NAME¶
ddms - a graphical debugging tool for Android
SYNOPSIS¶
ddms
DESCRIPTION¶
Dalvik Debug Monitor Service (DDMS) provides port-forwarding services, screen
capture on the device, thread and heap information on the device, logcat,
process, and radio state information, incoming call and SMS spoofing, location
data spoofing, and more. This page provides a modest discussion of DDMS
features; it is not an exhaustive exploration of all the features and
capabilities.
DDMS will work with both the emulator and a connected device. If both are
connected and running simultaneously, DDMS defaults to the emulator.
How DDMS works¶
DDMS acts as a middleman to connect the IDE to the applications running on the
device. On Android, every application runs in its own process, each of which
hosts its own virtual machine (VM). And each process listens for a debugger on
a different port.
When it starts, DDMS connects to adb and starts a device monitoring service
between the two, which will notify DDMS when a device is connected or
disconnected. When a device is connected, a VM monitoring service is created
between adb and DDMS, which will notify DDMS when a VM on the device is
started or terminated. Once a VM is running, DDMS retrieves the the VM's
process ID (pid), via adb, and opens a connection to the VM's debugger,
through the adb daemon (adbd) on the device. DDMS can now talk to the VM using
a custom wire protocol.
For each VM on the device, DDMS opens a port upon which it will listen for a
debugger. For the first VM, DDMS listens for a debugger on port 8600, the next
on 8601, and so on. When a debugger connects to one of these ports, all
traffic is forwarded between the debugger and the associated VM. Debugging can
then process like any remote debugging session.
DDMS also opens another local port, the DDMS "base port" (8700, by
default), upon which it also listens for a debugger. When a debugger connects
to this base port, all traffic is forwarded to the VM currently selected in
DDMS, so this is typically where you debugger should connect.
Tip: You can set a number of DDMS preferences in File > Preferences.
Preferences are saved to "$HOME/.ddmsrc".
Known debugging issues with Dalvik
Debugging an application in the Dalvik VM should work the same as it does in
other VMs. However, when single-stepping out of synchronized code, the
"current line" cursor may jump to the last line in the method for
one step.
Left Pane¶
The left side of the Debug Monitor shows each emulator/device currently found,
with a list of all the VMs currently running within each. VMs are identified
by the package name of the application it hosts.
Use this list to find and attach to the VM running the activity(ies) that you
want to debug. Next to each VM in the list is a "debugger
pass-through" port (in the right-most column). If you connect your
debugger to one of the the ports listed, you will be connected to the
corresponding VM on the device. However, when using DDMS, you need only
connect to port 8700, as DDMS forwards all traffic here to the currently
selected VM. (Notice, as you select a VM in the list, the listed port includes
8700.) This way, there's no need to reconfigure the debugger's port each time
you switch between VMs.
When an application running on the device calls
waitForDebugger() (or you
select this option in the developer options), a red icon will be shown next to
the client name, while it waits for the debugger to attach to the VM. When a
debugger is connected, the icon will turn green.
If you see a crossed-out bug icon, this means that the DDMS was unable to
complete a connection between the debugger and the VM because it was unable to
open the VM's local port. If you see this for all VMs on the device, it is
likely because you have another instance of DDMS running (this includes the
Eclipse plugin).
If you see a question mark in place of an application package, this means that,
once DDMS received the application pid from adb, it somehow failed to make a
successful handshake with the VM process. Try restarting DDMS.
Right pane¶
On the right side, the Debug Monitor provides tabs that display useful
information and some useful tools.
Info¶
This view shows some general information about the selected VM, including the
process ID, package name, and VM version.
Threads¶
The threads view has a list of threads running in the process of the target VM.
To reduce the amount of data sent over the wire, the thread updates are only
sent when explicitly enabled by toggling the "threads" button in the
toolbar. This toggle is maintained per VM. This tab includes the following
information:
ID a VM-assigned unique thread ID. In Dalvik, these are odd numbers
starting from 3.
Tid the Linux thread ID. For the main thread in a process, this will
match the process ID.
Status the VM thread status. Daemon threads are shown with an asterisk
(*). This will be one of the following:
running - executing application code
sleeping - called Thread.sleep()
monitor - waiting to acquire a monitor lock
wait - in Object.wait()
native - executing native code
vmwait - waiting on a VM resource
zombie - thread is in the process of dying
init - thread is initializing (you shouldn't see this)
starting - thread is about to start (you shouldn't see this either)
utime cumulative time spent executing user code, in "jiffies"
(usually 10ms). Only available under Linux.
stime cumulative time spent executing system code, in "jiffies"
(usually 10ms).
Name the name of the thread
"ID" and "Name" are set when the thread is started. The
remaining fields are updated periodically (default is every 4 seconds).
VM Heap¶
Displays some heap stats, updated during garbage collection. If, when a VM is
selected, the VM Heap view says that heap updates are not enabled, click the
"Show heap updates" button, located in the top-left toolbar. Back in
the VM Heap view, click Cause GC to perform garbage collection and update the
heap stats.
Allocation Tracker¶
In this view, you can track the memory allocation of each virtual machine. With
a VM selected in the left pane, click Start Tracking, then Get Allocations to
view all allocations since tracking started. The table below will be filled
with all the relevant data. Click it again to refresh the list.
Emulator Control¶
With these controls, you can simulate special device states and activities.
Features include:
Telephony Status change the state of the phone's Voice and Data plans
(home, roaming, searching, etc.), and simulate different kinds of network
Speed and Latency (GPRS, EDGE, UTMS, etc.).
Telephony Actions perform simulated phone calls and SMS messages to the
emulator.
Location Controls send mock location data to the emulator so that you can
perform location-aware operations like GPS mapping.
To use the Location Controls, launch your application in the Android emulator
and open DDMS. Click the Emulator Controls tab and scroll down to Location
Controls. From here, you can:
- -
- Manually send individual longitude/latitude coordinates to the device.
Click Manual, select the coordinate format, fill in the fields and click
Send.
- -
- Use a GPX file describing a route for playback to the device.
Click GPX and load the file. Once loaded, click the play button to playback
the route for your location-aware application.
When performing playback from GPX, you can adjust the speed of playback from
the DDMS panel and control playback with the pause and skip buttons. DDMS
will parse both the waypoints (<wpt>, in the first table), and the
tracks (<trk>, in the second table, with support for multiple
segments, <trkseg>, although they are simply concatenated). Only the
tracks can be played. Clicking a waypoint in the first list simply sends
its coordinate to the device, while selecting a track lets you play
it.
- -
- Use a KML file describing individual placemarks for sequenced playback to
the device.
Click KML and load the file. Once loaded, click the play button to send the
coordinates to your location-aware application.
When using a KML file, it is parsed for a <coordinates> element. The
value of which should be a single set of longitude, latitude and altitude
figures. For example:
<coordinates>-122.084143,37.421972,4</coordinates>
In your file, you may include multiple <Placemark> elements, each
containing a <coordinates> element. When you do so, the collection
of placemarks will be added as tracks. DDMS will send one placemark per
second to the device.
Note: DDMS does not support routes created with the
<MultiGeometry><LineString>lat1, long1, lat2, long2,
...</LineString></MultiGeometry> methods. There is also
currently no support for the <TimeStamp> node inside the
<Placemark>. Future releases may support timed placement and routes
within a single coordinate element.
File Explorer¶
With the File Explorer, you can view the device file system and perform basic
management, like pushing and pulling files. This circumvents using the adb
push and pull commands, with a GUI experience.
With DDMS open, select Device > File Explorer... to open the File Explorer
window. You can drag-and-drop into the device directories, but cannot drag out
of them. To copy files from the device, select the file and click the Pull
File from Device button in the toolbar. To delete files, use the Delete button
in the toolbar.
If you're interested in using an SD card image on the emulator, you're still
required to use the mksdcard command to create an image, and then mount it
during emulator bootup. For example, from the /tools directory, execute:
$ mksdcard 1024M ./img $ emulator -sdcard ./img
Now, when the emulator is running, the DDMS File Explorer will be able to read
and write to the sdcard directory. However, your files may not appear
automatically. For example, if you add an MP3 file to the sdcard, the media
player won't see them until you restart the emulator. (When restarting the
emulator from command line, be sure to mount the sdcard again.)
Screen Capture¶
You can capture screen images on the device or emulator by selecting Device >
Screen capture... in the menu bar, or press CTRL-S.
Exploring Processes¶
You can see the output of ps -x for a specific VM by selecting Device > Show
process status... in the menu bar.
Cause a GC to Occur¶
Cause garbage collection to occury by pressing the trash can button on the
toolbar.
Running Dumpsys and Dumpstate on the Device (logcat)¶
To run dumpsys (logcat) from Dalvik, select Device > Run logcat... in the
menu bar.
To run dumpstate from Dalvik, select Device > Dump device state... in the
menu bar.
Examine Radio State¶
By default, radio state is not output during a standard logcat (it is a lot of
information). To see radio information, either click Device > Dump radio
state... or run logcat as described in Logging Radio Information.
Stop a Virtual Machine¶
You can stop a virtual machine by selecting Actions > Halt VM. Pressing this
button causes the VM to call
System.exit(1).
KNOWN ISSUES¶
If you connect and disconnect a debugger, ddms drops and reconnects the client
so the VM realizes that the debugger has gone away. This will be fixed
eventually.
COPYRIGHT¶
This manual page is licensed under the Apache License, Version 2.0.
Copyright (C) 2013 www.linuxtopia.org
Copyright (C) 2013 Jakub Adam <jakub.adam@ktknet.cz>