jvm-hotspot

I've just downloaded Oracle's Server JRE for Java SE 7 ( link ) The file I downloaded was server-jre-7u45-linux-x64.tar.gz . When I extracted this file I was surprised to find a directory named jdk1.7.0_45 was created containing the full java JDK. Not what I expected from a JRE install. What is going on here? The answer is in the description of the packages on the parent page: JDK: (Java Development Kit). For Java Developers. Includes a complete JRE plus tools for developing, debugging, and monitoring Java applications. Server JRE: (Server Java Runtime Environment) For deploying Java

Why does this code sometimes produce ArrayOutOfBoundsException? How is that even possible for String.valueOf(int) ? public static String ipToString(ByteString bs) { if (bs == null || bs.isEmpty()) { return null; } else { StringBuilder sb = new StringBuilder(); boolean started = false; for (Byte byt : bs) { if (started) { sb.append("."); } sb.append(String.valueOf(byt & 0xFF)); started = true; } return sb.toString(); } } java.lang.ArrayIndexOutOfBoundsException: -81914 at java.lang.Integer.getChars(Integer.java:458) at java.lang.Integer.toString(Integer.java:402) at java.lang.String.valueOf

I got the below assembly list as result for JIT compilation for my java program. mov 0x14(%rsp),%r10d inc %r10d mov 0x1c(%rsp),%r8d inc %r8d test %eax,(%r11) ; <--- this instruction mov (%rsp),%r9 mov 0x40(%rsp),%r14d mov 0x18(%rsp),%r11d mov %ebp,%r13d mov 0x8(%rsp),%rbx mov 0x20(%rsp),%rbp mov 0x10(%rsp),%ecx mov 0x28(%rsp),%rax movzbl 0x18(%r9),%edi movslq %r8d,%rsi cmp 0x30(%rsp),%rsi jge 0x00007fd3d27c4f17 My understanding the test instruction is useless here because the main idea of the test is The flags SF, ZF, PF are modified while the result of the AND is discarded. and here we don't

It annoys me every time I use -XX:+PrintAssembly with Hotspot and have to read the horrible AT&T syntax. Is there a way to tell it to use the Intel syntax? All you need is to parse some options onto the dis-asm.h and binutils code For intel Asm (which I also prefer) just add the following -XX:PrintAssemblyOptions=intel If you need to combine options do it with commas like so -XX:PrintAssemblyOptions=intel,hsdis-help Anything not recognised as a hsdis option will be fed to the disassembler, these options are the same ones you see listed from objdump --help ... <SNIP A lot of --help text %<> ...

Why does Java , running in -server mode, say that the version is "mixed-mode" ? When I see that, does it mean that the JVM didn't truly load in pure server mode? server mode does not mean "not mixed". Those are different settings. Mixed does mean that the JVM will mix compiled and interpreted code. You could optionally switch to fully interpreted mode with the switch -Xint (usually you don't want to do this). Server mode means that the hot-spot-compiler will run with server-settings. The general assumption is that VMs in server-mode are long-running, so optimizations will be done with this in

Im curious what the exact meaning of "committed" memory is when the value is queried from the MemoryUsage class. That class explains it as "committed represents the amount of memory (in bytes) that is guaranteed to be available for use by the Java virtual machine." Does this mean that the memory is in use by the jvm process and NOT available to other processes until it is released by the java process, or does it mean that the java process will be successful if it tries to allocate up to that amount of memory? I realize this might be implementation specific but i am only interested in hotspot.