{"id":232,"date":"2009-10-16T08:15:26","date_gmt":"2009-10-16T08:15:26","guid":{"rendered":"https:\/\/kari.world.ikari.fi\/2009\/10\/16\/thanks-for-the-memory\/"},"modified":"2009-10-16T08:15:26","modified_gmt":"2009-10-16T08:15:26","slug":"thanks-for-the-memory","status":"publish","type":"post","link":"https:\/\/kari.world.ikari.fi\/?p=232","title":{"rendered":"Thanks for the memory"},"content":{"rendered":"

Thanks for the memory<\/a><\/p>\n

Some interesting points:<\/p>\n

1:<\/p>\n

\n… When a JVM’s Java heap is swapped out, the garbage collector’s performance becomes extremely poor, to the extent that the application can appear to hang. If multiple Java runtimes are in use on a single machine at the same time, the physical memory must be sufficient to fit all of the Java heaps. …\n<\/p><\/blockquote>\n

2:<\/p>\n

\n… Each Java thread requires stack space. Stack size varies among implementations, but with default settings, each thread could occupy up to 756KB of native memory. …\n<\/p><\/blockquote>\n

3:<\/p>\n

\n”Windows Java address space”<\/a> (Phil Vickers and Amar Devegowda, IBM Java Technology Centre, December 2005): Find out how to maximize the IBM Java memory address space on 32-bit Windows systems.<\/p>\n

\n… Recall that the Java heap must be a contiguous space and that its practical max size is around 1.5 GB. …<\/b>\n<\/p><\/blockquote>\n<\/blockquote>\n

Update: 5.12.2009<\/strong>
\nMysteries of ”cannot create new native thread”. Why such things occurs?<\/p>\n

Virtual Memory Usage from Java under Linux, too much memory used<\/a>
\nJava and default stack size for threads: 0.4MB, 1MB, or 8MB?<\/a>
\nUnderstanding ulimit output<\/a>
\nAre +”Xss” +”ThreadStackSize” the same?<\/a>
\nTroubleshooting Memory Leaks<\/a><\/p>\n

Quickly poking around, it appears that it would be usefull to peek into pmap<\/code> output for process. In my linux box it appears that ”pmap -x PID | grep 308 | wc -l” corresponds very closely into amount of threads in application (308 being memory allocated to some mysterious ”anon”, actually there is 12 + 308 per thread in pmap).<\/p>\n

So it looks like in this system, each thread is consuming 320 KB of native memory. However, interestingly, after some tens of threads had been terminated in java, these 12+308 blocks of memory still haven’t been released. Is that some memory leak bug in Sun 1.6.0 JVM?<\/p>\n

Update: 13.3.2010<\/strong>
\nMemory Leak Detection & Memory Diagnosis<\/a>
\nDas Java Memory Modell (1. Akt)<\/a><\/p>\n

Update: 12.6.2010<\/strong>
\nJava Memeory Overview Public<\/a>
\nEclipse MemoryAnalyzer<\/a>
\nFinding PermGen Memory Leaks with YourKit<\/a>
\nInside The Jvm Memory Management And Troubleshooting<\/a>
\nOutOfMemoryError (on HeapSpace, PermGen) and JVM Performance Tuning<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Thanks for the memory Some interesting points: 1: … When a JVM’s Java heap is swapped out, the garbage collector’s performance becomes extremely poor, to the extent that the application can appear to hang. If multiple Java runtimes are in use on a single machine at the same time, the physical memory must be sufficient…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-232","post","type-post","status-publish","format-standard","hentry","category-java"],"_links":{"self":[{"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=\/wp\/v2\/posts\/232","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=232"}],"version-history":[{"count":0,"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=\/wp\/v2\/posts\/232\/revisions"}],"wp:attachment":[{"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=232"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=232"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=232"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}