{"id":32759,"date":"2023-02-01T15:19:28","date_gmt":"2023-02-01T09:49:28","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-best-java-code-to-control-big-heap-memeory-used-like-1g-closed\/"},"modified":"2023-02-01T15:19:28","modified_gmt":"2023-02-01T09:49:28","slug":"solved-best-java-code-to-control-big-heap-memeory-used-like-1g-closed","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-best-java-code-to-control-big-heap-memeory-used-like-1g-closed\/","title":{"rendered":"[Solved] best Java code to control big heap memeory used (like 1G) [closed]"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-32624124\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"32624124\" data-parentid=\"32623675\" data-score=\"3\" data-position-on-page=\"1\" data-highest-scored=\"1\" data-question-has-accepted-highest-score=\"1\" itemprop=\"acceptedAnswer\" itemscope itemtype=\"https:\/\/schema.org\/Answer\">\n<div class=\"post-layout\">\n<div class=\"votecell post-layout--left\"><\/div>\n<div class=\"answercell post-layout--right\">\n<div class=\"s-prose js-post-body\" itemprop=\"text\">\n<p>Quickly allocate 1 GB of memory:<\/p>\n<pre><code>byte[][] memoryWaster = new byte[1024][1_048_576];\n<\/code><\/pre>\n<p>See last test run below for successful allocation of <strong>16 GB<\/strong> of memory.<\/p>\n<p><em>Test program<\/em><\/p>\n<pre><code>Runtime runtime = Runtime.getRuntime();\nSystem.out.printf(\"total: %11d   max: %d%n\", runtime.totalMemory(), runtime.maxMemory());\nSystem.out.printf(\"used:  %11d%n\", runtime.totalMemory() - runtime.freeMemory());\nSystem.gc();\nSystem.out.printf(\"gc:    %11d%n\", runtime.totalMemory() - runtime.freeMemory());\nbyte[][] memoryWaster = new byte[1024][1_048_576];\nmemoryWaster[0][0] = 2; \/\/ prevent unused warning\nSystem.out.printf(\"new[]: %11d%n\", runtime.totalMemory() - runtime.freeMemory());\nSystem.gc();\nSystem.out.printf(\"gc:    %11d%n\", runtime.totalMemory() - runtime.freeMemory());\nmemoryWaster = null;\nSystem.out.printf(\"null:  %11d%n\", runtime.totalMemory() - runtime.freeMemory());\nSystem.gc();\nSystem.out.printf(\"gc:    %11d%n\", runtime.totalMemory() - runtime.freeMemory());\n<\/code><\/pre>\n<p><em>Output<\/em> (Java 8, 32-bit):<\/p>\n<pre><code>\/\/ Java 1.8.0_51, 32-bit, no -Xmx given\ntotal:    16252928   max: 259522560\nused:       543288\ngc:         349296\nException in thread \"main\" java.lang.OutOfMemoryError: Java heap space\n        at test.Test.main(Test.java:11)\n\n\/\/ Java 1.8.0_51, 32-bit, -Xmx1200m\ntotal:    16252928   max: 1216348160\nused:       543288\ngc:         349296\nnew[]:  1078435312\ngc:     1078382592\nnull:   1078382592\ngc:       15711288\n\n\/\/ Java 1.8.0_51, 64-bit, no -Xmx given, 32 GB machine\ntotal:   514850816   max: 7618953216\nused:      5389872\ngc:        2981048\nnew[]:  1074961632\ngc:     1081175720\nnull:   1081175720\ngc:       13027424\n\n\/\/ Java 1.8.0_51, 64-bit, -Xmx1200m\ntotal:   514850816   max: 1118830592\nused:      5389872\ngc:        2981048\nnew[]:  1077948560\ngc:     1078944096\nnull:   1078944096\ngc:        3501136\n\n\/\/ Java 1.8.0_51, 64-bit, -Xmx20g, new byte[16384][1_048_576]\ntotal:   514850816   max: 19088801792\nused:      5389872\ngc:        2981048\nnew[]: 17205604928\ngc:    17205604928\nnull:  17205604928\ngc:       26186032\n<\/code><\/pre>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">2<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved best Java code to control big heap memeory used (like 1G) [closed] <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] Quickly allocate 1 GB of memory: byte[][] memoryWaster = new byte[1024][1_048_576]; See last test run below for successful allocation of 16 GB of memory. Test program Runtime runtime = Runtime.getRuntime(); System.out.printf(&#8220;total: %11d max: %d%n&#8221;, runtime.totalMemory(), runtime.maxMemory()); System.out.printf(&#8220;used: %11d%n&#8221;, runtime.totalMemory() &#8211; runtime.freeMemory()); System.gc(); System.out.printf(&#8220;gc: %11d%n&#8221;, runtime.totalMemory() &#8211; runtime.freeMemory()); byte[][] memoryWaster = new byte[1024][1_048_576]; memoryWaster[0][0] = &#8230; <a title=\"[Solved] best Java code to control big heap memeory used (like 1G) [closed]\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-best-java-code-to-control-big-heap-memeory-used-like-1g-closed\/\" aria-label=\"More on [Solved] best Java code to control big heap memeory used (like 1G) [closed]\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[378,323],"class_list":["post-32759","post","type-post","status-publish","format-standard","hentry","category-solved","tag-heap-memory","tag-java"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] best Java code to control big heap memeory used (like 1G) [closed] - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-best-java-code-to-control-big-heap-memeory-used-like-1g-closed\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] best Java code to control big heap memeory used (like 1G) [closed] - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] Quickly allocate 1 GB of memory: byte[][] memoryWaster = new byte[1024][1_048_576]; See last test run below for successful allocation of 16 GB of memory. Test program Runtime runtime = Runtime.getRuntime(); System.out.printf(&quot;total: %11d max: %d%n&quot;, runtime.totalMemory(), runtime.maxMemory()); System.out.printf(&quot;used: %11d%n&quot;, runtime.totalMemory() - runtime.freeMemory()); System.gc(); System.out.printf(&quot;gc: %11d%n&quot;, runtime.totalMemory() - runtime.freeMemory()); byte[][] memoryWaster = new byte[1024][1_048_576]; memoryWaster[0][0] = ... 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Test program Runtime runtime = Runtime.getRuntime(); System.out.printf(\"total: %11d max: %d%n\", runtime.totalMemory(), runtime.maxMemory()); System.out.printf(\"used: %11d%n\", runtime.totalMemory() - runtime.freeMemory()); System.gc(); System.out.printf(\"gc: %11d%n\", runtime.totalMemory() - runtime.freeMemory()); byte[][] memoryWaster = new byte[1024][1_048_576]; memoryWaster[0][0] = ... 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