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Command line HSDB
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<h1>Command line HSDB</h1>

When debugging remote core dumps it is easier to work with command line tools instead of
GUI tools. Command line HSDB (CLHSDB) tool is alternative to SA GUI tool HSDB.



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 with
support for output redirection/appending (familiar &gt;, &gt;&gt;), 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 source command.
help command prints usage message for all supported commands (or a specific command)


<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 turn on/off asserts in SA code
 attach pid | exec core | debugserver attach SA to a process, core, or remote debug server
 buildreplayjars [all | boot | app] build jars for replay, boot.jar for bootclasses, app.jar for application classes
 class name find a Java class from debuggee and print oop
 classes print all loaded Java classes with Klass*
 detach detach SA from current target
 dis address [ length ] disassemble (x86) specified number of instructions from given address
 dissemble address disassemble nmethod
 dumpcfg -a | id Dump the PhaseCFG for every compiler thread that has one live
 dumpclass { address | name } [ directory ] dump .class file for given Klass* or class name
 dumpcodecache dump codecache contents
 dumpheap [ file ] dump heap in hprof binary format
 dumpideal -a | id dump ideal graph like debug flag -XX:+PrintIdeal
 dumpilt -a | id dump inline tree for C2 compilation
 dumpreplaydata &lt;address&gt; | -a | &lt;thread_id&gt; [&gt;replay.txt] dump replay data into a file
 echo [ true | false ] turn on/off command echo mode
 examine [ address/count ] | [ address,address] show contents of memory from given address
 field [ type [ name fieldtype isStatic offset address ] ] print info about a field of HotSpot type
 findpc address print info about pointer location
 findsym name print address of symbol in the executable or shared library
 flags [ flag ] show all -XX flag name value pairs. or just show given flag
 help [ command ] print help message for all commands or just given command
 history show command history. usual !command-number syntax works.
 inspect expression inspect a given oop
 intConstant [ name [ value ] ] print out hotspot integer constant(s)
 jdis address show bytecode disassembly of a given Method*
 jhisto show Java heap histogram
 jseval script evaluate a given string as JavaScript code
 jsload file load and evaluate a JavaScript file
 jstack [-v] show Java stack trace of all Java threads. -v is verbose mode
 livenmethods show all live nmethods
 longConstant [ name [ value ] ] print out hotspot long constant(s)s
 mem address [ length ] show contents of memory -- also shows closest ELF/COFF symbol if found
 pmap show Solaris pmap-like output
 print expression print given Klass*, Method* or arbitrary address
 printas type expression print given address as given HotSpot type. eg. print JavaThread &lt;address&gt;
 printmdo -a | expression print method data oop
 printstatics [ type ] print static fields of given HotSpot type (or all types if none specified)
 pstack [-v] show mixed mode stack trace for all Java, non-Java threads. -v is verbose mode
 quit quit CLHSDB tool
 reattach detach and re-attach SA to current target
 revptrs find liveness of oops
 scanoops start end [ type ] scan a Oop from given start to end address
 search [ heap | codecache | threads ] value search a value in heap or codecache or threads
 source filename load and execute CLHSDB commands from given file
 symbol name show address of a given ELF/COFF symbol
 sysprops show all Java System properties
 thread id show thread of id
 threads show all Java threads
 tokenize ...
 type [ type [ name super isOop isInteger isUnsigned size ] ] show info. on HotSpot type
 universe print gc universe
 vmstructsdump dump hotspot type library in text
 verbose true | false turn on/off verbose mode
 versioncheck [ true | false ] turn on/off debuggee VM version check
 whatis address print info about any arbitrary address
 where { -a | id } print Java stack trace of given Java thread or all Java threads (-a)
</code>
</pre>

<h3>JavaScript integration</h3>

Few CLHSDB commands are already implemented in JavaScript. It is possible to extend CLHSDB command set
by implementing more commands in a JavaScript file and by loading it by jsload command. jseval
command may be used to evaluate arbitrary JavaScript expression from a string. Any JavaScript function
may be exposed as a CLHSDB command by registering it using JavaScript <code>registerCommand</code>
function. This function accepts command name, usage and name of the JavaScript implementation function
as arguments.


<h3>Simple CLHSDB command implemented in JavaScript</h3>

File: test.js
<pre>
<code>
function helloImpl(name) {
 println("hello, " + name);
}

// register the above JavaScript function as CLHSDB command
registerCommand("hello", "hello name", "helloImpl");
</code>
</pre>
--------- 

"test.js" can be loaded in CLHSDB prompt using jsload command using

<pre>
<code>
hsdb&gt; jsload test.js
</code>
</pre>

<h3>Compilation Replay</h3>

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>

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