The reason we got this error is a bug in Windows Server 2008 R2 / Windows 7. The kernel leaks loopback sockets due to a race condition on machines with more than one core, this patch fixes the issue: http://support.microsoft.com/kb/2577795
Update: This answer was originally written in 2014 and is obsolete. Peter ‘s answer is correct in that -Xms is allocated at startup and it will grow up to -Xmx (max heap size) but it’s a little misleading in how he has worded his answer. (Sorry Peter I know you know this stuff cold). Setting … Read more
I think that the answer is “Yes”. This probably as good as you can do in Java using system independent code. But be aware that even this is only relatively system independent. For example, in some systems: the JAVA_HOME variable may not have been set, the command name used to launch a JVM might be … Read more
Do it like: java -Xms256m -Xmx512m -Djava.awt.headless=true -jar filename.jar
What I don’t understand is that since JVM is essentially a software, how are those JVM heap, stack and threads mapped to physical machine? The heap is a pre-allocated continuous region of virtual memory. e.g. void* heap = malloc(Xmx); // get the maximum size. The stacks are allocated by the threading library when the thread … Read more
JAVA_OPTS is the standard environment variable that some servers and other java apps append to the call that executes the java command. For example in tomcat if you define JAVA_OPTS=’-Xmx1024m’, the startup script will execute java org.apache.tomcat.Servert -Xmx1024m If you are running in Linux/OSX, you can set the JAVA_OPTS, right before you call the startup … Read more
A couple of things, first will be flushed to memory – that’s pretty erroneous. It’s almost never a flush to main memory – it usually drains the StoreBuffer to L1 and it’s up to the cache coherency protocol to sync the data between all caches, but if it’s easier for you to understand this concept … Read more
It’s so easy to get fooled by hand-made microbenchmarks – you never know what they actually measure. That’s why there are special tools like JMH. But let’s analyze what happens to the primitive hand-made benchmark: static class HDouble { double value; } public static void main(String[] args) { primitive(); wrapper(); } public static void primitive() … Read more
JVM_FindSignal does not allocate memory at all. And this function is not typically called often at application run-time. It seems your JDK installation does not include debug symbols, so that jemalloc profiler cannot find the correct function name and just takes the nearest public symbol from libjvm.so. JVM_FindSignal is just one of these random symbols. … Read more
Yes you can. 1) Inject a DLL in the process hosting the JVM (eg, java.exe, or javaw.exe, or iexplore.exe). A common injection technique is to use SetWindowsHookEx 2) In the DLL, get the module handle of the jvm.dll using GetModuleHandle 3) Get the address of the JNI_GetCreatedJavaVMs function, using GetProcAddress 4) Call the function and, … Read more