Android
android.os
public final class

android.os.Debug

java.lang.Object
android.os.Debug

Provides various debugging functions for Android applications, including tracing and allocation counts.

Logging Trace Files

Debug can create log files that give details about an application, such as a call stack and start/stop times for any running methods. See Running the Traceview Debugging Program for information about reading trace files. To start logging trace files, call one of the startMethodTracing() methods. To stop tracing, call stopMethodTracing().

Nested Classes
Debug.InstructionCount API for gathering and querying instruction counts. 
Debug.MemoryInfo This class is used to retrieved various statistics about the memory mappings for this process. 

Summary

Constants

      Value  
int  SHOW_CLASSLOADER    0x00000002 
int  SHOW_FULL_DETAIL  Flags for printLoadedClasses().  0x00000001 
int  SHOW_INITIALIZED    0x00000004 
int  TRACE_COUNT_ALLOCS  Flags for startMethodTracing().  0x00000001 

Public Methods

      static    void  changeDebugPort(int port)
Change the JDWP port -- this is a temporary measure.
      static    void  enableEmulatorTraceOutput()
Enable "emulator traces", in which information about the current method is made available to the "emulator -trace" feature.
    final  static    int  getBinderDeathObjectCount()
Returns the number of death notification links to Binder objects that exist in the current process.
    final  static    int  getBinderLocalObjectCount()
Returns the number of active local Binder objects that exist in the current process.
    final  static    int  getBinderProxyObjectCount()
Returns the number of references to remote proxy Binder objects that exist in the current process.
      static    int  getBinderReceivedTransactions()
Returns the number of received transactions from the binder driver.
      static    int  getBinderSentTransactions()
Returns the number of sent transactions from this process.
      static    int  getGlobalAllocCount()
      static    int  getGlobalAllocSize()
      static    int  getGlobalExternalAllocCount()
      static    int  getGlobalExternalAllocSize()
      static    int  getGlobalExternalFreedCount()
      static    int  getGlobalExternalFreedSize()
      static    int  getGlobalFreedCount()
      static    int  getGlobalFreedSize()
      static    int  getGlobalGcInvocationCount()
      static    int  getLoadedClassCount()
Get the number of loaded classes.
      static    void  getMemoryInfo(Debug.MemoryInfo memoryInfo)
Retrieves information about this processes memory usages.
      static    long  getNativeHeapAllocatedSize()
Returns the amount of allocated memory in the native heap.
      static    long  getNativeHeapFreeSize()
Returns the amount of free memory in the native heap.
      static    long  getNativeHeapSize()
Returns the size of the native heap.
      static    int  getThreadAllocCount()
      static    int  getThreadAllocSize()
      static    int  getThreadExternalAllocCount()
      static    int  getThreadExternalAllocSize()
      static    int  getThreadGcInvocationCount()
      static    boolean  isDebuggerConnected()
Determine if a debugger is currently attached.
      static    void  printLoadedClasses(int flags)
Dump a list of all currently loaded class to the log file.
      static    void  resetAllCounts()
      static    void  resetGlobalAllocCount()
      static    void  resetGlobalAllocSize()
      static    void  resetGlobalExternalAllocCount()
      static    void  resetGlobalExternalAllocSize()
      static    void  resetGlobalExternalFreedCount()
      static    void  resetGlobalExternalFreedSize()
      static    void  resetGlobalFreedCount()
      static    void  resetGlobalFreedSize()
      static    void  resetGlobalGcInvocationCount()
      static    void  resetThreadAllocCount()
      static    void  resetThreadAllocSize()
      static    void  resetThreadExternalAllocCount()
      static    void  resetThreadExternalAllocSize()
      static    void  resetThreadGcInvocationCount()
      static    int  setAllocationLimit(int limit)
Establish an object allocation limit in the current thread.
      static    int  setGlobalAllocationLimit(int limit)
Establish a global object allocation limit.
      static    void  startAllocCounting()
Count the number and aggregate size of memory allocations between two points.
      static    void  startMethodTracing(String traceName)
Start method tracing, specifying the trace log file name.
      static    void  startMethodTracing(String traceName, int bufferSize)
Start method tracing, specifying the trace log file name and the buffer size.
      static    void  startMethodTracing(String traceName, int bufferSize, int flags)
Start method tracing, specifying the trace log file name and the buffer size.
      static    void  startMethodTracing()
Start method tracing with default log name and buffer size.
      static    void  startNativeTracing()
Enable qemu tracing.
      static    void  stopAllocCounting()
      static    void  stopMethodTracing()
Stop method tracing.
      static    void  stopNativeTracing()
Stop qemu tracing.
      static    long  threadCpuTimeNanos()
Get an indication of thread CPU usage.
      static    void  waitForDebugger()
Wait until a debugger attaches.
      static    boolean  waitingForDebugger()
Returns "true" if one or more threads is waiting for a debugger to attach.
Methods inherited from class java.lang.Object

Details

Constants

public static final int SHOW_CLASSLOADER

Constant Value: 2 (0x00000002)

public static final int SHOW_FULL_DETAIL

Flags for printLoadedClasses(). Default behavior is to only show the class name.
Constant Value: 1 (0x00000001)

public static final int SHOW_INITIALIZED

Constant Value: 4 (0x00000004)

public static final int TRACE_COUNT_ALLOCS

Flags for startMethodTracing(). These can be ORed together. TRACE_COUNT_ALLOCS adds the results from startAllocCounting to the trace key file.
Constant Value: 1 (0x00000001)

Public Methods

public static void changeDebugPort(int port)

Change the JDWP port -- this is a temporary measure. If a debugger is currently attached the change may not happen until after the debugger disconnects.

public static void enableEmulatorTraceOutput()

Enable "emulator traces", in which information about the current method is made available to the "emulator -trace" feature. There is no corresponding "disable" call -- this is intended for use by the framework when tracing should be turned on and left that way, so that traces captured with F9/F10 will include the necessary data. This puts the VM into "profile" mode, which has performance consequences. To temporarily enable tracing, use startNativeTracing().

public static final int getBinderDeathObjectCount()

Returns the number of death notification links to Binder objects that exist in the current process.

public static final int getBinderLocalObjectCount()

Returns the number of active local Binder objects that exist in the current process.

public static final int getBinderProxyObjectCount()

Returns the number of references to remote proxy Binder objects that exist in the current process.

public static int getBinderReceivedTransactions()

Returns the number of received transactions from the binder driver.

Returns

  • The number of received transactions or -1 if it could not read the stats.

public static int getBinderSentTransactions()

Returns the number of sent transactions from this process.

Returns

  • The number of sent transactions or -1 if it could not read t.

public static int getGlobalAllocCount()

public static int getGlobalAllocSize()

public static int getGlobalExternalAllocCount()

public static int getGlobalExternalAllocSize()

public static int getGlobalExternalFreedCount()

public static int getGlobalExternalFreedSize()

public static int getGlobalFreedCount()

public static int getGlobalFreedSize()

public static int getGlobalGcInvocationCount()

public static int getLoadedClassCount()

Get the number of loaded classes.

Returns

  • the number of loaded classes.

public static void getMemoryInfo(Debug.MemoryInfo memoryInfo)

Retrieves information about this processes memory usages. This information is broken down by how much is in use by dalivk, the native heap, and everything else.

public static long getNativeHeapAllocatedSize()

Returns the amount of allocated memory in the native heap.

Returns

  • The allocated size in bytes.

public static long getNativeHeapFreeSize()

Returns the amount of free memory in the native heap.

Returns

  • The freed size in bytes.

public static long getNativeHeapSize()

Returns the size of the native heap.

Returns

  • The size of the native heap in bytes.

public static int getThreadAllocCount()

public static int getThreadAllocSize()

public static int getThreadExternalAllocCount()

public static int getThreadExternalAllocSize()

public static int getThreadGcInvocationCount()

public static boolean isDebuggerConnected()

Determine if a debugger is currently attached.

public static void printLoadedClasses(int flags)

Dump a list of all currently loaded class to the log file.

Parameters

flags See constants above.

public static void resetAllCounts()

public static void resetGlobalAllocCount()

public static void resetGlobalAllocSize()

public static void resetGlobalExternalAllocCount()

public static void resetGlobalExternalAllocSize()

public static void resetGlobalExternalFreedCount()

public static void resetGlobalExternalFreedSize()

public static void resetGlobalFreedCount()

public static void resetGlobalFreedSize()

public static void resetGlobalGcInvocationCount()

public static void resetThreadAllocCount()

public static void resetThreadAllocSize()

public static void resetThreadExternalAllocCount()

public static void resetThreadExternalAllocSize()

public static void resetThreadGcInvocationCount()

public static int setAllocationLimit(int limit)

Establish an object allocation limit in the current thread. Useful for catching regressions in code that is expected to operate without causing any allocations. Pass in the maximum number of allowed allocations. Use -1 to disable the limit. Returns the previous limit. The preferred way to use this is: int prevLimit = -1; try { prevLimit = Debug.setAllocationLimit(0); ... do stuff that's not expected to allocate memory ... } finally { Debug.setAllocationLimit(prevLimit); } This allows limits to be nested. The try/finally ensures that the limit is reset if something fails. Exceeding the limit causes a dalvik.system.AllocationLimitError to be thrown from a memory allocation call. The limit is reset to -1 when this happens. The feature may be disabled in the VM configuration. If so, this call has no effect, and always returns -1.

public static int setGlobalAllocationLimit(int limit)

Establish a global object allocation limit. This is similar to setAllocationLimit(int) but applies to all threads in the VM. It will coexist peacefully with per-thread limits. [ The value of "limit" is currently restricted to 0 (no allocations allowed) or -1 (no global limit). This may be changed in a future release. ]

public static void startAllocCounting()

Count the number and aggregate size of memory allocations between two points. The "start" function resets the counts and enables counting. The "stop" function disables the counting so that the analysis code doesn't cause additional allocations. The "get" function returns the specified value. Counts are kept for the system as a whole and for each thread. The per-thread counts for threads other than the current thread are not cleared by the "reset" or "start" calls.

public static void startMethodTracing(String traceName)

Start method tracing, specifying the trace log file name. The trace file will be put under "/sdcard" unless an absolute path is given. See Running the Traceview Debugging Program for information about reading trace files.

Parameters

traceName Name for the trace log file to create. If no name argument is given, this value defaults to "/sdcard/dmtrace.trace". If the files already exist, they will be truncated. If the trace file given does not end in ".trace", it will be appended for you.

public static void startMethodTracing(String traceName, int bufferSize)

Start method tracing, specifying the trace log file name and the buffer size. The trace files will be put under "/sdcard" unless an absolute path is given. See Running the Traceview Debugging Program for information about reading trace files.

Parameters

traceName Name for the trace log file to create. If no name argument is given, this value defaults to "/sdcard/dmtrace.trace". If the files already exist, they will be truncated. If the trace file given does not end in ".trace", it will be appended for you.
bufferSize The maximum amount of trace data we gather. If not given, it defaults to 8MB.

public static void startMethodTracing(String traceName, int bufferSize, int flags)

Start method tracing, specifying the trace log file name and the buffer size. The trace files will be put under "/sdcard" unless an absolute path is given. See Running the Traceview Debugging Program for information about reading trace files.

When method tracing is enabled, the VM will run more slowly than usual, so the timings from the trace files should only be considered in relative terms (e.g. was run #1 faster than run #2). The times for native methods will not change, so don't try to use this to compare the performance of Java and native implementations of the same method. As an alternative, consider using "native" tracing in the emulator via startNativeTracing().

Parameters

traceName Name for the trace log file to create. If no name argument is given, this value defaults to "/sdcard/dmtrace.trace". If the files already exist, they will be truncated. If the trace file given does not end in ".trace", it will be appended for you.
bufferSize The maximum amount of trace data we gather. If not given, it defaults to 8MB.

public static void startMethodTracing()

Start method tracing with default log name and buffer size. See Running the Traceview Debugging Program for information about reading these files. Call stopMethodTracing() to stop tracing.

public static void startNativeTracing()

Enable qemu tracing. For this to work requires running everything inside the qemu emulator; otherwise, this method will have no effect. The trace file is specified on the command line when the emulator is started. For example, the following command line
emulator -trace foo
will start running the emulator and create a trace file named "foo". This method simply enables writing the trace records to the trace file.

The main differences between this and startMethodTracing() are that tracing in the qemu emulator traces every cpu instruction of every process, including kernel code, so we have more complete information, including all context switches. We can also get more detailed information such as cache misses. The sequence of calls is determined by post-processing the instruction trace. The qemu tracing is also done without modifying the application or perturbing the timing of calls because no instrumentation is added to the application being traced.

One limitation of using this method compared to using startMethodTracing() on the real device is that the emulator does not model all of the real hardware effects such as memory and bus contention. The emulator also has a simple cache model and cannot capture all the complexities of a real cache.

public static void stopAllocCounting()

public static void stopMethodTracing()

Stop method tracing.

public static void stopNativeTracing()

Stop qemu tracing. See startNativeTracing() to start tracing.

Tracing can be started and stopped as many times as desired. When the qemu emulator itself is stopped then the buffered trace records are flushed and written to the trace file. In fact, it is not necessary to call this method at all; simply killing qemu is sufficient. But starting and stopping a trace is useful for examining a specific region of code.

public static long threadCpuTimeNanos()

Get an indication of thread CPU usage. The value returned indicates the amount of time that the current thread has spent executing code or waiting for certain types of I/O. The time is expressed in nanoseconds, and is only meaningful when compared to the result from an earlier call. Note that nanosecond resolution does not imply nanosecond accuracy. On system which don't support this operation, the call returns -1.

public static void waitForDebugger()

Wait until a debugger attaches. As soon as the debugger attaches, this returns, so you will need to place a breakpoint after the waitForDebugger() call if you want to start tracing immediately.

public static boolean waitingForDebugger()

Returns "true" if one or more threads is waiting for a debugger to attach.
Copyright 2007 Google Inc. Build 0.9_r1-98467 - 14 Aug 2008 18:56