8066013: (prefs) Unused variable in src/java.prefs/share/classes/java/util/prefs/MacOSXPreferences.java
Summary: Two unused variables in MacOSXPreferences.java were removed
Reviewed-by: cbensen, psandoz, chegar
Contributed-by: steve.drach@oracle.com
<html><head><title>Command line HSDB</title></head><body><h1>Command line HSDB</h1><p>When debugging remote core dumps it is easier to work with command line tools instead ofGUI tools. Command line HSDB (CLHSDB) tool is alternative to SA GUI tool HSDB.</p><p>There is also JavaScript based SA command line interface called <a href="jsdb.html">jsdb</a>.But, CLHSDB supports Unix shell-like (or dbx/gdb-like) command line interface withsupport for output redirection/appending (familiar >, >>), command history and so on.Each CLHSDB command can have zero or more arguments and optionally end with output redirection(or append) to a file. Commands may be stored in a file and run using <b>source</b> command.<b>help</b> command prints usage message for all supported commands (or a specific command)</p><h3>Shell/batch scripts to run command line HSDB</h3><ul><li>clhsdbproc.sh<li>clhsdbproc64.sh<li>clhsdbwindbg.bat<li>clhsdbwindbg64.bat</ul><h3>Annotated output of CLHSDB help command</h3><pre><code>Available commands: assert true | false <font color="red">turn on/off asserts in SA code</font> attach pid | exec core <font color="red">attach SA to a process or core</font> buildreplayjars [all | boot | app] <font color="red">build jars for replay, boot.jar for bootclasses, app.jar for application classes</font> class name <font color="red">find a Java class from debuggee and print oop</font> classes <font color="red">print all loaded Java classes with Klass*</font> detach <font color="red">detach SA from current target</font> dis address [ length ] <font color="red">disassemble (sparc/x86) specified number of instructions from given address</font> dissemble address <font color="red">disassemble nmethod</font> dumpcfg -a | id <font color="red">Dump the PhaseCFG for every compiler thread that has one live</font> dumpclass { address | name } [ directory ] <font color="red">dump .class file for given Klass* or class name</font> dumpcodecache <font color="red">dump codecache contents</font> dumpheap [ file ] <font color="red">dump heap in hprof binary format</font> dumpideal -a | id <font color="red">dump ideal graph like debug flag -XX:+PrintIdeal</font> dumpilt -a | id <font color="red">dump inline tree for C2 compilation</font> dumpreplaydata <address> | -a | <thread_id> [>replay.txt] <font color="red">dump replay data into a file</font> echo [ true | false ] <font color="red">turn on/off command echo mode</font> examine [ address/count ] | [ address,address] <font color="red">show contents of memory from given address</font> field [ type [ name fieldtype isStatic offset address ] ] <font color="red">print info about a field of HotSpot type</font> findpc address <font color="red">print info. about pointer location</font> flags [ flag ] <font color="red">show all -XX flag name value pairs. or just show given flag</font> help [ command ] <font color="red">print help message for all commands or just given command</font> history <font color="red">show command history. usual !command-number syntax works.</font> inspect expression <font color="red">inspect a given oop</font> intConstant [ name [ value ] ] <font color="red">print out hotspot integer constant(s)</font> jdis address <font color="red">show bytecode disassembly of a given Method*</font> jhisto <font color="red">show Java heap histogram</font> jseval script <font color="red">evaluate a given string as JavaScript code</font> jsload file <font color="red">load and evaluate a JavaScript file</font> jstack [-v] <font color="red">show Java stack trace of all Java threads. -v is verbose mode</font> livenmethods <font color="red">show all live nmethods</font> longConstant [ name [ value ] ] <font color="red">print out hotspot long constant(s)s</font> mem address [ length ] <font color="red">show contents of memory -- also shows closest ELF/COFF symbol if found</font> pmap <font color="red">show Solaris pmap-like output</font> print expression <font color="red">print given Klass*, Method* or arbitrary address</font> printas type expression <font color="red">print given address as given HotSpot type. eg. print JavaThread <address></font> printmdo -a | expression <font color="red">print method data oop</font> printstatics [ type ] <font color="red">print static fields of given HotSpot type (or all types if none specified)</font> pstack [-v] <font color="red">show mixed mode stack trace for all Java, non-Java threads. -v is verbose mode</font> quit <font color="red">quit CLHSDB tool</font> reattach <font color="red">detach and re-attach SA to current target</font> revptrs <font color="red">find liveness of oops</font> scanoops start end [ type ] <font color="red">scan a Oop from given start to end address</font> search [ heap | codecache | threads ] value <font color="red">search a value in heap or codecache or threads</font> source filename <font color="red">load and execute CLHSDB commands from given file</font> symbol name <font color="red">show address of a given ELF/COFF symbol</font> sysprops <font color="red">show all Java System properties</font> thread id <font color="red">show thread of id</font> threads <font color="red">show all Java threads</font> tokenize ... type [ type [ name super isOop isInteger isUnsigned size ] ] <font color="red">show info. on HotSpot type</font> universe <font color="red">print gc universe</font> vmstructsdump <font color="red">dump hotspot type library in text</font> verbose true | false <font color="red">turn on/off verbose mode</font> versioncheck [ true | false ] <font color="red">turn on/off debuggee VM version check</font> whatis address <font color="red">print info about any arbitrary address</font> where { -a | id } <font color="red">print Java stack trace of given Java thread or all Java threads (-a)</font></code></pre><h3>JavaScript integration</h3><p>Few CLHSDB commands are already implemented in JavaScript. It is possible to extend CLHSDB command setby implementing more commands in a JavaScript file and by loading it by <b>jsload</b> command. <b>jseval</b>command may be used to evaluate arbitrary JavaScript expression from a string. Any JavaScript functionmay be exposed as a CLHSDB command by registering it using JavaScript <b><code>registerCommand</code></b>function. This function accepts command name, usage and name of the JavaScript implementation functionas arguments.</p><h3>Simple CLHSDB command implemented in JavaScript</h3><b>File: test.js</b><pre><code>function helloImpl(name) { println("hello, " + name);}// register the above JavaScript function as CLHSDB commandregisterCommand("hello", "hello name", "helloImpl");</code></pre>---------<br>"test.js" can be loaded in CLHSDB prompt using <b>jsload</b> command using<pre><code>hsdb> jsload test.js</code></pre><h3>Compilation Replay</h3><p>When a java process crashes in compiled method, usually a core file is saved.The replay function can reproduce the compiling process in the core.<a href="cireplay.html">cireplay.html</a></body></html>