Memory analysis tool for Android (memory analyzer tool)

Memory analysis tool for Android (memory analyzer tool)

If ddms does discover Memory leakage in our program, how can we locate the specific problematic code snippet and find the problem? If you analyze the code logic from start to end, it will drive people crazy, especially when maintaining the code written by others. Here is an excellent memory analysis tool-memory analyzer tool (MAT ).
MAT is an Eclipse plug-in with a separate RCP client. For more information, see www.eclipse.org/mat. In addition, there are complete tutorials in the help documentation after mat installation. Here, we will only illustrate how to use it. I use the mat Eclipse plug-in, which is easier to use than RCP.
Several steps are required to use mat for memory analysis, including generating the. hprof file, opening the mat and importing the. hprof file, and using the mat View tool to analyze the memory. The following is a detailed description.
(1) generate the. hprof File
Generate. there are many methods for hprof files, and they are generated in different Android versions. the hprof method is slightly different. I use version 2.1, which is generated in each version. for the prof file method, see:

Http://android.git.kernel.org /? P = platform/Dalvik. Git; A = blob_plain; F = docs/heap-profiling.html; HB = head.

1. Open eclipse and switch to the ddms perspective. Check that the devices, heap, and logcat views are enabled;
2. Link your phone to your computer and make sure that you use the "USB debug" mode instead of the "Mass Storage" mode;
3. After the connection is successful, the device serial number and some processes running on the device are displayed in the devices view;
4. Click the process of the application to be analyzed, and select the update heap and dump hprof file buttons in the icon button above the devices view;
5. this is where the ddms tool will automatically generate the currently selected process. hprof file, convert it, and store it in sdcard. If you have installed the mat plug-in, the mat will be automatically enabled and started. hprof file for analysis;
Note: Steps 4th and 5th can be used normally only when sdcard is available and the current process has the write permission (write_external_storage) to the sdcard. Otherwise. the hprof file will not be generated and will be displayed in logcat, such
Error/dalvikvm (8574): hprof: Can't open/sdcard/COM. XXX. hprof-hptemp: Permission denied.

.

If we do not have sdcard, or the current process does not have the permission to write data to sdcard (such as system_process), we can do this:
6. In the current program, for example, some code in the framework, you can use:
Public static void dumphprofdata (string filename) throws ioexception
Method to manually specify the location where the. hprof file is generated. For example:
Xxxbutton. setonclicklistener (New View. onclicklistener (){
Public void onclick (view ){
Android. OS. Debug. dumphprofdata ("/data/temp/MyApp. hprof ");
......
}
}
The above code is intended to capture memory usage information when xxxbutton is clicked and save it at our specified location:/data/temp/MyApp. hprof, so there is no permission restriction, and you do not need to use sdcard. Make sure that the/data/TEMP directory exists. This path can be defined by yourself, and can also be written as a path in sdcard.
 
(2) Use mat to import the. hprof File
1. If the. hprof file is automatically generated by ECLIPSE, you can use the mat plug-in to open it directly (it may be supported by a newer ADT );
2. if. the hprof file cannot be directly opened by mat, or android is used. OS. debug. manually generated by the dumphprofdata () method. hprof file, you need. to convert the hprof file, use the following method:
For example. copy the hprof file to the/android_sdk/tools directory on the PC, and enter the hprof-Conv XXX command. hprof yyy. hprof, where xxx. hprof is the original file, YYY. hprof is the converted file. The converted files are automatically stored in the/android_sdk/tools directory. OK. Till now, the. hprof file has been processed and can be used to analyze Memory leakage.
3. In eclipse, choose windows> open perspective> Other> memory analyzer, or press RCP of memory analyzer tool. In the mat, click File-> open file to browse and import the. hprof file just converted.
(3) Use Mat's View tool to analyze memory
Import. after the hprof file is created, the mat automatically parses and generates a report. Click dominator tree, group by package, and right-click the package class you have defined, select List objects-> with incoming references in the pop-up menu. All the suspicious classes are listed. Right-click an item and choose path to GC roots-> exclude weak/soft references, all classes related to the program with Memory leakage will be further filtered out. Based on this, we can track a class in the code that produces leakage.
Shows the mat interface.
 

The specific analysis method is not described here, because the help documents on the official website and client of Mat are very detailed.
It is important to understand the role of various views in mat, for example, introduced in www.eclipse.org/mat/about/screenshots.php.

In short, the fundamental idea of using mat to analyze the memory to find Memory leakage is to find out which class of object reference is not released, and find the reason why it is not released, in this way, you can easily locate the logic of the segments in the code.