [ href="module.php?name=Lexikon&op=content&tid=8167">mp ] [ href="module.php?name=Lexikon&op=content&tid=8258">mu ] [ href="module.php?name=Lexikon&op=content&tid=8384">N ] [ href="module.php?name=Lexikon&op=content&tid=8386">na ] [ href="module.php?name=Lexikon&op=content&tid=8397">named ] [ href="module.php?name=Lexikon&op=content&tid=8460">nc ] [ href="module.php?name=Lexikon&op=content&tid=8468">ND ] [ href="module.php?name=Lexikon&op=content&tid=8472">ne ] [ href="module.php?name=Lexikon&op=content&tid=8488">net ] [ href="module.php?name=Lexikon&op=content&tid=8533">network ] [ href="module.php?name=Lexikon&op=content&tid=8627">ng ] [ href="module.php?name=Lexikon&op=content&tid=8630">ni ] [ href="module.php?name=Lexikon&op=content&tid=8660">nl ] [ href="module.php?name=Lexikon&op=content&tid=8672">nn ] [ href="module.php?name=Lexikon&op=content&tid=8675">no ] [ href="module.php?name=Lexikon&op=content&tid=8728">NOT ] [ href="module.php?name=Lexikon&op=content&tid=8745">np ] [ href="module.php?name=Lexikon&op=content&tid=8760">ns ] [ href="module.php?name=Lexikon&op=content&tid=8820">O ] [ href="module.php?name=Lexikon&op=content&tid=8964">om ] [ href="module.php?name=Lexikon&op=content&tid=9014">op ] [ href="module.php?name=Lexikon&op=content&tid=9071">operator ] [ href="module.php?name=Lexikon&op=content&tid=9120">org ] [ href="module.php?name=Lexikon&op=content&tid=9160">OT ] [ href="module.php?name=Lexikon&op=content&tid=9176">output ] [ href="module.php?name=Lexikon&op=content&tid=9204">pa ] [ href="module.php?name=Lexikon&op=content&tid=9457">pe ] [ href="module.php?name=Lexikon&op=content&tid=9550">ph ] [ href="module.php?name=Lexikon&op=content&tid=9651">pl ] [ href="module.php?name=Lexikon&op=content&tid=9762">point ] [ href="module.php?name=Lexikon&op=content&tid=9908">pr ] [ href="module.php?name=Lexikon&op=content&tid=9911">pragma ] [ href="module.php?name=Lexikon&op=content&tid=9995">process ] [ href="module.php?name=Lexikon&op=content&tid=10144">pt ] [ href="module.php?name=Lexikon&op=content&tid=10253">query ] [ href="module.php?name=Lexikon&op=content&tid=10364">rc ] [ href="module.php?name=Lexikon&op=content&tid=10385">re ] [ href="module.php?name=Lexikon&op=content&tid=10767">ro ] [ href="module.php?name=Lexikon&op=content&tid=10887">ru ] [ href="module.php?name=Lexikon&op=content&tid=10892">run ] [ href="module.php?name=Lexikon&op=content&tid=10922">sa ] [ href="module.php?name=Lexikon&op=content&tid=10959">sam ] [ href="module.php?name=Lexikon&op=content&tid=10999">say ] [ href="module.php?name=Lexikon&op=content&tid=11010">sc ] [ href="module.php?name=Lexikon&op=content&tid=11150">se ] [ href="module.php?name=Lexikon&op=content&tid=11259">serve ] [ href="module.php?name=Lexikon&op=content&tid=11261">server ] [ href="module.php?name=Lexikon&op=content&tid=11266">servers ] [ href="module.php?name=Lexikon&op=content&tid=11314">sh ] [ href="module.php?name=Lexikon&op=content&tid=11324">shar ] [ href="module.php?name=Lexikon&op=content&tid=11376">si ] [ href="module.php?name=Lexikon&op=content&tid=11389">sig ] [ href="module.php?name=Lexikon&op=content&tid=11396">signal ] [ href="module.php?name=Lexikon&op=content&tid=11506">sit ] [ href="module.php?name=Lexikon&op=content&tid=11651">so ] [ href="module.php?name=Lexikon&op=content&tid=11725">solution ] [ href="module.php?name=Lexikon&op=content&tid=11745">source ] [ href="module.php?name=Lexikon&op=content&tid=11790">spec ] [ href="module.php?name=Lexikon&op=content&tid=11934">st ] [ href="module.php?name=Lexikon&op=content&tid=11990">state ] [ href="module.php?name=Lexikon&op=content&tid=12133">su ] [ href="module.php?name=Lexikon&op=content&tid=12246">sy ] [ href="module.php?name=Lexikon&op=content&tid=12312">system ] [ href="module.php?name=Lexikon&op=content&tid=12359">T ] [ href="module.php?name=Lexikon&op=content&tid=12369">table ] [ href="module.php?name=Lexikon&op=content&tid=12416">tar ] [ href="module.php?name=Lexikon&op=content&tid=12440">tc ] [ href="module.php?name=Lexikon&op=content&tid=12588">th ] [ href="module.php?name=Lexikon&op=content&tid=12602">theory ] [ href="module.php?name=Lexikon&op=content&tid=12721">to ] [ href="module.php?name=Lexikon&op=content&tid=12777">tp ] [ href="module.php?name=Lexikon&op=content&tid=12787">tr ] [ href="module.php?name=Lexikon&op=content&tid=12873">tron ] [ href="module.php?name=Lexikon&op=content&tid=12939">tw ] [ href="module.php?name=Lexikon&op=content&tid=13030">um ] [ href="module.php?name=Lexikon&op=content&tid=13146">up ] [ href="module.php?name=Lexikon&op=content&tid=13175">us ] [ href="module.php?name=Lexikon&op=content&tid=13188">user ] [ href="module.php?name=Lexikon&op=content&tid=13252">va ] [ href="module.php?name=Lexikon&op=content&tid=13260">value ] [ href="module.php?name=Lexikon&op=content&tid=13310">ve ] [ href="module.php?name=Lexikon&op=content&tid=13366">vi ] [ href="module.php?name=Lexikon&op=content&tid=13694">while ] [ href="module.php?name=Lexikon&op=content&tid=13864">write ] [ href="module.php?name=Lexikon&op=content&tid=13891">X ] [ href="module.php?name=Lexikon&op=content&tid=14042">ye ]