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225 lines
6.9 KiB
HTML
225 lines
6.9 KiB
HTML
<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<meta name="GENERATOR" content="Mozilla/4.61 [en] (X11; I; Linux 2.2.5-22 i686) [Netscape]">
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<title>Leaky</title>
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<body text="#000000" bgcolor="#FFFFFF" link="#0000EE" vlink="#551A8B" alink="#FF0000">
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<center><b><font face="Arial,Helvetica"><font size=+2>Leaky</font></font></b></center>
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<p>Leaky is a program which will help you find memory leaks, and as of
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late, help you debug reference count problems with xpcom objects.
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<p><b><font face="Arial,Helvetica"><font size=+2>Get the Source</font></font></b>
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<p>Leaky is not currently part of the default SeaMonkey module,
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<br>you will need to explicitly pull the source:
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<br>
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<pre> cvs checkout mozilla/tools/leaky</pre>
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If there is enough demand, we can make this part of the default SeaMonkey
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module.
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<p><b><font face="Arial,Helvetica"><font size=+2>Building it</font></font></b>
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<br>
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<pre> ./configure --enable-leaky</pre>
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Top-of-tree build should Just Build It and leaky will show up in dist/bin.
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<p><b><font face="Arial,Helvetica"><font size=+2>Using Leaky</font></font></b>
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<p>After it has been built, you can use TestPreload and TestMalloc and
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ShowLibs to debug your implementation.
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<p>By setting the <tt>LIBMALLOC_LOG</tt> environment variable you control
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how much information is logged during the programs execution. See libmalloc.h
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for a definition of the values to use. If you are using <tt>LD_PRELOAD</tt>,
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here is one way to run your program:
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<blockquote><tt>env LD_PRELOAD=/full/path/to/libleaky.so LIBMALLOC_LOG=1
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my-program</tt></blockquote>
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The debugging malloc library creates two files, <tt>malloc-log</tt> and
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<tt>malloc-map</tt>.
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The malloc-log file can be quite large for large programs (e.g. mozilla)
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so be prepared to have alot of disk space. The malloc-map is tiny.
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<p>Once your program has completed execution you can use leaky to look
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for memory leaks, or at least use it to dump the log. For memory leaks,
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you use leaky like this:
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<blockquote><tt>leaky -d <program-name-goes-here> malloc-log</tt></blockquote>
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Leaky will then display all of the call sites where memory was leaked.
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To look at the entire log file contents, not just the leaks add "-a" to
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the arguments:
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<blockquote><tt>leaky -d -a <program-name-goes-here> malloc-log</tt></blockquote>
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For debugging reference count issues, here is what I do:
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<ol>
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<li>
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Set LIBMALLOC_LOG to "8"</li>
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<li>
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Modify your source code so that your class::Addref and class::Release methods
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call __log_addref and __log_release, as appropriate. See libmalloc.h for
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their signatures. If you are using mozilla, you no longer need to modify
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your source code with a debug build. See
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<a href="http://lxr.mozilla.org/seamonkey/source/xpcom/doc/MemoryTools.html">
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xpcom/doc/MemoryTools.html</a> for more info.
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</li>
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<li>
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Run your program so that you get the log data. Its often convenient to
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run your program in the debugger and then set a breakpoint at an interesting
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location where you think some object is being leaked or over-freed. Then
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when the debugger gets there tell it to execute DumpAddressMap. In gdb
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you do this:</li>
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<ol>
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<br><tt>(gdb) p DumpAddressMap()</tt></ol>
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<li>
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Then use leaky to capture the addref and release calls to a log file:</li>
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<ol>
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<br><tt>leaky -d -a <program-name-goes-here> malloc-log > log</tt></ol>
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<li>
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Then use "grep" to search the log for a specific object by grepping for
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its memory address...</li>
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<li>
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On a typical *short* run of mozilla, I'll end up with a malloc-log file
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of around 5 to 10 megabytes and the resulting converted log file will be
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10 to 20 times that so be prepared to have alot of disk space. It helps
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a great deal to narrow down your problem space to reduce the log file size...</li>
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</ol>
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<p><br>Leaky now has a "graph" output option. If you do this:
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<pre> leaky -gqx <program-name-goes-here> malloc-log | sed -e 's/&/&/g' > /tmp/GQ0.html</pre>
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Then leaky will make a graph of the leaks [-g] and output that graph in
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xml format (currently actually html...) [-x]. I use sed to make it legitimate
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html and off it goes to a file.
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<p>If you throw file at viewer (recursion is cool) then it will present
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you with a treeview of the leaks that you can click on to open/close sections.
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Enjoy!
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<p><b><font face="Arial,Helvetica"><font size=+2>Command Line Options</font></font></b>
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<br>
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<table CELLSPACING=5 CELLPADDING=0 WIDTH="100%" NOSAVE >
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<tr>
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<td>-a</td>
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<td>dump the entire log. This means all malloc's, free's, new's, delete's,
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addref's or release's will be displayed</td>
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</tr>
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<tr>
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<td>-d</td>
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<td>dump leaks (only one of -d, -R or -g can be used at a time)</td>
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</tr>
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<tr>
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<td>-R</td>
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<td>dump refcnts</td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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</tr>
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<tr>
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<td>-g</td>
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<td>display a graph of leaks</td>
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</tr>
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<tr>
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<td>-x</td>
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<td>when displaying the graph with -g, use html output that can be fed
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into an html4+css+dom compliant viewer (like mozilla :-)</td>
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</tr>
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<tr>
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<td>-r symbol</td>
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<td>define a root for the graph dump. nodes in the graph above symbol will
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be hidden, thus reducing the depth of the graph making it easier to find
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deeper leaks.</td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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</tr>
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<tr>
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<td>-e symbol</td>
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<td>exclude leaks that include symbol from treatment</td>
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</tr>
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<tr>
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<td>-i symbol</td>
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<td>include leaks that include symbol for treatment. If an includes are
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defined than only leaks which include the symbols will be processed. excludes
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will still apply to this reduced set of leaks</td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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</tr>
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<tr>
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<td>-A</td>
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<td>show the address in the stack crawls, not just the symobls</td>
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</tr>
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<tr>
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<td>-h num</td>
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<td>set the size of the hash buckets used by leaksy dictionaries to <num></td>
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</tr>
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<tr>
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<td>-s depth</td>
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<td>set the depth of the stack crawls shown when displaying stack crawls
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(any of the dumping modes except -g)</td>
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</tr>
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<tr>
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<td>-q</td>
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<td>make leaky quiet (don't dump the information about symbols being read
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and from which libraries)</td>
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</tr>
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</table>
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<p><b><font face="Arial,Helvetica"><font size=+2>Porting to non-Intel/Linux</font></font></b>
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<br>
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<p>Initial version works only on x86 linux. To work on other platforms
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you will need to:
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<ol>
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<li>
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Implement <tt>CrawlStack()</tt> in libmalloc.cpp</li>
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<li>
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Implement <tt>DumpAddressMap()</tt> in libmalloc.cpp and in ShowLibs.cpp</li>
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<li>
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Either support LD_PRELOAD in your dynamic linker, <b>or</b></li>
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<br>produce a library that wraps your libc malloc (see config.h for some
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clues)
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<li>
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Implement symbol table reading code (see coff.cpp, elf.cpp and bfd.cpp
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for examples; at the time of writing this document only bfd.cpp was known
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to work)</li>
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</ol>
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<hr><!-- hhmts start -->Last modified: Sun Sep 26 13:15:33 PDT 1999<!-- hhmts end -->
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<br>Send comments to <i><a href="mailto:kipp@netscape.com">Kipp Hickman</a></i>
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<br>
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</body>
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</html>
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