jvm-arguments

问题 The theoretical maximum heap value that can be set with -Xmx in a 32-bit system is of course 2^32 bytes, but typically (see: Understanding max JVM heap size - 32bit vs 64bit) one cannot use all 4GB. For a 64-bit JVM running in a 64-bit OS on a 64-bit machine, is there any limit besides the theoretical limit of 2^64 bytes or 16 exabytes? I know that for various reasons (mostly garbage collection), excessively large heaps might not be wise , but in light of reading about servers with terrabytes

问题 After reading already asked question on the subject and a lot of googling I am still not able to have a clear view of -Xms option My question is: what\'s the difference between java -Xms=512m -Xmx=512m and java -Xms=64m -Xmx=512m ? For now I have the following answer: The only difference is in the number of garbage collections that will be run during my application\'s run and the number of memory allocations. Am I right ? Here are my reasons for this answer: Setting the -Xms option to 512m

问题 Specifically, why would it help to fix a PermGen OutOfMemoryError issue? Also, bonus points for an answer that points me to the documentation on JVM arguments... 回答1: The permanent space is where the classes, methods, internalized strings, and similar objects used by the VM are stored and never deallocated (hence the name). This Oracle article succinctly presents the working and parameterization of the HotSpot GC and advises you to augment this space if you load many classes (this is

问题 I want to increase the available heap space for Jenkins. But as it is installed as a service I don´t know how to do it. 回答1: In your Jenkins installation directory there is a jenkins.xml, where you can set various options. Add the parameter -Xmx with the size you want to the arguments-tag (or increase the size if its already there). 回答2: If you used Aptitude (apt-get) to install Jenkins on Ubuntu 12.04, uncomment the JAVA_ARGS line in the top few lines of /etc/default/jenkins : # arguments to

问题 Normally to attach a debuger to a running jvm you would need start the jvm with arguments such as the following: > java -Xdebug -Xrunjdwp:transport=dt_socket,address=1000,server=y,suspend=n Now if I want to debug a process that wasn\'t started in debug mode, what can I do? This situation arrises when a production system (i.e. started without debug args) exhibits a \'random\' (I use the term loosely) bug. So I can\'t restart the jvm with the appropriate arguments, because nobody knows how to

问题 First of all, I have a box with 8gb of ram, so I doubt total memory is the issue. This application is running fine on machines with 6gb or less. I am trying to reserve 3GB of space using -Xmx3G under \"VM Arguments\" in Run Configurations in Eclipse. Every time I try to reserve more than 1500mb, I get this error: “Error occurred during initialization of VM; Could not reserve enough space for object heap” using -Xmx3G What is going on here? 回答1: Could it be that you're using a 32-bit jvm on

问题 I\'m using IDEA 12 Leda on Mountain Lion. I wanted to increase the maximum memory that IDE can use. I set the VMOptions in Info.plist file to be -Xmx2048m -ea -XX:+HeapDumpOnOutOfMemoryError -Xverify:none -Xbootclasspath/a:../lib/boot.jar When I open up IDEA, I still see the maximum memory to be 711m. jps -v shows my VMOptions has been loaded but it\'s replaced by the following options. 29388 **-Xmx2048m** -ea -XX:+HeapDumpOnOutOfMemoryError -Xverify:none -Xbootclasspath/a:../lib/boot.jar

问题 I need to run a Java memory intensive application that uses more than 2GB, but I am having problems to increase the heap maximum size. So far, I have tried the following approaches: Setting the -Xmx parameter, e.g. -Xmx3000m. This approaches fails at the creation of the JVM. From what I\'ve googled, it looks like that -Xmx must be less than 2GB. Using the -XX:+AggressiveHeap option. When I try this approach I get an \'Not enough memory\' error that tells that the heap size is 1273.4 MB, even

问题 I thought it would be great to have a comparison between _JAVA_OPTIONS and JAVA_TOOL_OPTIONS . I have been searching a bit for one, but I cannot find anything, so I hope we can find the knowledge here on Stackoverflow. JAVA_OPTS is included for completeness. It is not part of the JVM, but there is a lot of questions about it out in the wild. What I know: So far I have found out that: JAVA_OPTS is not used by the JDK, but by a bunch of other apps (see this post). JAVA_TOOL_OPTIONS and _JAVA

问题 I cannot for the life of me find a definition of what the Java VM flag CMSClassUnloadingEnabled actually does, other than some very fuzzy high-level definitions such as \"gets rid of your PermGen problems\" (which it doesn\'t, btw). I have looked on Sun\'s/Oracle\'s site, and even the options list doesn\'t actually say what it does. Based upon the name of the flag, I\'m guessing that the CMS Garbage Collector doesn\'t by default unload classes, and this flag turns it on - but I can\'t be sure