1 page.title=Profiling with Traceview and dmtracedump 2 parent.title=Debugging 3 parent.link=index.html 4 @jd:body 5 6 <div id="qv-wrapper"> 7 <div id="qv"> 8 <h2>In this document</h2> 9 10 <ol> 11 <li> 12 <a href="#traceviewLayout">Traceview Layout</a> 13 14 <ol> 15 <li><a href="#timelinepanel">Timeline Panel</a></li> 16 17 <li><a href="#profilepanel">Profile Panel</a></li> 18 </ol> 19 </li> 20 21 <li><a href="#creatingtracefiles">Creating Trace Files</a></li> 22 23 <li><a href="#copyingfiles">Copying Trace Files to a Host Machine</a></li> 24 25 <li><a href="#runningtraceview">Viewing Trace Files in Traceview</a></li> 26 27 <li><a href="#dmtracedump">Using dmtracedump</a></li> 28 29 <li><a href="#knownissues">Traceview Known Issues</a></li> 30 </ol> 31 </div> 32 </div> 33 34 <p>Traceview is a graphical viewer for execution logs that you create by using the {@link 35 android.os.Debug} class to log tracing information in your code. Traceview can help you debug 36 your application and profile its performance.</p> 37 38 <h2 id="traceviewLayout">Traceview Layout</h2> 39 40 <p>When you have a trace log file (generated by adding tracing code to your application or by DDMS), 41 you can have Traceview load the log files and display their data in a window visualizes your application 42 in two panels:</p> 43 44 <ul> 45 <li>A <a href="#timelinepanel">timeline panel</a> -- describes when each thread and method 46 started and stopped</li> 47 48 <li>A <a href="#timelinepanel">profile panel</a> -- provides a summary of what happened inside 49 a method</li> 50 </ul> 51 52 <p>The sections below provide addition information about the traceview output panes.</p> 53 54 <h3 id="timelinepanel">Timeline Panel</h3> 55 56 <p>The image below shows a close up of the timeline panel. Each thread’s execution is shown 57 in its own row, with time increasing to the right. Each method is shown in another color (colors 58 are reused in a round-robin fashion starting with the methods that have the most inclusive time). 59 The thin lines underneath the first row show the extent (entry to exit) of all the calls to the 60 selected method. The method in this case is <code>LoadListener.nativeFinished()</code> and it was selected in 61 the profile view.</p> 62 63 <img src="{@docRoot}images/traceview_timeline.png" 64 alt="Traceview timeline panel" 65 width="893" 66 height="284" /> 67 <p class="img-caption"><strong>Figure 1.</strong> The Traceview Timeline Panel</p> 68 69 <h3 id="profilepanel">Profile Panel</h3> 70 71 <p>Figure 2 shows the profile pane, a summary of all the time spent 72 in a method. The table shows both the inclusive and exclusive times (as well as the percentage of 73 the total time). Exclusive time is the time spent in the method. Inclusive time is the time spent 74 in the method plus the time spent in any called functions. We refer to calling methods as 75 "parents" and called methods as "children." When a method is selected (by clicking on it), it 76 expands to show the parents and children. Parents are shown with a purple background and children 77 with a yellow background. The last column in the table shows the number of calls to this method 78 plus the number of recursive calls. The last column shows the number of calls out of the total 79 number of calls made to that method. In this view, we can see that there were 14 calls to 80 <code>LoadListener.nativeFinished();</code> looking at the timeline panel shows that one of those calls took 81 an unusually long time.</p> 82 83 <img src="{@docRoot}images/traceview_profile.png" 84 alt="Traceview profile panel." 85 width="892" 86 height="630" /> 87 <p class="img-caption"><strong>Figure 2.</strong> The Traceview Profile Panel</p> 88 89 <h2 id="creatingtracefiles">Creating Trace Files</h2> 90 91 <p>To use Traceview, you need to generate log files containing the trace information you want to 92 analyze.</p> 93 94 <p>There are two ways to generate trace logs:</p> 95 <ul> 96 <li>Include the {@link android.os.Debug} class in your code and call its 97 methods to start and stop logging of trace information to disk. This method is very precise because 98 you can specify in your code exactly where to start and stop logging trace data.</li> 99 <li>Use the method profiling feature of DDMS to generate trace logs. This method is less 100 precise since you do not modify code, but rather specify when to start and stop logging with 101 a DDMS. Although you have less control on exactly where the data is logged, this method is useful 102 if you don't have access to the application's code, or if you do not need the precision of the first method. 103 </li> 104 </ul> 105 106 <p>Before you start generating trace logs, be aware of the following restrictions:</p> 107 <ul> 108 <li>If you are using the {@link android.os.Debug} class, your device or emulator must have an SD card 109 and your application must have permission to write to the SD card. </li> 110 <li>If you are using DDMS, Android 2.1 and earlier devices must 111 have an SD card present and your application must have permission to write to the SD card. 112 <li>If you are using DDMS, Android 2.2 and later devices do not need an SD card. The trace log files are 113 streamed directly to your development machine.</li> 114 </ul> 115 116 <p>This document focuses on using the {@link android.os.Debug} class to generate trace data. For more information on using DDMS 117 to generate trace data, see <a href="ddms.html#profiling">Using the Dalvik Debug Monitor Server.</a> 118 </p> 119 120 <p>To create the trace files, include the {@link android.os.Debug} class and call one of the 121 {@link android.os.Debug#startMethodTracing() startMethodTracing()} methods. In the call, you 122 specify a base name for the trace files that the system generates. To stop tracing, call {@link 123 android.os.Debug#stopMethodTracing() stopMethodTracing()}. These methods start and stop method 124 tracing across the entire virtual machine. For example, you could call 125 {@link android.os.Debug#startMethodTracing() startMethodTracing()} in 126 your activity's {@link android.app.Activity#onCreate onCreate()} method, and call 127 {@link android.os.Debug#stopMethodTracing() stopMethodTracing()} in that activity's 128 {@link android.app.Activity#onDestroy()} method.</p> 129 <pre> 130 // start tracing to "/sdcard/calc.trace" 131 Debug.startMethodTracing("calc"); 132 // ... 133 // stop tracing 134 Debug.stopMethodTracing(); 135 </pre> 136 137 <p>When your application calls startMethodTracing(), the system creates a file called 138 <code><trace-base-name>.trace</code>. This contains the binary method trace data and a 139 mapping table with thread and method names.</p> 140 141 <p>The system then begins buffering the generated trace data, until your application calls 142 stopMethodTracing(), at which time it writes the buffered data to the output file. If the system 143 reaches the maximum buffer size before stopMethodTracing() is called, the system stops tracing 144 and sends a notification to the console.</p> 145 146 <p>Interpreted code will run more slowly when profiling is enabled. Don't try to generate 147 absolute timings from the profiler results (i.e. "function X takes 2.5 seconds to run"). The 148 times are only useful in relation to other profile output, so you can see if changes have made 149 the code faster or slower.</p> 150 151 <p>When using the Android emulator, you must specify an SD card when you create your AVD because the trace files 152 are written to the SD card. Your application must have permission to write to the SD card as well. 153 154 <h2 id="copyingfiles">Copying Trace Files to a Host Machine</h2> 155 156 <p>After your application has run and the system has created your trace files 157 <code><trace-base-name>.trace</code> on a device or emulator, you must copy those files to 158 your development computer. You can use <code>adb pull</code> to copy the files. Here's an example 159 that shows how to copy an example file, calc.trace, from the default location on the emulator to 160 the /tmp directory on the emulator host machine:</p> 161 <pre> 162 adb pull /sdcard/calc.trace /tmp 163 </pre> 164 165 <h2 id="runningtraceview">Viewing Trace Files in Traceview</h2> 166 167 <p>To run Traceview and view the trace files, enter <code>traceview 168 <trace-base-name></code>. For example, to run Traceview on the example files copied in the 169 previous section, use:</p> 170 <pre> 171 traceview /tmp/calc 172 </pre> 173 174 <p class="note"><strong>Note:</strong> If you are trying to view the trace logs of an application 175 that is built with ProGuard enabled (release mode build), some method and member names might be obfuscated. 176 You can use the Proguard <code>mapping.txt</code> file to figure out the original unobfuscated names. For more information 177 on this file, see the <a href="{@docRoot}tools/help/proguard.html">Proguard</a> documentation.</p> 178 179 <h2 id="dmtracedump">Using dmtracedump</h2> 180 181 <p><code>dmtracedump</code> is a tool that gives you an alternate way of generating 182 graphical call-stack diagrams from trace log files. The tool uses the Graphviz Dot utility to 183 create the graphical output, so you need to install Graphviz before running dmtracedump.</p> 184 185 <p>The dmtracedump tool generates the call stack data as a tree diagram, with each call 186 represented as a node. It shows call flow (from parent node to child nodes) using arrows. The 187 diagram below shows an example of dmtracedump output.</p> 188 <img src= 189 "{@docRoot}images/tracedump.png" 190 width="485" 191 height="401" /> 192 <p class="image-caption"><strong>Figure 3.</strong> Screenshot of dmtracedump</p> 193 194 <p>For each node, dmtracedump shows <code><ref> 195 <em>callname</em> (<inc-ms>, <exc-ms>,<numcalls>)</code>, where</p> 196 197 <ul> 198 <li><code><ref></code> -- Call reference number, as used in trace logs</li> 199 200 <li><code><inc-ms></code> -- Inclusive elapsed time (milliseconds spent in method, 201 including all child methods)</li> 202 203 <li><code><exc-ms></code> -- Exclusive elapsed time (milliseconds spent in method, 204 not including any child methods)</li> 205 206 <li><code><numcalls></code> -- Number of calls</li> 207 </ul> 208 209 <p>The usage for dmtracedump is:</p> 210 <pre> 211 dmtracedump [-ho] [-s sortable] [-d trace-base-name] [-g outfile] <trace-base-name> 212 </pre> 213 214 <p>The tool then loads trace log data from <code><trace-base-name>.data</code> and 215 <code><trace-base-name>.key</code>. The table below lists the options for dmtracedump.</p> 216 217 <table> 218 <tr> 219 <th>Option</th> 220 221 <th>Description</th> 222 </tr> 223 224 <tr> 225 <td><code>-d <trace-base-name></code></td> 226 227 <td>Diff with this trace name</td> 228 </tr> 229 230 <tr> 231 <td><code>-g <outfile></code></td> 232 233 <td>Generate output to <outfile></td> 234 </tr> 235 236 <tr> 237 <td><code>-h</code></td> 238 239 <td>Turn on HTML output</td> 240 </tr> 241 242 <tr> 243 <td><code>-o</code></td> 244 245 <td>Dump the trace file instead of profiling</td> 246 </tr> 247 248 <tr> 249 <td><code>-d <trace-base-name></code></td> 250 251 <td>URL base to the location of the sortable javascript file</td> 252 </tr> 253 254 <tr> 255 <td><code>-t <percent></code></td> 256 257 <td>Minimum threshold for including child nodes in the graph (child's inclusive time as a 258 percentage of parent inclusive time). If this option is not used, the default threshold 259 is 20%.</td> 260 </tr> 261 </table> 262 263 264 265 <h2 id="knownissues">Traceview Known Issues</h2> 266 267 <dl> 268 <dt>Threads</dt> 269 270 <dd> 271 Traceview logging does not handle threads well, resulting in these two problems: 272 273 <ol> 274 <li>If a thread exits during profiling, the thread name is not emitted;</li> 275 276 <li>The VM reuses thread IDs. If a thread stops and another starts, they may get the same 277 ID.</li> 278 </ol> 279 </dd> 280 281 </dl> 282
