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Finding Memory Leaks: Difference between revisions
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→Configuring Address Sanitizer
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== Building Octave == | == Building Octave == | ||
Creating a version of Octave which works with an Address Sanitizer is quite simple. After obtaining the source code for Octave, use the configure script with whatever options you normally build with and add the special option | Creating a version of Octave which works with an Address Sanitizer is quite simple. After obtaining the source code for Octave, use the configure script with whatever options you normally build with and add the special option <code>--enable-address-sanitizer-flags</code>. In addition, it is often very very useful for the backtraces if debugging information is included during the build. As an example of configuring Octave for finding memory leaks | ||
<syntaxhighlight lang="bash"> | |||
setenv CFLAGS "-ggdb3 -O0 -pipe" | |||
setenv CXXFLAGS "${CFLAGS}" | |||
setenv FFLAGS "${CFLAGS}" | |||
./configure --prefix=/home/user/local --enable-address-sanitizer-flags -C | |||
</syntaxhighlight> | |||
==== GUI leaks ==== | ==== GUI leaks ==== | ||
If there is a memory problem, the Address Sanitizer will dump information about the leak, including a backtrace, to stderr. However, if you are using the GUI it will have redirected stderr so that it no longer shows up in the terminal window from which Octave was launched. In order to debug the GUI, temporarily undo this redirection by commenting out lines 117-119 in libgui/qterminal/libqterminal/unix/QUnixTerminalImpl.cpp. The patch to do so is shown below. Copy this to a file and then execute | If there is a memory problem, the Address Sanitizer will dump information about the leak, including a backtrace, to stderr. However, if you are using the GUI it will have redirected stderr so that it no longer shows up in the terminal window from which Octave was launched. In order to debug the GUI, temporarily undo this redirection by commenting out lines 117-119 in {{path|libgui/qterminal/libqterminal/unix/QUnixTerminalImpl.cpp}}. The patch to do so is shown below. Copy this to a file and then execute <code>patch -p1 < dup.patch</code>. | ||
{{file|dup.patch| | |||
<syntaxhighlight lang="diff"> | |||
diff -r f50ef29d874e libgui/qterminal/libqterminal/unix/QUnixTerminalImpl.cpp | |||
--- a/libgui/qterminal/libqterminal/unix/QUnixTerminalImpl.cpp Thu Sep 14 09:02:07 2017 -0700 | |||
+++ b/libgui/qterminal/libqterminal/unix/QUnixTerminalImpl.cpp Thu Sep 14 09:40:07 2017 -0700 | |||
@@ -114,9 +114,11 @@ void QUnixTerminalImpl::connectToPty() | |||
int fds = m_kpty->slaveFd(); | |||
+ /* | |||
dup2 (fds, STDIN_FILENO); | |||
dup2 (fds, STDOUT_FILENO); | |||
dup2 (fds, STDERR_FILENO); | |||
+ */ | |||
if(!isatty(STDIN_FILENO)) { | |||
qDebug("Error: stdin is not a tty."); | |||
</syntaxhighlight> | |||
}} | |||
After patching the code, build as before with the correct configure options and then proceed normally. The GUI will run, but the Command Window will now appear back in the terminal window from which you launched Octave. | After patching the code, build as before with the correct configure options and then proceed normally. The GUI will run, but the Command Window will now appear back in the terminal window from which you launched Octave. | ||
| Line 36: | Line 42: | ||
== Configuring Address Sanitizer == | == Configuring Address Sanitizer == | ||
The Address Sanitizer is now built in to the Octave executable. The behavior of the Sanitizer can be controlled with the environment variable | The Address Sanitizer is now built in to the Octave executable. The behavior of the Sanitizer can be controlled with the environment variable '''ASAN_OPTIONS'''. For example, this is a useful value of ASAN_OPTIONS: | ||
<syntaxhighlight lang="bash"> | |||
setenv ASAN_OPTIONS "leak_check_at_exit=0:verbosity=1" | |||
</syntaxhighlight> | |||
This stops reporting on any leaks at the end of the program, as those will be cleaned up by the operating system anyways when the process itself is destroyed. | This stops reporting on any leaks at the end of the program, as those will be cleaned up by the operating system anyways when the process itself is destroyed. | ||
Another useful option is "log_file=my-log-file-name". By default, a process ID is appended to the log-file name. | |||
== Finding Leaks == | == Finding Leaks == | ||
Now that Octave has been built with the Address Sanitizer, and the Sanitizer itself has been configured by its environment variable, the next step is to launch Octave (typically ./run-octave), and execute code. This might mean running the default set of tests that come with Octave, | Now that Octave has been built with the Address Sanitizer, and the Sanitizer itself has been configured by its environment variable, the next step is to launch Octave (typically <code>./run-octave</code>), and execute code. This might mean running the default set of tests that come with Octave, <code>__run_test_suite__</code>. It could mean a particular function, "test ls". Or it could be simply running your own scripts, commands, etc. to see if a leak is triggered. If a memory error is detected the Sanitizer will dump a summary and backtrace to stderr. Make a new bug report at http://bugs.octave.org and include the backtrace in the report. | ||
[[Category:Development]] | |||