RSCr.png' alt='Simple Rmi Program Using Netbeans Java' title='Simple Rmi Program Using Netbeans Java' />Frequently Asked Questions About the Java Hot. Spot VM This FAQ answers common questions about Java Hot. Spot Technology and about performance in general. Unless otherwise noted, all information on this page applies to both the Hot. Spot Client VM and the Hot. Spot Server VM as of Java SE version 1. General. What command line options does the Java Hot. Spot VM provide for performance tuning Are there any resources for troubleshooting Hot. Spot issues I cant get profiling to work, what should I doI keep running out of file descriptors, what should I do Memory and Garbage Collection. Pause times are unnecessarily long, what parameters can I use to tune this How do I profile heap usageThe VM prints Out. Of. Memory. Error and exits. Increasing max heap size doesnt help. Whats going on Why cant I get a larger heap with the 3. JVM Should I pool objects to help GC Should I call System. What determines when softly referenced objects are flushed Im getting lots of full GCs when I turn on verbose gc at regular intervals, Ive tuned the heap and it makes no difference, whats going onJIT Compiler. Whats the difference between the client and server systems Where do I get the server and client systems I would like java to default to server. I have a lot of scripts which I cannot change or do not want to change. Is there any way to do thisShould I warm up my loops first so that Hotspot will compile them Java. What is 6. 4 bit Java Which platforms and Java releases support 6. LZtsv.png' alt='Simple Rmi Program Using Netbeans Java' title='Simple Rmi Program Using Netbeans Java' />This is a list of TCP and UDP port numbers used by protocols of the transport layer of the Internet protocol suite for the establishment of hosttohost connectivity. This is an excellent guideline for servletmapping please also give me more information about jsp, java collection rmi. Simple Rmi Program Using Netbeans Java' title='Simple Rmi Program Using Netbeans Java' />Where can I download the 6. SDK or JRE When you download the SDK or JRE, must you choose between the 3. How do I select between 3. Whats the default Are both client and server VM modes available in 6. JMSProducer/images/t10102.gif' alt='Simple Rmi Program Using Netbeans Java' title='Simple Rmi Program Using Netbeans Java' />Java Which components do not support 6. How is native code affected When writing Java code, how do I distinguish between 3. Will 3. 2 bit native code work with a 6. VMs Where can I learn more about 6. What are the performance characteristics of 6. VMs What are the default heap sizes for 6. VMs if GC ergonomics is not usedHow large a heap can I create using a 6. VM Which garbage collector should I use for very large 6. Multithreaded Applications. Serial Dilution Sources Of Error In Measurement. I have a program which uses a lot of threads and it runs slow. My application has a lot of threads and is running out of memory, why Which thread library should I use on Solaris 8 What options do I need in order to use the alternate one to one thread model on Solaris 8 or 9 How does the JVM map priorities for Java threads onto native thread priorities in Solaris Performance. My application runs slowly. Why My program isnt scaling with the number of processors. How many processors will the Hot. Spot VM scale toMy server application isnt getting faster, why IO is a problem, why My application uses a database and doesnt seem to scale well. What could be going onBenchmarking the Java Hot. Spot VMI write a simple loop to time a simple operation and its slow. What am I doing wrong Heres my program. Im trying to time method invocation time. I dont want there to be any extra work done, so Im using an empty method. But when I run with Hot. Spot I get times that are unbelievably fast. Okay, so Ill put some random code in the body of the method so its not empty and the inlining cant just remove it. Heres my new method. Im trying to benchmark object allocation and garbage collection. So I have harness. I have a graphics intensive or GUI based program. Why doesnt Hot. Spot making my graphics code go faster What do you recommend for benchmarking Hot. Spot, or any virtual machine General. What command line options does the Java Hot. Spot VM provide for performance tuning See the document Java Hot. Spot VM Options. Are there any resources for troubleshooting Hot. Spot issues For more in depth troubleshooting discussion beyond the scope of this FAQ, please see the Java Trouble Shooting and Diagnostic Guide. I cant get profiling to work, what should I doFirst, make sure you are running with agentlib hprof and try agentlib hprofhelp to see the different kinds of profiling available. If you are still having problems please see the Java Trouble Shooting and Diagnostic Guide. I keep running out of file descriptors, what should I doCertain applications will use a lot of file descriptors. The only thing that you can do is to set the number of file descriptors allowed on the system higher. The hard limit default is 1. To set this higher you need to modify etcsystem by adding the following 2 definitions. Memory and Garbage Collection. Pause times are unnecessarily long, what parameters can I use to tune thisThere are several things to try in this arena. First, give Xincgc a try. This uses the incremental garbage collection algorithm, which attempts to collect a fraction of the heap instead of the entire thing at once. For most programs this results in shorter pauses, although throughput is usually worse. Next, you might try decreasing the amount of heap used. A larger heap will cause garbage collection pauses to increase because there is more heap to scan. Try Xmx. If your application requires more memory than you can adjust the size of the eden young generation space with XX New. Size. and XX Max. Heartstrings Korean Drama Episode 1 Eng Sub Download there. New. Size. for 1. Xmn in 1. 4 and later. For some applications a very large eden helps, for others it will increase the times of minor collections. For most programs, collecting eden is much faster than other generations because most objects die young. If you currently invoke with something like. Xms. 38. 4m Xmx. XX New. Size1. 28m XX Max. New. Size1. 28m. For 1. Max. New. Size is set to 3. Sparc, 2. 5mb on Intel based machines. New. Ratio the ratio between the youngold generations has values of 2 on Sparc Server, 1. Intel, and 8 everywhere else, as you can quickly determine, this is superseded by Max. New. Sizes defaults rendering New. Ratio ineffective for even moderately sized heaps. In 1. 4 and later, Max. New. Size has been effectively set to infinity, and New. Ratio can be used instead to set the value of the new generation. Using the above as an example, you can do the following in 1. Xms. 38. 4m Xmx. XX New. Ratio2. If you are worried about the number of garbage collections, but less worried about pause times, then increasing the heap should cause the number of full garbage collections to decrease, this is especially true if you increase the size of the eden space as well. Many systems have less efficient memory management than in Hot. Spot. To work around this, some programs keep an object pool, saving previously allocated objects in some freelist like data structure and reusing them instead of allocating new ones. But. Dont use object poolsUsing object pools will fool the collector into thinking objects are live when they really arent. This may have worked before exact garbage collection became popular, but this is just not a good idea for any modern Java Virtual Machines. See also Tuning Garbage Collection with the 5. Java Virtual Machine. How do I profile heap usageTry using Xaprof to get a profile of the allocations objects and sizes of your application. You can also try agentlib hprofheapall or other option, try agentlib hprofhelp for a listSince 1. For more information, see jmap Memory Map and Java Trouble Shooting and Diagnostic Guide. The VM prints Out. Of. Memory. Error and exits. Increasing max heap size doesnt help. Whats going on The Java Hot.