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111 lines
3.7 KiB
111 lines
3.7 KiB
This is a KDE tool to assist with malloc debugging using glibc's "mtrace"
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functionality. Unfortunately the mtrace that is part of current (9/9/2000)
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glibc versions only logs the return-address of the malloc/free call.
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The file mtrace.c in this directory logs a complete backtrace upon malloc/
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free.
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THIS PROGRAM DEPENDS ON GLIBC! It does not pretend to be portable.
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Howto use:
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Install the libktrace.so shared library, the ktrace.h header file, the
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and kde.excludes file and the kmtrace processing tool with:
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make install
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There are two ways to activate memory usage loggings by ktrace :
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1) The LD_PRELOAD way
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This way, you can debug any application without having to recompile it,
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but you'll have to debug also the memory allocated by KApplication and
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friends.
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You can activate malloc logging by starting yourApplication as:
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MALLOC_TRACE=/tmp/ktrace.out LD_PRELOAD=/usr/lib/kmtrace/libktrace.so yourApplication
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2) The manual way
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Take the KDE application that you want to investigate and add
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#include <ktrace.h>
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Add as first statement in main():
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ktrace();
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Add ktrace_s.a to the LDADD line in your Makefile.am like:
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kicker_LDADD = kicker.la /usr/lib/kmtrace/libktrace_s.a
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Note that the static library is used.
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You can now activate malloc logging by starting yourApplication as:
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MALLOC_TRACE=/tmp/ktrace.out yourApplication
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This will generate a huge log in /tmp/ktrace.out.
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You can process this log with:
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kmtrace /tmp/ktrace.out > ktrace.parsed
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By default the trace-output is stored in the current directory
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as "ktrace.out". kmtrace also searches it there, so you don't need
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to add any commandline options.
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TIPS
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====
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* If you can't be bothered with the stuff that KApplication allocates for you
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you might want to put the ktrace() call after the KApplication constructor.
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This will lead to a lot of warnings like:
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Freeing unalloacted memory: 0x08056108
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Which are harmless, it just means that the memory was allocated before you
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turned the tracing on. Note that you cannot use this if you're using
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LD_PRELOAD to use ktrace.
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* To filter out harmless allocations out of the output file you can specify
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with the --exclude option a file with symbols to exclude from output. If a
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backtrace contains a symbol that starts with any of the symbols in this file,
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this backtrace / leaked block is not shown in the output.
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In the file kde.exclude some example symbols are listed. Usage example:
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kmtrace /tmp/malloc.trace > /tmp/malloc.parsed
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* Be aware that the reported symbols may not be accurate under all
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circumstances. E.g. consider the following backtrace:
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0x405879c1 /lib/libdl.so.2(dlerror+0x1b1)
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0x405873b3 /lib/libdl.so.2(dlopen+0x33)
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0x4053c0b2 /ext/kde2.0/lib/libkdecore.so.3(QXmlSimpleReader::reportParseErro
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0x4053c74b /ext/kde2.0/lib/libkdecore.so.3(lt_dlexit+0x24b)
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0x4053c894 /ext/kde2.0/lib/libkdecore.so.3(lt_dlexit+0x394)
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0x4053dd49 /ext/kde2.0/lib/libkdecore.so.3(lt_dlopen+0x899)
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The QXmlSimpleReader is obviously wrong here.
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* You can use the --tree option to kmtrace to specify a file to print a tree
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of the allocations. You can also use --treedepth and --treethreshold options
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to hide subtrees that are deeper than the specified depth or allocated less
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than the given memory amount.
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* The advantage of using libktrace_s.a (the static library) is that you can
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put calls to ktrace() and kuntrace() around a block of code that
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interests you. Only allocations and deallocations between the first call
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to ktrace() and the first call to kuntrace() will be logged.
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Have fun.
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Waldo Bastian
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bastian@kde.org
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kmtrace.cpp by Waldo Bastian <bastian@kde.org>
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ktrace.c by Waldo Bastian <bastian@kde.org> based on mtrace.c
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mtrace.c by Mike Haertel <mike@ai.mit.edu>
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mtrace.c patched by Andi Kleen <ak@suse.de>
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