A volte, su un computer di prova (Windows), il GC completo di Java richiede più di 20 secondi. I log del GC mostrano che il tempo dello real
è molto alto, user
è anche alto, ma non alto (circa 3 secondi). In un caso, è:Orologio da parete GC completo Java molto lento
21.2209796 secs [Times: user=3.76 sys=0.45, real=21.22 secs]
Quale potrebbe essere il motivo? Ho un sospetto ma non voglio dirlo adesso.
Qual è il modo più semplice per scoprire quale sia la causa principale? Se non conosci Windows ma conosci Linux, anche questa è un'opzione: i test potrebbero essere eseguiti su Linux.
Il processo è stato avviato come segue:
"%JAVA_HOME%\bin\java.exe" -verbose:gc -XX:+PrintGCDetails
-XX:+PrintGCDateStamps -Xloggc:publish.gc.log
-XX:PermSize=256m -XX:MaxPermSize=1024m -Xms1024m
-Xmx3072m -XX:NewSize=352m -XX:MaxNewSize=352m
-XX:SurvivorRatio=6
Non so il motivo per cui vengono utilizzati NewSize
, XX:MaxNewSize
e SurvivorRatio
. MaxPermSize
è necessario perché è un ambiente OSGi. I dump di thread completi non mostrano nulla di speciale.
il log completo della piena GC è (mi dispiace, lunga):
2014-05-06T21:38:18.735-0700: 150.261: [Full GC [PSYoungGen: 23614K->0K(309952K)] [PSOldGen: 693188K->311405K(688128K)] 716802K->311405K(998080K) [PSPermGen: 45120K->45120K(262144K)], 1.4533481 secs] [Times: user=1.45 sys=0.01, real=1.45 secs]
2014-05-06T21:38:58.379-0700: 189.907: [Full GC [PSYoungGen: 1664K->0K(335488K)] [PSOldGen: 668139K->283959K(688128K)] 669803K->283959K(1023616K) [PSPermGen: 46688K->46688K(262144K)], 1.3466773 secs] [Times: user=1.34 sys=0.00, real=1.35 secs]
2014-05-06T21:39:44.082-0700: 235.613: [Full GC [PSYoungGen: 15200K->0K(309184K)] [PSOldGen: 668643K->292329K(740800K)] 683843K->292329K(1049984K) [PSPermGen: 47733K->47733K(262144K)], 1.3649206 secs] [Times: user=1.36 sys=0.00, real=1.37 secs]
2014-05-06T21:40:33.090-0700: 284.623: [Full GC [PSYoungGen: 10132K->0K(326528K)] [PSOldGen: 718669K->308144K(858368K)] 728802K->308144K(1184896K) [PSPermGen: 49596K->43403K(262144K)], 1.2978991 secs] [Times: user=1.31 sys=0.02, real=1.30 secs]
2014-05-06T21:41:39.407-0700: 350.943: [Full GC [PSYoungGen: 37815K->0K(308160K)] [PSOldGen: 842013K->560237K(1236160K)] 879828K->560237K(1544320K) [PSPermGen: 43807K->43807K(262144K)], 1.2742777 secs] [Times: user=1.26 sys=0.00, real=1.27 secs]
2014-05-06T21:43:36.782-0700: 468.324: [Full GC [PSYoungGen: 640K->0K(329216K)] [PSOldGen: 1233468K->536017K(1242944K)] 1234108K->536017K(1572160K) [PSPermGen: 44438K->44438K(262144K)], 1.4105887 secs] [Times: user=1.42 sys=0.00, real=1.41 secs]
2014-05-06T21:44:28.404-0700: 519.948: [Full GC [PSYoungGen: 45056K->0K(315392K)] [PSOldGen: 1196082K->481770K(1266240K)] 1241138K->481770K(1581632K) [PSPermGen: 56883K->56883K(262144K)], 1.5773390 secs] [Times: user=1.58 sys=0.00, real=1.58 secs]
2014-05-06T21:44:51.101-0700: 542.646: [Full GC [PSYoungGen: 30000K->0K(315392K)] [PSOldGen: 1213653K->330467K(1129664K)] 1243653K->330467K(1445056K) [PSPermGen: 106752K->105936K(262144K)], 1.9804992 secs] [Times: user=1.97 sys=0.02, real=1.98 secs]
2014-05-06T21:45:33.230-0700: 584.777: [Full GC [PSYoungGen: 10301K->0K(319616K)] [PSOldGen: 1105014K->404683K(1248192K)] 1115315K->404683K(1567808K) [PSPermGen: 122771K->122771K(262144K)], 1.9884441 secs] [Times: user=2.00 sys=0.00, real=1.99 secs]
2014-05-06T21:46:24.169-0700: 635.719: [Full GC [PSYoungGen: 8805K->0K(331136K)] [PSOldGen: 1226188K->506891K(1449856K)] 1234994K->506891K(1780992K) [PSPermGen: 140233K->140233K(262144K)], 2.4515626 secs] [Times: user=2.45 sys=0.01, real=2.45 secs]
2014-05-06T21:47:34.131-0700: 705.683: [Full GC [PSYoungGen: 45054K->0K(315392K)] [PSOldGen: 1412337K->452967K(1474560K)] 1457392K->452967K(1789952K) [PSPermGen: 141009K->141009K(262144K)], 2.3155816 secs] [Times: user=2.31 sys=0.00, real=2.32 secs]
2014-05-06T21:48:17.036-0700: 748.590: [Full GC [PSYoungGen: 36896K->0K(315392K)] [PSOldGen: 1392671K->354862K(1476608K)] 1429567K->354862K(1792000K) [PSPermGen: 141037K->140960K(262144K)], 2.2993743 secs] [Times: user=2.28 sys=0.00, real=2.30 secs]
2014-05-06T21:49:23.816-0700: 815.374: [Full GC [PSYoungGen: 45036K->0K(315392K)] [PSOldGen: 1454959K->348537K(1509824K)] 1499995K->348537K(1825216K) [PSPermGen: 140963K->140963K(262144K)], 2.0907144 secs] [Times: user=2.09 sys=0.00, real=2.09 secs]
2014-05-06T22:04:38.728-0700: 1729.490: [Full GC [PSYoungGen: 8464K->0K(345344K)] [PSOldGen: 1505186K->422020K(1583296K)] 1513651K->422020K(1928640K) [PSPermGen: 151404K->151404K(262144K)], 3.2901866 secs] [Times: user=2.47 sys=0.00, real=3.31 secs]
2014-05-06T22:09:33.924-0700: 2023.858: [Full GC [PSYoungGen: 9766K->0K(342784K)] [PSOldGen: 1573919K->443383K(1656064K)] 1583686K->443383K(1998848K) [PSPermGen: 168657K->168657K(262144K)], 2.8910659 secs] [Times: user=2.59 sys=0.02, real=2.90 secs]
2014-05-06T22:16:32.650-0700: 2442.188: [Full GC [PSYoungGen: 5856K->0K(346944K)] [PSOldGen: 1650623K->398157K(1666944K)] 1656479K->398157K(2013888K) [PSPermGen: 176960K->153660K(262144K)], 5.6906733 secs] [Times: user=2.89 sys=0.11, real=5.69 secs]
2014-05-06T22:32:40.071-0700: 3409.496: [Full GC [PSYoungGen: 8566K->0K(346304K)] [PSOldGen: 1655315K->460797K(1767360K)] 1663882K->460797K(2113664K) [PSPermGen: 155265K->155265K(262144K)], 3.8090058 secs] [Times: user=2.81 sys=0.03, real=3.81 secs]
2014-05-06T22:37:53.667-0700: 3723.074: [Full GC [PSYoungGen: 10243K->0K(347456K)] [PSOldGen: 1761438K->458285K(1835712K)] 1771681K->458285K(2183168K) [PSPermGen: 162919K->162919K(262144K)], 4.0235684 secs] [Times: user=2.47 sys=0.06, real=4.02 secs]
2014-05-06T22:49:53.387-0700: 4442.757: [Full GC [PSYoungGen: 6441K->0K(348224K)] [PSOldGen: 1823902K->451504K(1872448K)] 1830344K->451504K(2220672K) [PSPermGen: 171778K->171778K(262144K)], 2.7130221 secs] [Times: user=2.62 sys=0.02, real=2.71 secs]
2014-05-06T22:59:59.750-0700: 5049.088: [Full GC [PSYoungGen: 6708K->0K(347904K)] [PSOldGen: 1862823K->365106K(1845248K)] 1869532K->365106K(2193152K) [PSPermGen: 180349K->154273K(262144K)], 9.6984956 secs] [Times: user=2.74 sys=0.16, real=9.70 secs]
2014-05-06T23:10:35.103-0700: 5684.407: [Full GC [PSYoungGen: 7984K->0K(352192K)] [PSOldGen: 1843448K->585793K(2170304K)] 1851433K->585793K(2522496K) [PSPermGen: 160183K->160183K(262144K)], 2.9633020 secs] [Times: user=2.93 sys=0.00, real=2.96 secs]
2014-05-06T23:24:38.972-0700: 6528.232: [Full GC [PSYoungGen: 7376K->0K(345344K)] [PSOldGen: 2159450K->684719K(2346304K)] 2166826K->684719K(2691648K) [PSPermGen: 164349K->164349K(262144K)], 8.8952964 secs] [Times: user=3.39 sys=0.05, real=8.90 secs]
2014-05-06T23:28:10.950-0700: 6740.198: [Full GC [PSYoungGen: 9085K->0K(346368K)] [PSOldGen: 2343205K->724235K(2458176K)] 2352290K->724235K(2804544K) [PSPermGen: 186771K->186771K(262144K)], 3.5238065 secs] [Times: user=3.29 sys=0.00, real=3.52 secs]
2014-05-06T23:33:58.654-0700: 7087.885: [Full GC [PSYoungGen: 9551K->0K(349184K)] [PSOldGen: 2453964K->597434K(2438976K)] 2463516K->597434K(2788160K) [PSPermGen: 205948K->166988K(262144K)], 12.9225761 secs] [Times: user=3.59 sys=0.12, real=12.92 secs]
2014-05-06T23:48:13.206-0700: 7942.391: [Full GC [PSYoungGen: 37116K->0K(313728K)] [PSOldGen: 2422753K->610864K(2500736K)] 2459870K->610864K(2814464K) [PSPermGen: 172487K->172487K(262144K)], 4.9881546 secs] [Times: user=3.28 sys=0.03, real=4.99 secs]
2014-05-07T00:06:19.018-0700: 9028.146: [Full GC [PSYoungGen: 8589K->0K(321920K)] [PSOldGen: 2492066K->620020K(2538304K)] 2500655K->620020K(2860224K) [PSPermGen: 179888K->179888K(262144K)], 3.5624930 secs] [Times: user=3.10 sys=0.06, real=3.56 secs]
2014-05-07T00:13:51.029-0700: 9480.134: [Full GC [PSYoungGen: 8736K->0K(330688K)] [PSOldGen: 2529168K->564197K(2540800K)] 2537904K->564197K(2871488K) [PSPermGen: 185765K->185765K(262144K)], 3.0340707 secs] [Times: user=2.95 sys=0.00, real=3.03 secs]
2014-05-07T00:25:39.758-0700: 10188.825: [Full GC [PSYoungGen: 17725K->0K(315392K)] [PSOldGen: 2500502K->543855K(2582528K)] 2518228K->543855K(2897920K) [PSPermGen: 190076K->167636K(262144K)], 12.3609341 secs] [Times: user=3.77 sys=0.16, real=12.36 secs]
2014-05-07T00:44:01.053-0700: 11290.063: [Full GC [PSYoungGen: 12896K->0K(347264K)] [PSOldGen: 2575016K->547199K(2621184K)] 2587912K->547199K(2968448K) [PSPermGen: 172447K->172447K(262144K)], 6.9150070 secs] [Times: user=3.15 sys=0.03, real=6.92 secs]
2014-05-07T01:41:59.932-0700: 14768.758: [Full GC [PSYoungGen: 23293K->0K(337152K)] [PSOldGen: 2638852K->580840K(2712704K)] 2662146K->580840K(3049856K) [PSPermGen: 175259K->175259K(262144K)], 11.0725751 secs] [Times: user=3.32 sys=0.13, real=11.07 secs]
2014-05-07T01:47:58.358-0700: 15127.165: [Full GC [PSYoungGen: 4176K->0K(315392K)] [PSOldGen: 2684820K->577513K(2738176K)] 2688996K->577513K(3053568K) [PSPermGen: 179064K->179064K(262144K)], 6.5166056 secs] [Times: user=3.01 sys=0.02, real=6.52 secs]
2014-05-07T01:55:50.842-0700: 15599.624: [Full GC [PSYoungGen: 18686K->0K(319616K)] [PSOldGen: 2735388K->490034K(2761664K)] 2754074K->490034K(3081280K) [PSPermGen: 182650K->169843K(262144K)], 21.2209796 secs] [Times: user=3.76 sys=0.45, real=21.22 secs]
2014-05-07T02:10:06.723-0700: 16455.460: [Full GC [PSYoungGen: 5561K->0K(321600K)] [PSOldGen: 2752252K->569179K(2785280K)] 2757813K->569179K(3106880K) [PSPermGen: 175120K->175120K(262144K)], 3.2125221 secs] [Times: user=3.15 sys=0.02, real=3.21 secs]
2014-05-07T02:22:36.759-0700: 17205.457: [Full GC [PSYoungGen: 16798K->0K(330304K)] [PSOldGen: 2775106K->580162K(2785280K)] 2791904K->580162K(3115584K) [PSPermGen: 181215K->181215K(262144K)], 3.1422615 secs] [Times: user=3.10 sys=0.02, real=3.14 secs]
2014-05-07T02:45:44.317-0700: 18592.941: [Full GC [PSYoungGen: 45049K->0K(315392K)] [PSOldGen: 2769893K->624026K(2785280K)] 2814943K->624026K(3100672K) [PSPermGen: 200552K->200552K(262144K)], 3.4347254 secs] [Times: user=3.29 sys=0.00, real=3.44 secs]
2014-05-07T03:08:18.628-0700: 19947.181: [Full GC [PSYoungGen: 5888K->0K(315392K)] [PSOldGen: 2783516K->419007K(2699456K)] 2789404K->419007K(3014848K) [PSPermGen: 218078K->169930K(262144K)], 11.5310136 secs] [Times: user=3.17 sys=0.20, real=11.53 secs]
2014-05-07T03:34:53.638-0700: 21542.106: [Full GC [PSYoungGen: 13636K->0K(315392K)] [PSOldGen: 2691667K->554781K(2785280K)] 2705303K->554781K(3100672K) [PSPermGen: 180174K->180174K(262144K)], 2.9612961 secs] [Times: user=2.95 sys=0.02, real=2.96 secs]
2014-05-07T03:48:06.871-0700: 22335.298: [Full GC [PSYoungGen: 45029K->0K(315392K)] [PSOldGen: 2757384K->645664K(2785280K)] 2802414K->645664K(3100672K) [PSPermGen: 191439K->191439K(262144K)], 4.0145124 secs] [Times: user=3.20 sys=0.05, real=4.01 secs]
2014-05-07T03:52:48.829-0700: 22617.241: [Full GC [PSYoungGen: 9744K->0K(315392K)] [PSOldGen: 2773296K->575320K(2785280K)] 2783041K->575320K(3100672K) [PSPermGen: 199506K->199506K(262144K)], 3.2600004 secs] [Times: user=3.20 sys=0.00, real=3.26 secs]
2014-05-07T03:57:47.110-0700: 22915.506: [Full GC [PSYoungGen: 10560K->0K(315392K)] [PSOldGen: 2771785K->436271K(2748608K)] 2782345K->436271K(3064000K) [PSPermGen: 215637K->170286K(262144K)], 6.1593551 secs] [Times: user=3.21 sys=0.05, real=6.16 secs]
2014-05-07T04:05:46.130-0700: 23394.501: [Full GC [PSYoungGen: 45046K->0K(315392K)] [PSOldGen: 2699071K->624303K(2785280K)] 2744117K->624303K(3100672K) [PSPermGen: 182442K->182442K(262144K)], 3.2887751 secs] [Times: user=3.25 sys=0.00, real=3.29 secs]
2014-05-07T04:09:00.646-0700: 23589.007: [Full GC [PSYoungGen: 45044K->0K(315392K)] [PSOldGen: 2716819K->709830K(2785280K)] 2761863K->709830K(3100672K) [PSPermGen: 187436K->187436K(262144K)], 3.4306116 secs] [Times: user=3.40 sys=0.00, real=3.43 secs]
L'heap JVM viene impaginato sul disco? Puoi provare a modificare il rapporto dei sopravvissuti? E potresti iniziare la JVM con '-XX: + PrintTenuringDistribution'? – hexafraction
Buone domande! Ma non posso rispondergli. Quale sarebbe il modo più semplice per scoprire se l'heap JVM viene impaginato sul disco? Potrei probabilmente modificare il rapporto dei sopravvissuti, ma come lo modificheresti e perché? –
Se l'heap JVM viene sfogliato in modo fasullo, in Task Manager di Windows, se lo si seleziona per mostrare le colonne "delta delle pagine di errore" e "errori di pagina" nella scheda Processi, si osserverebbero numeri relativamente grandi per entrambi. Il rapporto dei sopravvissuti può essere diminuito per impedire che l'overflow ritorni alla vecchia generazione o aumentato per evitare di spazzare uno spazio sopravvissuto quasi vuoto. Alcuni esperimenti possono aiutare in questo caso (provare 4 e 8 e confrontarli con 6). Immagino che il tempo del kernel sia alto, quindi c'è un po 'di paging o swapping (o potenzialmente un sacco di copie di grandi dimensioni facilitate dal kernel) – hexafraction