{"id":1022,"date":"2018-09-07T10:29:16","date_gmt":"2018-09-07T02:29:16","guid":{"rendered":"https:\/\/blog.jsjs.org\/?p=1022"},"modified":"2018-09-07T10:29:16","modified_gmt":"2018-09-07T02:29:16","slug":"java-jvm-%e5%8f%82%e6%95%b0-xms-xmx-xmn-xss-%e8%b0%83%e4%bc%98%e6%80%bb%e7%bb%93","status":"publish","type":"post","link":"https:\/\/blog.jsjs.org\/?p=1022","title":{"rendered":"java jvm \u53c2\u6570 -Xms -Xmx -Xmn -Xss \u8c03\u4f18\u603b\u7ed3"},"content":{"rendered":"

\u5e38\u89c1\u914d\u7f6e\u4e3e\u4f8b\u00a0<\/strong>
\n\u5806\u5927\u5c0f\u8bbe\u7f6e
\nJVM \u4e2d\u6700\u5927\u5806\u5927\u5c0f\u6709\u4e09\u65b9\u9762\u9650\u5236:\u76f8\u5173\u64cd\u4f5c\u7cfb\u7edf\u7684\u6570\u636e\u6a21\u578b(32-bt\u8fd8\u662f64-bit)\u9650\u5236;\u7cfb\u7edf\u7684\u53ef\u7528\u865a\u62df\u5185\u5b58\u9650\u5236;\u7cfb\u7edf\u7684\u53ef\u7528\u7269\u7406\u5185\u5b58\u9650\u5236.32\u4f4d\u7cfb\u7edf \u4e0b,\u4e00\u822c\u9650\u5236\u57281.5G~2G;64\u4e3a\u64cd\u4f5c\u7cfb\u7edf\u5bf9\u5185\u5b58\u65e0\u9650\u5236.\u6211\u5728Windows Server 2003 \u7cfb\u7edf,3.5G\u7269\u7406\u5185\u5b58,JDK5.0\u4e0b\u6d4b\u8bd5,\u6700\u5927\u53ef\u8bbe\u7f6e\u4e3a1478m.
\n\u5178\u578b\u8bbe\u7f6e:
\njava -Xmx3550m -Xms3550m -Xmn2g -Xss128k
\n-Xmx3550m:\u8bbe\u7f6eJVM\u6700\u5927\u53ef\u7528\u5185\u5b58\u4e3a3550M.
\n-Xms3550m:\u8bbe\u7f6eJVM\u4fc3\u4f7f\u5185\u5b58\u4e3a3550m.\u6b64\u503c\u53ef\u4ee5\u8bbe\u7f6e\u4e0e-Xmx\u76f8\u540c,\u4ee5\u907f\u514d\u6bcf\u6b21\u5783\u573e\u56de\u6536\u5b8c\u6210\u540eJVM\u91cd\u65b0\u5206\u914d\u5185\u5b58.
\n-Xmn2g:\u8bbe\u7f6e\u5e74\u8f7b\u4ee3\u5927\u5c0f\u4e3a2G.\u6574\u4e2a\u5806\u5927\u5c0f=\u5e74\u8f7b\u4ee3\u5927\u5c0f + \u5e74\u8001\u4ee3\u5927\u5c0f + \u6301\u4e45\u4ee3\u5927\u5c0f.\u6301\u4e45\u4ee3\u4e00\u822c\u56fa\u5b9a\u5927\u5c0f\u4e3a64m,\u6240\u4ee5\u589e\u5927\u5e74\u8f7b\u4ee3\u540e,\u5c06\u4f1a\u51cf\u5c0f\u5e74\u8001\u4ee3\u5927\u5c0f.\u6b64\u503c\u5bf9\u7cfb\u7edf\u6027\u80fd\u5f71\u54cd\u8f83\u5927,Sun\u5b98\u65b9\u63a8\u8350\u914d\u7f6e\u4e3a\u6574\u4e2a\u5806\u76843\/8.
\n-Xss128k: \u8bbe\u7f6e\u6bcf\u4e2a\u7ebf\u7a0b\u7684\u5806\u6808\u5927\u5c0f.JDK5.0\u4ee5\u540e\u6bcf\u4e2a\u7ebf\u7a0b\u5806\u6808\u5927\u5c0f\u4e3a1M,\u4ee5\u524d\u6bcf\u4e2a\u7ebf\u7a0b\u5806\u6808\u5927\u5c0f\u4e3a256K.\u66f4\u5177\u5e94\u7528\u7684\u7ebf\u7a0b\u6240\u9700\u5185\u5b58\u5927\u5c0f\u8fdb\u884c \u8c03\u6574.\u5728\u76f8\u540c\u7269\u7406\u5185\u5b58\u4e0b,\u51cf\u5c0f\u8fd9\u4e2a\u503c\u80fd\u751f\u6210\u66f4\u591a\u7684\u7ebf\u7a0b.\u4f46\u662f\u64cd\u4f5c\u7cfb\u7edf\u5bf9\u4e00\u4e2a\u8fdb\u7a0b\u5185\u7684\u7ebf\u7a0b\u6570\u8fd8\u662f\u6709\u9650\u5236\u7684,\u4e0d\u80fd\u65e0\u9650\u751f\u6210,\u7ecf\u9a8c\u503c\u57283000~5000\u5de6\u53f3.<\/p>\n

java -Xmx3550m -Xms3550m -Xss128k -XX:NewRatio=4 -XX:SurvivorRatio=4 -XX:MaxPermSize=16m -XX:MaxTenuringThreshold=0
\n-XX:NewRatio=4:\u8bbe\u7f6e\u5e74\u8f7b\u4ee3(\u5305\u62ecEden\u548c\u4e24\u4e2aSurvivor\u533a)\u4e0e\u5e74\u8001\u4ee3\u7684\u6bd4\u503c(\u9664\u53bb\u6301\u4e45\u4ee3).\u8bbe\u7f6e\u4e3a4,\u5219\u5e74\u8f7b\u4ee3\u4e0e\u5e74\u8001\u4ee3\u6240\u5360\u6bd4\u503c\u4e3a1:4,\u5e74\u8f7b\u4ee3\u5360\u6574\u4e2a\u5806\u6808\u76841\/5
\n-XX:SurvivorRatio=4:\u8bbe\u7f6e\u5e74\u8f7b\u4ee3\u4e2dEden\u533a\u4e0eSurvivor\u533a\u7684\u5927\u5c0f\u6bd4\u503c.\u8bbe\u7f6e\u4e3a4,\u5219\u4e24\u4e2aSurvivor\u533a\u4e0e\u4e00\u4e2aEden\u533a\u7684\u6bd4\u503c\u4e3a2:4,\u4e00\u4e2aSurvivor\u533a\u5360\u6574\u4e2a\u5e74\u8f7b\u4ee3\u76841\/6
\n-XX:MaxPermSize=16m:\u8bbe\u7f6e\u6301\u4e45\u4ee3\u5927\u5c0f\u4e3a16m.
\n-XX:MaxTenuringThreshold=0: \u8bbe\u7f6e\u5783\u573e\u6700\u5927\u5e74\u9f84.\u5982\u679c\u8bbe\u7f6e\u4e3a0\u7684\u8bdd,\u5219\u5e74\u8f7b\u4ee3\u5bf9\u8c61\u4e0d\u7ecf\u8fc7Survivor\u533a,\u76f4\u63a5\u8fdb\u5165\u5e74\u8001\u4ee3. \u5bf9\u4e8e\u5e74\u8001\u4ee3\u6bd4\u8f83\u591a\u7684\u5e94\u7528,\u53ef\u4ee5\u63d0\u9ad8\u6548\u7387.\u5982\u679c\u5c06\u6b64\u503c\u8bbe\u7f6e\u4e3a\u4e00\u4e2a\u8f83\u5927\u503c,\u5219\u5e74\u8f7b\u4ee3\u5bf9\u8c61\u4f1a\u5728Survivor\u533a\u8fdb\u884c\u591a\u6b21\u590d\u5236,\u8fd9\u6837\u53ef\u4ee5\u589e\u52a0\u5bf9\u8c61\u518d\u5e74\u8f7b\u4ee3\u7684\u5b58\u6d3b \u65f6\u95f4,\u589e\u52a0\u5728\u5e74\u8f7b\u4ee3\u5373\u88ab\u56de\u6536\u7684\u6982\u8bba.
\n\u56de\u6536\u5668\u9009\u62e9
\nJVM\u7ed9\u4e86\u4e09\u79cd\u9009\u62e9:\u4e32\u884c\u6536\u96c6\u5668,\u5e76\u884c\u6536\u96c6\u5668,\u5e76\u53d1\u6536\u96c6\u5668,\u4f46\u662f\u4e32\u884c\u6536\u96c6\u5668\u53ea\u9002\u7528\u4e8e\u5c0f\u6570\u636e\u91cf\u7684\u60c5\u51b5,\u6240\u4ee5\u8fd9\u91cc\u7684\u9009\u62e9\u4e3b\u8981\u9488\u5bf9\u5e76\u884c\u6536\u96c6\u5668\u548c\u5e76\u53d1\u6536\u96c6\u5668.\u9ed8\u8ba4 \u60c5\u51b5\u4e0b,JDK5.0\u4ee5\u524d\u90fd\u662f\u4f7f\u7528\u4e32\u884c\u6536\u96c6\u5668,\u5982\u679c\u60f3\u4f7f\u7528\u5176\u4ed6\u6536\u96c6\u5668\u9700\u8981\u5728\u542f\u52a8\u65f6\u52a0\u5165\u76f8\u5e94\u53c2\u6570.JDK5.0\u4ee5\u540e,JVM\u4f1a\u6839\u636e\u5f53\u524d\u7cfb\u7edf\u914d\u7f6e\u8fdb\u884c\u5224\u65ad.
\n\u541e\u5410\u91cf\u4f18\u5148\u7684\u5e76\u884c\u6536\u96c6\u5668
\n\u5982\u4e0a\u6587\u6240\u8ff0,\u5e76\u884c\u6536\u96c6\u5668\u4e3b\u8981\u4ee5\u5230\u8fbe\u4e00\u5b9a\u7684\u541e\u5410\u91cf\u4e3a\u76ee\u6807,\u9002\u7528\u4e8e\u79d1\u5b66\u6280\u672f\u548c\u540e\u53f0\u5904\u7406\u7b49.
\n\u5178\u578b\u914d\u7f6e:
\njava -Xmx3800m -Xms3800m -Xmn2g -Xss128k -XX:+UseParallelGC -XX:ParallelGCThreads=20
\n-XX:+UseParallelGC:\u9009\u62e9\u5783\u573e\u6536\u96c6\u5668\u4e3a\u5e76\u884c\u6536\u96c6\u5668.\u6b64\u914d\u7f6e\u4ec5\u5bf9\u5e74\u8f7b\u4ee3\u6709\u6548.\u5373\u4e0a\u8ff0\u914d\u7f6e\u4e0b,\u5e74\u8f7b\u4ee3\u4f7f\u7528\u5e76\u53d1\u6536\u96c6,\u800c\u5e74\u8001\u4ee3\u4ecd\u65e7\u4f7f\u7528\u4e32\u884c\u6536\u96c6.
\n-XX:ParallelGCThreads=20:\u914d\u7f6e\u5e76\u884c\u6536\u96c6\u5668\u7684\u7ebf\u7a0b\u6570,\u5373:\u540c\u65f6\u591a\u5c11\u4e2a\u7ebf\u7a0b\u4e00\u8d77\u8fdb\u884c\u5783\u573e\u56de\u6536.\u6b64\u503c\u6700\u597d\u914d\u7f6e\u4e0e\u5904\u7406\u5668\u6570\u76ee\u76f8\u7b49.<\/p>\n

java -Xmx3550m -Xms3550m -Xmn2g -Xss128k -XX:+UseParallelGC -XX:ParallelGCThreads=20 -XX:+UseParallelOldGC
\n-XX:+UseParallelOldGC:\u914d\u7f6e\u5e74\u8001\u4ee3\u5783\u573e\u6536\u96c6\u65b9\u5f0f\u4e3a\u5e76\u884c\u6536\u96c6.JDK6.0\u652f\u6301\u5bf9\u5e74\u8001\u4ee3\u5e76\u884c\u6536\u96c6.<\/p>\n

java -Xmx3550m -Xms3550m -Xmn2g -Xss128k -XX:+UseParallelGC -XX:MaxGCPauseMillis=100
\n-XX:MaxGCPauseMillis=100:\u8bbe\u7f6e\u6bcf\u6b21\u5e74\u8f7b\u4ee3\u5783\u573e\u56de\u6536\u7684\u6700\u957f\u65f6\u95f4,\u5982\u679c\u65e0\u6cd5\u6ee1\u8db3\u6b64\u65f6\u95f4,JVM\u4f1a\u81ea\u52a8\u8c03\u6574\u5e74\u8f7b\u4ee3\u5927\u5c0f,\u4ee5\u6ee1\u8db3\u6b64\u503c.<\/p>\n

java -Xmx3550m -Xms3550m -Xmn2g -Xss128k -XX:+UseParallelGC -XX:MaxGCPauseMillis=100 -XX:+UseAdaptiveSizePolicy
\n-XX:+UseAdaptiveSizePolicy:\u8bbe\u7f6e\u6b64\u9009\u9879\u540e,\u5e76\u884c\u6536\u96c6\u5668\u4f1a\u81ea\u52a8\u9009\u62e9\u5e74\u8f7b\u4ee3\u533a\u5927\u5c0f\u548c\u76f8\u5e94\u7684Survivor\u533a\u6bd4\u4f8b,\u4ee5\u8fbe\u5230\u76ee\u6807\u7cfb\u7edf\u89c4\u5b9a\u7684\u6700\u4f4e\u76f8\u5e94\u65f6\u95f4\u6216\u8005\u6536\u96c6\u9891\u7387\u7b49,\u6b64\u503c\u5efa\u8bae\u4f7f\u7528\u5e76\u884c\u6536\u96c6\u5668\u65f6,\u4e00\u76f4\u6253\u5f00.<\/p>\n

\u54cd\u5e94\u65f6\u95f4\u4f18\u5148\u7684\u5e76\u53d1\u6536\u96c6\u5668<\/strong>
\n\u5982\u4e0a\u6587\u6240\u8ff0,\u5e76\u53d1\u6536\u96c6\u5668\u4e3b\u8981\u662f\u4fdd\u8bc1\u7cfb\u7edf\u7684\u54cd\u5e94\u65f6\u95f4,\u51cf\u5c11\u5783\u573e\u6536\u96c6\u65f6\u7684\u505c\u987f\u65f6\u95f4.\u9002\u7528\u4e8e\u5e94\u7528\u670d\u52a1\u5668,\u7535\u4fe1\u9886\u57df\u7b49.
\n\u5178\u578b\u914d\u7f6e:
\njava -Xmx3550m -Xms3550m -Xmn2g -Xss128k -XX:ParallelGCThreads=20 -XX:+UseConcMarkSweepGC -XX:+UseParNewGC
\n-XX:+UseConcMarkSweepGC:\u8bbe\u7f6e\u5e74\u8001\u4ee3\u4e3a\u5e76\u53d1\u6536\u96c6.\u6d4b\u8bd5\u4e2d\u914d\u7f6e\u8fd9\u4e2a\u4ee5\u540e,-XX:NewRatio=4\u7684\u914d\u7f6e\u5931\u6548\u4e86,\u539f\u56e0\u4e0d\u660e.\u6240\u4ee5,\u6b64\u65f6\u5e74\u8f7b\u4ee3\u5927\u5c0f\u6700\u597d\u7528-Xmn\u8bbe\u7f6e.
\n-XX:+UseParNewGC:\u8bbe\u7f6e\u5e74\u8f7b\u4ee3\u4e3a\u5e76\u884c\u6536\u96c6.\u53ef\u4e0eCMS\u6536\u96c6\u540c\u65f6\u4f7f\u7528.JDK5.0\u4ee5\u4e0a,JVM\u4f1a\u6839\u636e\u7cfb\u7edf\u914d\u7f6e\u81ea\u884c\u8bbe\u7f6e,\u6240\u4ee5\u65e0\u9700\u518d\u8bbe\u7f6e\u6b64\u503c.
\njava -Xmx3550m -Xms3550m -Xmn2g -Xss128k -XX:+UseConcMarkSweepGC -XX:CMSFullGCsBeforeCompaction=5 -XX:+UseCMSCompactAtFullCollection
\n-XX:CMSFullGCsBeforeCompaction:\u7531\u4e8e\u5e76\u53d1\u6536\u96c6\u5668\u4e0d\u5bf9\u5185\u5b58\u7a7a\u95f4\u8fdb\u884c\u538b\u7f29,\u6574\u7406,\u6240\u4ee5\u8fd0\u884c\u4e00\u6bb5\u65f6\u95f4\u4ee5\u540e\u4f1a\u4ea7\u751f”\u788e\u7247”,\u4f7f\u5f97\u8fd0\u884c\u6548\u7387\u964d\u4f4e.\u6b64\u503c\u8bbe\u7f6e\u8fd0\u884c\u591a\u5c11\u6b21GC\u4ee5\u540e\u5bf9\u5185\u5b58\u7a7a\u95f4\u8fdb\u884c\u538b\u7f29,\u6574\u7406.
\n-XX:+UseCMSCompactAtFullCollection:\u6253\u5f00\u5bf9\u5e74\u8001\u4ee3\u7684\u538b\u7f29.\u53ef\u80fd\u4f1a\u5f71\u54cd\u6027\u80fd,\u4f46\u662f\u53ef\u4ee5\u6d88\u9664\u788e\u7247<\/p>\n

\u8f85\u52a9\u4fe1\u606f<\/strong>
\nJVM\u63d0\u4f9b\u4e86\u5927\u91cf\u547d\u4ee4\u884c\u53c2\u6570,\u6253\u5370\u4fe1\u606f,\u4f9b\u8c03\u8bd5\u4f7f\u7528.\u4e3b\u8981\u6709\u4ee5\u4e0b\u4e00\u4e9b:
\n-XX:+PrintGC
\n\u8f93\u51fa\u5f62\u5f0f:[GC 118250K->113543K(130112K), 0.0094143 secs]
\n[Full GC 121376K->10414K(130112K), 0.0650971 secs]<\/p>\n

-XX:+PrintGCDetails
\n\u8f93\u51fa\u5f62\u5f0f:[GC [DefNew: 8614K->781K(9088K), 0.0123035 secs] 118250K->113543K(130112K), 0.0124633 secs]
\n[GC [DefNew: 8614K->8614K(9088K), 0.0000665 secs][Tenured: 112761K->10414K(121024K), 0.0433488 secs] 121376K->10414K(130112K), 0.0436268 secs]<\/p>\n

-XX:+PrintGCTimeStamps -XX:+PrintGC:PrintGCTimeStamps\u53ef\u4e0e\u4e0a\u9762\u4e24\u4e2a\u6df7\u5408\u4f7f\u7528
\n\u8f93\u51fa\u5f62\u5f0f:11.851: [GC 98328K->93620K(130112K), 0.0082960 secs]<\/p>\n

-XX:+PrintGCApplicationConcurrentTime:\u6253\u5370\u6bcf\u6b21\u5783\u573e\u56de\u6536\u524d,\u7a0b\u5e8f\u672a\u4e2d\u65ad\u7684\u6267\u884c\u65f6\u95f4.\u53ef\u4e0e\u4e0a\u9762\u6df7\u5408\u4f7f\u7528
\n\u8f93\u51fa\u5f62\u5f0f:Application time: 0.5291524 seconds<\/p>\n

-XX:+PrintGCApplicationStoppedTime:\u6253\u5370\u5783\u573e\u56de\u6536\u671f\u95f4\u7a0b\u5e8f\u6682\u505c\u7684\u65f6\u95f4.\u53ef\u4e0e\u4e0a\u9762\u6df7\u5408\u4f7f\u7528
\n\u8f93\u51fa\u5f62\u5f0f:Total time for which application threads were stopped: 0.0468229 seconds<\/p>\n

-XX:PrintHeapAtGC:\u6253\u5370GC\u524d\u540e\u7684\u8be6\u7ec6\u5806\u6808\u4fe1\u606f
\n\u8f93\u51fa\u5f62\u5f0f:
\n34.702: [GC {Heap before gc invocations=7:
\ndef new generation total 55296K, used 52568K [0x1ebd0000, 0x227d0000, 0x227d0000)
\neden space 49152K, 99% used [0x1ebd0000, 0x21bce430, 0x21bd0000)
\nfrom space 6144K, 55% used [0x221d0000, 0x22527e10, 0x227d0000)
\nto space 6144K, 0% used [0x21bd0000, 0x21bd0000, 0x221d0000)
\ntenured generation total 69632K, used 2696K [0x227d0000, 0x26bd0000, 0x26bd0000)
\nthe space 69632K, 3% used [0x227d0000, 0x22a720f8, 0x22a72200, 0x26bd0000)
\ncompacting perm gen total 8192K, used 2898K [0x26bd0000, 0x273d0000, 0x2abd0000)
\nthe space 8192K, 35% used [0x26bd0000, 0x26ea4ba8, 0x26ea4c00, 0x273d0000)
\nro space 8192K, 66% used [0x2abd0000, 0x2b12bcc0, 0x2b12be00, 0x2b3d0000)
\nrw space 12288K, 46% used [0x2b3d0000, 0x2b972060, 0x2b972200, 0x2bfd0000)
\n34.735: [DefNew: 52568K->3433K(55296K), 0.0072126 secs] 55264K->6615K(124928K)Heap after gc invocations=8:
\ndef new generation total 55296K, used 3433K [0x1ebd0000, 0x227d0000, 0x227d0000)
\neden space 49152K, 0% used [0x1ebd0000, 0x1ebd0000, 0x21bd0000)
\nfrom space 6144K, 55% used [0x21bd0000, 0x21f2a5e8, 0x221d0000)
\nto space 6144K, 0% used [0x221d0000, 0x221d0000, 0x227d0000)
\ntenured generation total 69632K, used 3182K [0x227d0000, 0x26bd0000, 0x26bd0000)
\nthe space 69632K, 4% used [0x227d0000, 0x22aeb958, 0x22aeba00, 0x26bd0000)
\ncompacting perm gen total 8192K, used 2898K [0x26bd0000, 0x273d0000, 0x2abd0000)
\nthe space 8192K, 35% used [0x26bd0000, 0x26ea4ba8, 0x26ea4c00, 0x273d0000)
\nro space 8192K, 66% used [0x2abd0000, 0x2b12bcc0, 0x2b12be00, 0x2b3d0000)
\nrw space 12288K, 46% used [0x2b3d0000, 0x2b972060, 0x2b972200, 0x2bfd0000)
\n}
\n, 0.0757599 secs]<\/p>\n

-Xloggc:filename:\u4e0e\u4e0a\u9762\u51e0\u4e2a\u914d\u5408\u4f7f\u7528,\u628a\u76f8\u5173\u65e5\u5fd7\u4fe1\u606f\u8bb0\u5f55\u5230\u6587\u4ef6\u4ee5\u4fbf\u5206\u6790.
\n\u5e38\u89c1\u914d\u7f6e\u6c47\u603b\u00a0<\/strong>
\n\u5806\u8bbe\u7f6e
\n-Xms:\u521d\u59cb\u5806\u5927\u5c0f
\n-Xmx:\u6700\u5927\u5806\u5927\u5c0f
\n-XX:NewSize=n:\u8bbe\u7f6e\u5e74\u8f7b\u4ee3\u5927\u5c0f
\n-XX:NewRatio=n:\u8bbe\u7f6e\u5e74\u8f7b\u4ee3\u548c\u5e74\u8001\u4ee3\u7684\u6bd4\u503c.\u5982:\u4e3a3,\u8868\u793a\u5e74\u8f7b\u4ee3\u4e0e\u5e74\u8001\u4ee3\u6bd4\u503c\u4e3a1:3,\u5e74\u8f7b\u4ee3\u5360\u6574\u4e2a\u5e74\u8f7b\u4ee3\u5e74\u8001\u4ee3\u548c\u76841\/4
\n-XX:SurvivorRatio=n:\u5e74\u8f7b\u4ee3\u4e2dEden\u533a\u4e0e\u4e24\u4e2aSurvivor\u533a\u7684\u6bd4\u503c.\u6ce8\u610fSurvivor\u533a\u6709\u4e24\u4e2a.\u5982:3,\u8868\u793aEden:Survivor=3:2,\u4e00\u4e2aSurvivor\u533a\u5360\u6574\u4e2a\u5e74\u8f7b\u4ee3\u76841\/5
\n-XX:MaxPermSize=n:\u8bbe\u7f6e\u6301\u4e45\u4ee3\u5927\u5c0f
\n\u6536\u96c6\u5668\u8bbe\u7f6e
\n-XX:+UseSerialGC:\u8bbe\u7f6e\u4e32\u884c\u6536\u96c6\u5668
\n-XX:+UseParallelGC:\u8bbe\u7f6e\u5e76\u884c\u6536\u96c6\u5668
\n-XX:+UseParalledlOldGC:\u8bbe\u7f6e\u5e76\u884c\u5e74\u8001\u4ee3\u6536\u96c6\u5668
\n-XX:+UseConcMarkSweepGC:\u8bbe\u7f6e\u5e76\u53d1\u6536\u96c6\u5668
\n\u5783\u573e\u56de\u6536\u7edf\u8ba1\u4fe1\u606f
\n-XX:+PrintGC
\n-XX:+PrintGCDetails
\n-XX:+PrintGCTimeStamps
\n-Xloggc:filename
\n\u5e76\u884c\u6536\u96c6\u5668\u8bbe\u7f6e
\n-XX:ParallelGCThreads=n:\u8bbe\u7f6e\u5e76\u884c\u6536\u96c6\u5668\u6536\u96c6\u65f6\u4f7f\u7528\u7684CPU\u6570.\u5e76\u884c\u6536\u96c6\u7ebf\u7a0b\u6570.
\n-XX:MaxGCPauseMillis=n:\u8bbe\u7f6e\u5e76\u884c\u6536\u96c6\u6700\u5927\u6682\u505c\u65f6\u95f4
\n-XX:GCTimeRatio=n:\u8bbe\u7f6e\u5783\u573e\u56de\u6536\u65f6\u95f4\u5360\u7a0b\u5e8f\u8fd0\u884c\u65f6\u95f4\u7684\u767e\u5206\u6bd4.\u516c\u5f0f\u4e3a1\/(1+n)
\n\u5e76\u53d1\u6536\u96c6\u5668\u8bbe\u7f6e
\n-XX:+CMSIncrementalMode:\u8bbe\u7f6e\u4e3a\u589e\u91cf\u6a21\u5f0f.\u9002\u7528\u4e8e\u5355CPU\u60c5\u51b5.
\n-XX:ParallelGCThreads=n:\u8bbe\u7f6e\u5e76\u53d1\u6536\u96c6\u5668\u5e74\u8f7b\u4ee3\u6536\u96c6\u65b9\u5f0f\u4e3a\u5e76\u884c\u6536\u96c6\u65f6,\u4f7f\u7528\u7684CPU\u6570.\u5e76\u884c\u6536\u96c6\u7ebf\u7a0b\u6570.<\/p>\n

\u8c03\u4f18\u603b\u7ed3\u00a0<\/strong>
\n\u5e74\u8f7b\u4ee3\u5927\u5c0f\u9009\u62e9
\n\u54cd\u5e94\u65f6\u95f4\u4f18\u5148\u7684\u5e94\u7528:\u5c3d\u53ef\u80fd\u8bbe\u5927,\u76f4\u5230\u63a5\u8fd1\u7cfb\u7edf\u7684\u6700\u4f4e\u54cd\u5e94\u65f6\u95f4\u9650\u5236(\u6839\u636e\u5b9e\u9645\u60c5\u51b5\u9009\u62e9).\u5728\u6b64\u79cd\u60c5\u51b5\u4e0b,\u5e74\u8f7b\u4ee3\u6536\u96c6\u53d1\u751f\u7684\u9891\u7387\u4e5f\u662f\u6700\u5c0f\u7684.\u540c\u65f6,\u51cf\u5c11\u5230\u8fbe\u5e74\u8001\u4ee3\u7684\u5bf9\u8c61.
\n\u541e\u5410\u91cf\u4f18\u5148\u7684\u5e94\u7528:\u5c3d\u53ef\u80fd\u7684\u8bbe\u7f6e\u5927,\u53ef\u80fd\u5230\u8fbeGbit\u7684\u7a0b\u5ea6.\u56e0\u4e3a\u5bf9\u54cd\u5e94\u65f6\u95f4\u6ca1\u6709\u8981\u6c42,\u5783\u573e\u6536\u96c6\u53ef\u4ee5\u5e76\u884c\u8fdb\u884c,\u4e00\u822c\u9002\u54088CPU\u4ee5\u4e0a\u7684\u5e94\u7528.
\n\u5e74\u8001\u4ee3\u5927\u5c0f\u9009\u62e9
\n\u54cd\u5e94\u65f6\u95f4\u4f18\u5148\u7684\u5e94\u7528:\u5e74\u8001\u4ee3\u4f7f\u7528\u5e76\u53d1\u6536\u96c6\u5668,\u6240\u4ee5\u5176\u5927\u5c0f\u9700\u8981\u5c0f\u5fc3\u8bbe\u7f6e,\u4e00\u822c\u8981\u8003\u8651\u5e76\u53d1\u4f1a\u8bdd\u7387\u548c\u4f1a\u8bdd\u6301\u7eed\u65f6\u95f4\u7b49\u4e00\u4e9b\u53c2\u6570.\u5982\u679c\u5806\u8bbe\u7f6e\u5c0f\u4e86,\u53ef\u4ee5\u4f1a\u9020\u6210\u5185\u5b58\u788e \u7247,\u9ad8\u56de\u6536\u9891\u7387\u4ee5\u53ca\u5e94\u7528\u6682\u505c\u800c\u4f7f\u7528\u4f20\u7edf\u7684\u6807\u8bb0\u6e05\u9664\u65b9\u5f0f;\u5982\u679c\u5806\u5927\u4e86,\u5219\u9700\u8981\u8f83\u957f\u7684\u6536\u96c6\u65f6\u95f4.\u6700\u4f18\u5316\u7684\u65b9\u6848,\u4e00\u822c\u9700\u8981\u53c2\u8003\u4ee5\u4e0b\u6570\u636e\u83b7\u5f97:
\n\u5e76\u53d1\u5783\u573e\u6536\u96c6\u4fe1\u606f
\n\u6301\u4e45\u4ee3\u5e76\u53d1\u6536\u96c6\u6b21\u6570
\n\u4f20\u7edfGC\u4fe1\u606f
\n\u82b1\u5728\u5e74\u8f7b\u4ee3\u548c\u5e74\u8001\u4ee3\u56de\u6536\u4e0a\u7684\u65f6\u95f4\u6bd4\u4f8b
\n\u51cf\u5c11\u5e74\u8f7b\u4ee3\u548c\u5e74\u8001\u4ee3\u82b1\u8d39\u7684\u65f6\u95f4,\u4e00\u822c\u4f1a\u63d0\u9ad8\u5e94\u7528\u7684\u6548\u7387<\/p>\n

\u541e\u5410\u91cf\u4f18\u5148\u7684\u5e94\u7528:\u4e00\u822c\u541e\u5410\u91cf\u4f18\u5148\u7684\u5e94\u7528\u90fd\u6709\u4e00\u4e2a\u5f88\u5927\u7684\u5e74\u8f7b\u4ee3\u548c\u4e00\u4e2a\u8f83\u5c0f\u7684\u5e74\u8001\u4ee3.\u539f\u56e0\u662f,\u8fd9\u6837\u53ef\u4ee5\u5c3d\u53ef\u80fd\u56de\u6536\u6389\u5927\u90e8\u5206\u77ed\u671f\u5bf9\u8c61,\u51cf\u5c11\u4e2d\u671f\u7684\u5bf9\u8c61,\u800c\u5e74\u8001\u4ee3\u5c3d\u5b58\u653e\u957f\u671f\u5b58\u6d3b\u5bf9\u8c61.
\n\u8f83\u5c0f\u5806\u5f15\u8d77\u7684\u788e\u7247\u95ee\u9898
\n\u56e0\u4e3a\u5e74\u8001\u4ee3\u7684\u5e76\u53d1\u6536\u96c6\u5668\u4f7f\u7528\u6807\u8bb0,\u6e05\u9664\u7b97\u6cd5,\u6240\u4ee5\u4e0d\u4f1a\u5bf9\u5806\u8fdb\u884c\u538b\u7f29.\u5f53\u6536\u96c6\u5668\u56de\u6536\u65f6,\u4ed6\u4f1a\u628a\u76f8\u90bb\u7684\u7a7a\u95f4\u8fdb\u884c\u5408\u5e76,\u8fd9\u6837\u53ef\u4ee5\u5206\u914d\u7ed9\u8f83\u5927\u7684\u5bf9\u8c61.\u4f46\u662f,\u5f53\u5806\u7a7a \u95f4\u8f83\u5c0f\u65f6,\u8fd0\u884c\u4e00\u6bb5\u65f6\u95f4\u4ee5\u540e,\u5c31\u4f1a\u51fa\u73b0”\u788e\u7247”,\u5982\u679c\u5e76\u53d1\u6536\u96c6\u5668\u627e\u4e0d\u5230\u8db3\u591f\u7684\u7a7a\u95f4,\u90a3\u4e48\u5e76\u53d1\u6536\u96c6\u5668\u5c06\u4f1a\u505c\u6b62,\u7136\u540e\u4f7f\u7528\u4f20\u7edf\u7684\u6807\u8bb0,\u6e05\u9664\u65b9\u5f0f\u8fdb\u884c\u56de\u6536.\u5982\u679c \u51fa\u73b0”\u788e\u7247”,\u53ef\u80fd\u9700\u8981\u8fdb\u884c\u5982\u4e0b\u914d\u7f6e:
\n-XX:+UseCMSCompactAtFullCollection:\u4f7f\u7528\u5e76\u53d1\u6536\u96c6\u5668\u65f6,\u5f00\u542f\u5bf9\u5e74\u8001\u4ee3\u7684\u538b\u7f29.
\n-XX:CMSFullGCsBeforeCompaction=0:\u4e0a\u9762\u914d\u7f6e\u5f00\u542f\u7684\u60c5\u51b5\u4e0b,\u8fd9\u91cc\u8bbe\u7f6e\u591a\u5c11\u6b21Full GC\u540e,\u5bf9\u5e74\u8001\u4ee3\u8fdb\u884c\u538b\u7f29<\/p>\n

\u5728\u540c\u4e00\u4e2a\u5de5\u7a0b\u4e0b,\u6709\u4e24\u4e2a\u7c7b,\u8fd9\u4e24\u4e2a\u7c7b\u4e2d\u53ea\u6709\u5f88\u5c11\u7684\u53d8\u52a8,\u800c\u6700\u5173\u5065\u7684FOR\u5374\u6ca1\u6709\u4e00\u70b9\u53d8\u52a8,\u53ef\u662f\u5f53\u6211\u5206\u522b\u8fd0\u884c\u8fd9\u4e24\u4e2a\u7a0b\u5e8f\u7684\u65f6\u5019\u5374\u51fa\u73b0\u4e00\u4e2a\u5f88\u4e25\u91cd\u7684\u95ee\u9898,\u4e00\u4e2a\u7a0b\u5e8f\u5faa\u73af\u7684\u5feb,\u4e00\u4e2a\u5faa\u73af\u7684\u6162.\u8fd9\u5230\u5e95\u662f\u600e\u4e48\u56de\u4e8b\u5462~???\u82e6\u82e6\u5bfb\u627e\u4e86\u534a\u5929\u4e5f\u6ca1\u6709\u60f3\u5230\u662f\u4e3a\u4ec0\u4e48,\u56e0\u4e3a\u7a0b\u5e8f\u6539\u53d8\u7684\u90e8\u5206\u6839\u4e0d\u5f71\u54cd\u6211\u5faa\u73af\u7684\u901f\u5ea6,\u53ef\u662f\u7ed3\u679c\u5374\u662f\u6709\u5f88\u5927\u7684\u5dee\u522b,\u4e00\u4e2a\u5927\u7ea6\u662f\u5728\u4e00\u5206\u949f\u8fd9\u5185\u5c31\u53ef\u4ee5\u5faa\u73af\u5b8c,\u53ef\u662f\u53e6\u4e00\u4e2a\u5374\u9700\u8981\u516d\u4e03\u5206\u949f,\u8fd9\u6839\u672c\u5c31\u4e0d\u662f\u4e00\u4e2a\u6570\u636e\u7406\u7ea7\u7684\u9ebb.\u4e24\u4e2a\u5b8c\u5168\u4e00\u6837\u7684\u5faa\u73af,\u4ece\u4ee3\u7801\u4e0a\u6839\u672c\u4e0a\u662f\u770b\u4e0d\u51fa\u6709\u4ec0\u4e48\u95ee\u9898.\u4e0d\u5f97\u4ee5\u6c42\u52a9\u540c\u4e8b\u5427,\u53ef\u662f\u540c\u4e8b\u770b\u4e86\u4e5f\u611f\u89c9\u5f88\u8be1\u5f02,\u4e24\u4e2a\u4eba\u5728\u90a3\u8ba2\u7740\u4ee3\u7801\u53c8\u770b\u4e86\u4e00\u4e2a\u591a\u5c0f\u65f6,\u6700\u540e\u540c\u4e8b\u8ba9\u6211\u6765\u4e2a\u5e72\u51c0\u70b9\u7684,\u5173\u673a\u91cd\u542f.\u6211\u5230\u4e5f\u542c\u8bdd,\u5c31\u987a\u7740\u540c\u4e8b\u7684\u610f\u601d\u53bb\u4e86,\u53ef\u5c31\u5728\u5173\u673a\u7684\u8fd9\u4e2a\u65f6\u5019\u4ed6\u7a81\u7136\u8bf4\u662f\u4e0d\u662f\u5185\u5b58\u7684\u95ee\u9898,\u6211\u4e5f\u7a7a\u7136\u60f3\u5230\u4e86,\u8fd8\u771f\u7684\u6709\u53ef\u80fd\u662f\u5185\u5b58\u7684\u95ee\u9898,\u56e0\u4e3a\u5feb\u7684\u90a3\u4e2a\u5728\u6211\u4e4b\u524d\u8fd0\u884c\u7a0b\u5e8f\u4e4b\u524d\u53ef\u7ed9\u8fc71G\u7684\u5185\u5b58\u554a,\u800c\u540e\u6765\u7684\u8fd9\u4e2a\u6211\u597d\u50cf\u662f\u6ca1\u6709\u8bbe\u8fc7\u5185\u5b58\u554a,\u673a\u5668\u8d77\u6765\u4e86,\u6709\u4e86\u8fd9\u4e2a\u60f3\u6cd5\u8fdb\u53bb\u770b\u770b\u5427,\u7ed3\u679c\u6b63\u4e2d\u8981\u5bb3,\u679c\u771f\u662f\u6162\u7684\u90a3\u4e2a\u6ca1\u6709\u5f00\u5185\u5b58,\u7a0b\u5e8f\u8fd0\u884c\u65f6\u53ea\u4e0d\u8fc7\u662fJVM\u9ed8\u8ba4\u5f00\u7684\u5185\u5b58.\u6211\u521d\u6b65\u5206\u6790\u662f\u56e0\u4e3a\u5185\u5b58\u592a\u5c0f,\u800c\u6211\u7684\u7a0b\u5e8f\u6240\u7528\u5185\u5b58\u53c8\u6b63\u597d\u5361\u5728JVM\u6240\u5f00\u5185\u5b58\u8fb9\u4e0a,\u4e0d\u81f3\u4e8e\u6ea2\u51fa.\u5f53\u7a0b\u5e8f\u8fd0\u884c\u65f6\u5c31\u5f97\u82b1\u8d39\u5927\u90e8\u5206\u65f6\u95f4\u53bb\u8c03\u7528GC\u53bb,\u8fd9\u6837\u5c31\u5bfc\u81f4\u4e86\u4e3a\u4ec0\u4e48\u76f8\u540c\u7684\u5faa\u73af\u51fa\u73b0\u4e24\u79cd\u4e0d\u540c\u7684\u6548\u7387~!
\n\u987a\u4fbf\u628a\u5185\u5b58\u4f7f\u7528\u60c5\u51b5\u7684\u65b9\u6cd5\u4e5f\u8d34\u51fa\u6765:
\npublic static String getMemUsage() {
\nlong free = java.lang.Runtime.getRuntime().freeMemory();
\nlong total = java.lang.Runtime.getRuntime().totalMemory();
\nStringBuffer buf = new StringBuffer();
\nbuf.append(“[Mem: used “).append((total-free)>>20)
\n.append(“M free “).append(free>>20)
\n.append(“M total “).append(total>>20).append(“M]”);
\nreturn buf.toString();
\n}<\/p>\n

google\u4e00\u4e0b,\u5927\u6982\u5c31\u8bf4JVM\u662f\u8fd9\u6837\u6765\u64cd\u4f5c\u5185\u5b58:
\n\u5806(Heap)\u548c\u975e\u5806(Non-heap)\u5185\u5b58
\n\u6309\u7167\u5b98\u65b9\u7684\u8bf4\u6cd5:”Java \u865a\u62df\u673a\u5177\u6709\u4e00\u4e2a\u5806,\u5806\u662f\u8fd0\u884c\u65f6\u6570\u636e\u533a\u57df,\u6240\u6709\u7c7b\u5b9e\u4f8b\u548c\u6570\u7ec4\u7684\u5185\u5b58\u5747\u4ece\u6b64\u5904\u5206\u914d.\u5806\u662f\u5728 Java \u865a\u62df\u673a\u542f\u52a8\u65f6\u521b\u5efa\u7684.””\u5728JVM\u4e2d\u5806\u4e4b\u5916\u7684\u5185\u5b58\u79f0\u4e3a\u975e\u5806\u5185\u5b58(Non-heap memory)”.\u53ef\u4ee5\u770b\u51faJVM\u4e3b\u8981\u7ba1\u7406\u4e24\u79cd\u7c7b\u578b\u7684\u5185\u5b58:\u5806\u548c\u975e\u5806.\u7b80\u5355\u6765\u8bf4\u5806\u5c31\u662fJava\u4ee3\u7801\u53ef\u53ca\u7684\u5185\u5b58,\u662f\u7559\u7ed9\u5f00\u53d1\u4eba\u5458\u4f7f\u7528\u7684;\u975e\u5806\u5c31\u662fJVM\u7559\u7ed9\u81ea\u5df1\u7528\u7684,\u6240\u4ee5\u65b9\u6cd5\u533a,JVM\u5185\u90e8\u5904\u7406\u6216\u4f18\u5316\u6240\u9700\u7684\u5185\u5b58(\u5982JIT\u7f16\u8bd1\u540e\u7684\u4ee3\u7801\u7f13\u5b58),\u6bcf\u4e2a\u7c7b\u7ed3\u6784(\u5982\u8fd0\u884c\u65f6\u5e38\u6570\u6c60,\u5b57\u6bb5\u548c\u65b9\u6cd5\u6570\u636e)\u4ee5\u53ca\u65b9\u6cd5\u548c\u6784\u9020\u65b9\u6cd5\u7684\u4ee3\u7801\u90fd\u5728\u975e\u5806\u5185\u5b58\u4e2d.
\n\u5806\u5185\u5b58\u5206\u914d
\nJVM\u521d\u59cb\u5206\u914d\u7684\u5185\u5b58\u7531-Xms\u6307\u5b9a,\u9ed8\u8ba4\u662f\u7269\u7406\u5185\u5b58\u76841\/64;JVM\u6700\u5927\u5206\u914d\u7684\u5185\u5b58\u7531-Xmx\u6307\u5b9a,\u9ed8\u8ba4\u662f\u7269\u7406\u5185\u5b58\u76841\/4.\u9ed8\u8ba4\u7a7a\u4f59\u5806\u5185\u5b58\u5c0f\u4e8e40%\u65f6,JVM\u5c31\u4f1a\u589e\u5927\u5806\u76f4\u5230-Xmx\u7684\u6700\u5927\u9650\u5236;\u7a7a\u4f59\u5806\u5185\u5b58\u5927\u4e8e70%\u65f6, JVM\u4f1a\u51cf\u5c11\u5806\u76f4\u5230-Xms\u7684\u6700\u5c0f\u9650\u5236.\u56e0\u6b64\u670d\u52a1\u5668\u4e00\u822c\u8bbe\u7f6e-Xms,-Xmx\u76f8\u7b49\u4ee5\u907f\u514d\u5728\u6bcf\u6b21GC \u540e\u8c03\u6574\u5806\u7684\u5927\u5c0f.
\n\u975e\u5806\u5185\u5b58\u5206\u914d
\nJVM\u4f7f\u7528-XX:PermSize\u8bbe\u7f6e\u975e\u5806\u5185\u5b58\u521d\u59cb\u503c,\u9ed8\u8ba4\u662f\u7269\u7406\u5185\u5b58\u76841\/64;\u7531XX:MaxPermSize\u8bbe\u7f6e\u6700\u5927\u975e\u5806\u5185\u5b58\u7684\u5927\u5c0f,\u9ed8\u8ba4\u662f\u7269\u7406\u5185\u5b58\u76841\/4.
\nJVM\u5185\u5b58\u9650\u5236(\u6700\u5927\u503c)
\n\u9996\u5148JVM\u5185\u5b58\u9996\u5148\u53d7\u9650\u4e8e\u5b9e\u9645\u7684\u6700\u5927\u7269\u7406\u5185\u5b58,\u5047\u8bbe\u7269\u7406\u5185\u5b58\u65e0\u9650\u5927\u7684\u8bdd,JVM\u5185\u5b58\u7684\u6700\u5927\u503c\u8ddf\u64cd\u4f5c\u7cfb\u7edf\u6709\u5f88\u5927\u7684\u5173\u7cfb.\u7b80\u5355\u7684\u8bf4\u5c3132\u4f4d\u5904\u7406\u5668\u867d\u7136\u53ef\u63a7\u5185\u5b58\u7a7a\u95f4\u67094GB,\u4f46\u662f\u5177\u4f53\u7684\u64cd\u4f5c\u7cfb\u7edf\u4f1a\u7ed9\u4e00\u4e2a\u9650\u5236,\u8fd9\u4e2a\u9650\u5236\u4e00\u822c\u662f 2GB-3GB(\u4e00\u822c\u6765\u8bf4Windows\u7cfb\u7edf\u4e0b\u4e3a1.5G-2G,Linux\u7cfb\u7edf\u4e0b\u4e3a2G-3G),\u800c64bit\u4ee5\u4e0a\u7684\u5904\u7406\u5668\u5c31\u4e0d\u4f1a\u6709\u9650\u5236\u4e86
\nJVM\u5185\u5b58\u7684\u8c03\u4f18
\n1. Heap\u8bbe\u5b9a\u4e0e\u5783\u573e\u56de\u6536Java Heap\u5206\u4e3a3\u4e2a\u533a,Young,Old\u548cPermanent.Young\u4fdd\u5b58\u521a\u5b9e\u4f8b\u5316\u7684\u5bf9\u8c61.\u5f53\u8be5\u533a\u88ab\u586b\u6ee1\u65f6,GC\u4f1a\u5c06\u5bf9\u8c61\u79fb\u5230Old \u533a.Permanent\u533a\u5219\u8d1f\u8d23\u4fdd\u5b58\u53cd\u5c04\u5bf9\u8c61,\u672c\u6587\u4e0d\u8ba8\u8bba\u8be5\u533a.JVM\u7684Heap\u5206\u914d\u53ef\u4ee5\u4f7f\u7528-X\u53c2\u6570\u8bbe\u5b9a,
\n-Xms
\n\u521d\u59cbHeap\u5927\u5c0f
\n-Xmx
\njava heap\u6700\u5927\u503c
\n-Xmn
\nyoung generation\u7684heap\u5927\u5c0f
\nJVM\u67092\u4e2aGC\u7ebf\u7a0b.\u7b2c\u4e00\u4e2a\u7ebf\u7a0b\u8d1f\u8d23\u56de\u6536Heap\u7684Young\u533a.\u7b2c\u4e8c\u4e2a\u7ebf\u7a0b\u5728Heap\u4e0d\u8db3\u65f6,\u904d\u5386Heap,\u5c06Young \u533a\u5347\u7ea7\u4e3aOlder\u533a.Older\u533a\u7684\u5927\u5c0f\u7b49\u4e8e-Xmx\u51cf\u53bb-Xmn,\u4e0d\u80fd\u5c06-Xms\u7684\u503c\u8bbe\u7684\u8fc7\u5927,\u56e0\u4e3a\u7b2c\u4e8c\u4e2a\u7ebf\u7a0b\u88ab\u8feb\u8fd0\u884c\u4f1a\u964d\u4f4eJVM\u7684\u6027\u80fd.
\n\u4e3a\u4ec0\u4e48\u4e00\u4e9b\u7a0b\u5e8f\u9891\u7e41\u53d1\u751fGC?\u6709\u5982\u4e0b\u539f\u56e0:
\nl \u7a0b\u5e8f\u5185\u8c03\u7528\u4e86System.gc()\u6216Runtime.gc().
\nl \u4e00\u4e9b\u4e2d\u95f4\u4ef6\u8f6f\u4ef6\u8c03\u7528\u81ea\u5df1\u7684GC\u65b9\u6cd5,\u6b64\u65f6\u9700\u8981\u8bbe\u7f6e\u53c2\u6570\u7981\u6b62\u8fd9\u4e9bGC.
\nl Java\u7684Heap\u592a\u5c0f,\u4e00\u822c\u9ed8\u8ba4\u7684Heap\u503c\u90fd\u5f88\u5c0f.
\nl \u9891\u7e41\u5b9e\u4f8b\u5316\u5bf9\u8c61,Release\u5bf9\u8c61.\u6b64\u65f6\u5c3d\u91cf\u4fdd\u5b58\u5e76\u91cd\u7528\u5bf9\u8c61,\u4f8b\u5982\u4f7f\u7528StringBuffer()\u548cString().
\n\u5982\u679c\u4f60\u53d1\u73b0\u6bcf\u6b21GC\u540e,Heap\u7684\u5269\u4f59\u7a7a\u95f4\u4f1a\u662f\u603b\u7a7a\u95f4\u768450%,\u8fd9\u8868\u793a\u4f60\u7684Heap\u5904\u4e8e\u5065\u5eb7\u72b6\u6001.\u8bb8\u591aServer\u7aef\u7684Java\u7a0b\u5e8f\u6bcf\u6b21GC\u540e\u6700\u597d\u80fd\u670965%\u7684\u5269\u4f59\u7a7a\u95f4.\u7ecf\u9a8c\u4e4b\u8c08:
\n1\uff0eServer\u7aefJVM\u6700\u597d\u5c06-Xms\u548c-Xmx\u8bbe\u4e3a\u76f8\u540c\u503c.\u4e3a\u4e86\u4f18\u5316GC,\u6700\u597d\u8ba9-Xmn\u503c\u7ea6\u7b49\u4e8e-Xmx\u76841\/3[2].
\n2\uff0e\u4e00\u4e2aGUI\u7a0b\u5e8f\u6700\u597d\u662f\u6bcf10\u523020\u79d2\u95f4\u8fd0\u884c\u4e00\u6b21GC,\u6bcf\u6b21\u5728\u534a\u79d2\u4e4b\u5185\u5b8c\u6210[2].
\n\u6ce8\u610f:
\n1\uff0e\u589e\u52a0Heap\u7684\u5927\u5c0f\u867d\u7136\u4f1a\u964d\u4f4eGC\u7684\u9891\u7387,\u4f46\u4e5f\u589e\u52a0\u4e86\u6bcf\u6b21GC\u7684\u65f6\u95f4.\u5e76\u4e14GC\u8fd0\u884c\u65f6,\u6240\u6709\u7684\u7528\u6237\u7ebf\u7a0b\u5c06\u6682\u505c,\u4e5f\u5c31\u662fGC\u671f\u95f4,Java\u5e94\u7528\u7a0b\u5e8f\u4e0d\u505a\u4efb\u4f55\u5de5\u4f5c.
\n2\uff0eHeap\u5927\u5c0f\u5e76\u4e0d\u51b3\u5b9a\u8fdb\u7a0b\u7684\u5185\u5b58\u4f7f\u7528\u91cf.\u8fdb\u7a0b\u7684\u5185\u5b58\u4f7f\u7528\u91cf\u8981\u5927\u4e8e-Xmx\u5b9a\u4e49\u7684\u503c,\u56e0\u4e3aJava\u4e3a\u5176\u4ed6\u4efb\u52a1\u5206\u914d\u5185\u5b58,\u4f8b\u5982\u6bcf\u4e2a\u7ebf\u7a0b\u7684Stack\u7b49.
\n2\uff0eStack\u7684\u8bbe\u5b9a
\n\u6bcf\u4e2a\u7ebf\u7a0b\u90fd\u6709\u4ed6\u81ea\u5df1\u7684Stack.
\n-Xss
\n\u6bcf\u4e2a\u7ebf\u7a0b\u7684Stack\u5927\u5c0f
\nStack\u7684\u5927\u5c0f\u9650\u5236\u7740\u7ebf\u7a0b\u7684\u6570\u91cf.\u5982\u679cStack\u8fc7\u5927\u5c31\u597d\u5bfc\u81f4\u5185\u5b58\u6ea2\u6f0f.-Xss\u53c2\u6570\u51b3\u5b9aStack\u5927\u5c0f,\u4f8b\u5982-Xss1024K.\u5982\u679cStack\u592a\u5c0f,\u4e5f\u4f1a\u5bfc\u81f4Stack\u6ea2\u6f0f.
\n3\uff0e\u786c\u4ef6\u73af\u5883
\n\u786c\u4ef6\u73af\u5883\u4e5f\u5f71\u54cdGC\u7684\u6548\u7387,\u4f8b\u5982\u673a\u5668\u7684\u79cd\u7c7b,\u5185\u5b58,swap\u7a7a\u95f4,\u548cCPU\u7684\u6570\u91cf.
\n\u5982\u679c\u4f60\u7684\u7a0b\u5e8f\u9700\u8981\u9891\u7e41\u521b\u5efa\u5f88\u591atransient\u5bf9\u8c61,\u4f1a\u5bfc\u81f4JVM\u9891\u7e41GC.\u8fd9\u79cd\u60c5\u51b5\u4f60\u53ef\u4ee5\u589e\u52a0\u673a\u5668\u7684\u5185\u5b58,\u6765\u51cf\u5c11Swap\u7a7a\u95f4\u7684\u4f7f\u7528[2].
\n4\uff0e4\u79cdGC
\n\u7b2c\u4e00\u79cd\uff1a\u5355\u7ebf\u7a0bGC,\u4e5f\u662f\u9ed8\u8ba4\u7684GC.,\u8be5GC\u9002\u7528\u4e8e\u5355CPU\u673a\u5668.
\n\u7b2c\u4e8c\u79cd\uff1aThroughput GC,\u662f\u591a\u7ebf\u7a0b\u7684GC,\u9002\u7528\u4e8e\u591aCPU,\u4f7f\u7528\u5927\u91cf\u7ebf\u7a0b\u7684\u7a0b\u5e8f.\u7b2c\u4e8c\u79cdGC\u4e0e\u7b2c\u4e00\u79cdGC\u76f8\u4f3c,\u4e0d\u540c\u5728\u4e8eGC\u5728\u6536\u96c6<\/p>\n

Young\u533a\u662f\u591a\u7ebf\u7a0b\u7684,\u4f46\u5728Old\u533a\u548c\u7b2c\u4e00\u79cd\u4e00\u6837,\u4ecd\u7136\u91c7\u7528\u5355\u7ebf\u7a0b.-XX:+UseParallelGC\u53c2\u6570\u542f\u52a8\u8be5GC.
\n\u7b2c\u4e09\u79cd\uff1aConcurrent Low Pause GC,\u7c7b\u4f3c\u4e8e\u7b2c\u4e00\u79cd,\u9002\u7528\u4e8e\u591aCPU,\u5e76\u8981\u6c42\u7f29\u77ed\u56e0GC\u9020\u6210\u7a0b\u5e8f\u505c\u6ede\u7684\u65f6\u95f4.\u8fd9\u79cdGC\u53ef\u4ee5\u5728Old\u533a\u7684<\/p>\n

\u56de\u6536\u540c\u65f6,\u8fd0\u884c\u5e94\u7528\u7a0b\u5e8f.-XX:+UseConcMarkSweepGC\u53c2\u6570\u542f\u52a8\u8be5GC.
\n\u7b2c\u56db\u79cd\uff1aIncremental Low Pause GC,\u9002\u7528\u4e8e\u8981\u6c42\u7f29\u77ed\u56e0GC\u9020\u6210\u7a0b\u5e8f\u505c\u6ede\u7684\u65f6\u95f4.\u8fd9\u79cdGC\u53ef\u4ee5\u5728Young\u533a\u56de\u6536\u7684\u540c\u65f6,\u56de\u6536<\/p>\n

\u4e00\u90e8\u5206Old\u533a\u5bf9\u8c61.-Xincgc\u53c2\u6570\u542f\u52a8\u8be5GC.
\n4\u79cdGC\u7684\u5177\u4f53\u63cf\u8ff0\u53c2\u89c1[3].
\n\u53c2\u8003\u6587\u7ae0:
\n1. JVM Tuning.<\/p>\n

http:\/\/www.caucho.com\/resin-3.0\/performance\/jvm-tuning.xtp#garbage-collection<\/a>
\n2. Performance tuning Java: Tuning steps
\nhttp:\/\/h21007.www2.hp.com\/dspp\/tech\/tech_TechDocumentDetailPage_IDX\/1,1701,1604,00.html<\/a>
\n3. Tuning Garbage Collection with the 1.4.2 JavaTM Virtual Machine .
\nhttp:\/\/java.sun.com\/docs\/hotspot\/gc1.4.2\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

\u5e38\u89c1\u914d\u7f6e\u4e3e\u4f8b\u00a0 \u5806\u5927\u5c0f\u8bbe\u7f6e JVM \u4e2d\u6700\u5927\u5806\u5927\u5c0f\u6709\u4e09\u65b9\u9762\u9650\u5236:\u76f8\u5173\u64cd\u4f5c\u7cfb\u7edf\u7684\u6570\u636e\u6a21\u578b(32-bt\u8fd8\u662f64-bit)\u9650\u5236;\u7cfb\u7edf\u7684\u53ef\u7528\u865a\u62df\u5185\u5b58\u9650\u5236;\u7cfb\u7edf\u7684\u53ef\u7528\u7269\u7406\u5185\u5b58\u9650\u5236.32\u4f4d\u7cfb\u7edf \u4e0b,\u4e00\u822c\u9650\u5236\u57281.5G~2G;64\u4e3a\u64cd\u4f5c\u7cfb\u7edf\u5bf9\u5185\u5b58\u65e0\u9650\u5236.\u6211\u5728Windows Server 2003 \u7cfb\u7edf,3.5G\u7269\u7406\u5185\u5b58,JDK5.0\u4e0b\u6d4b\u8bd5,\u6700\u5927\u53ef\u8bbe\u7f6e\u4e3a1478m. \u5178\u578b\u8bbe\u7f6e: java -Xmx3550m -Xms3550m -Xmn2g -Xss128k -Xmx3550m:\u8bbe\u7f6eJVM\u6700\u5927\u53ef\u7528\u5185\u5b58\u4e3a3550M. -Xms3550m:\u8bbe\u7f6eJVM\u4fc3\u4f7f\u5185\u5b58\u4e3a3550m.\u6b64\u503c\u53ef\u4ee5\u8bbe\u7f6e\u4e0e-Xmx\u76f8\u540c,\u4ee5\u907f\u514d\u6bcf\u6b21\u5783\u573e\u56de\u6536\u5b8c\u6210\u540eJVM\u91cd\u65b0\u5206\u914d\u5185\u5b58. -Xmn2g:\u8bbe\u7f6e\u5e74\u8f7b\u4ee3\u5927\u5c0f\u4e3a2G.\u6574\u4e2a\u5806\u5927\u5c0f=\u5e74\u8f7b\u4ee3\u5927\u5c0f + \u5e74\u8001\u4ee3\u5927\u5c0f + […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1022","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/blog.jsjs.org\/index.php?rest_route=\/wp\/v2\/posts\/1022","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.jsjs.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.jsjs.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.jsjs.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.jsjs.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1022"}],"version-history":[{"count":0,"href":"https:\/\/blog.jsjs.org\/index.php?rest_route=\/wp\/v2\/posts\/1022\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.jsjs.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1022"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.jsjs.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1022"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.jsjs.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1022"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}