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Update malloc debug documentation.

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Test: NA
Change-Id: I8ab73bfc28c7a673efb5b0cec6067989153f092a
This commit is contained in:
Christopher Ferris 2017-05-24 19:04:33 -07:00
parent 1143a62977
commit 4c65669ab7
1 changed files with 44 additions and 12 deletions
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56
libc/malloc_debug/README.md
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@ -396,22 +396,27 @@ Enable multiple options (backtrace and guards):
adb shell setprop libc.debug.malloc.options "\"backtrace guards\""
adb shell start
Enable malloc debug when multiple processes have the same name. This method
can be used to enable malloc debug for only a very specific process if
multiple processes have the same name.
Note: The two levels of quoting in the adb shell command is necessary.
The outer layer of quoting is for the shell on the host, to ensure that the
inner layer of quoting is sent to the device, to make 'backtrace guards'
a single argument.
Note: The double quotes in the adb shell command are necessary. Otherwise,
the setprop command will fail since the backtrace guards options will look
like two arguments instead of one.
Enable malloc debug using an environment variable (pre-O Android release):
adb shell
# setprop libc.debug.malloc.env_enabled
# setprop libc.debug.malloc.env_enabled 1
# setprop libc.debug.malloc.options backtrace
# export LIBC_DEBUG_MALLOC_ENABLE 1
# export LIBC_DEBUG_MALLOC_ENABLE=1
# ls
Enable malloc debug and dump the native allocation with backtraces to
a file. This only works for zygote based java processes.
Enable malloc debug using an environment variable (Android O or later):
adb shell
# export LIBC_DEBUG_MALLOC_OPTIONS=backtrace
# ls
Any process spawned from this shell will run with malloc debug enabled
using the backtrace option.
adb shell stop
adb shell setprop libc.debug.malloc.options backtrace
@ -419,5 +424,32 @@ a file. This only works for zygote based java processes.
adb shell am dumpheap -n <PID_TO_DUMP> /data/local/tmp/heap.txt
It is possible to use the backtrace\_enable\_on\_signal option as well,
but it must be enabled through the signal before the file will contain
any data.
but, obviously, it must be enabled through the signal before the file will
contain any data.
To analyze the data produced by the dumpheap command, run this script:
development/scripts/native_heapdump_viewer.py
In order for the script to properly symbolize the stacks in the file,
make sure the script is executed from the tree that built the image.
Below is an example of how to execute the script using the dump created by the
above command:
adb shell pull /data/local/tmp/heap.txt .
development/scripts/native_heapdump_viewer.py heap.txt > heap_info.txt
Enable malloc debug for a specific program/application (Android O or later):
adb shell setprop wrap.<APP> '"LIBC_DEBUG_MALLOC_OPTIONS=backtrace logwrapper"'
For example, to enable malloc debug for the google search box (Android O or later):
adb shell setprop wrap.com.google.android.googlequicksearchbox '"LIBC_DEBUG_MALLOC_OPTIONS=backtrace logwrapper"'
adb shell am force-stop com.google.android.googlequicksearchbox
NOTE: On pre-O versions of the Android OS, property names had a length limit
of 32. This meant that to create a wrap property with the name of the app, it
was necessary to truncate the name to fit. On O, property names can be
an order of magnitude larger, so there should be no need to truncate the name
at all.