1page.title=Profiling with Traceview and dmtracedump 2parent.title=Debugging 3parent.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 load the log files in Traceview, which displays the log data in two panels:</p> 42 43 <ul> 44 <li>A <a href="#timelinepanel">timeline panel</a> -- describes when each thread and method 45 started and stopped</li> 46 47 <li>A <a href="#timelinepanel">profile panel</a> -- provides a summary of what happened inside 48 a method</li> 49 </ul> 50 51 <p>The sections below provide addition information about the traceview output panes.</p> 52 53 <h3 id="timelinepanel">Timeline Panel</h3> 54 55 <p>Figure 1 shows a close up of the timeline panel. Each thread’s execution is shown 56 in its own row, with time increasing to the right. Each method is shown in another color (colors 57 are reused in a round-robin fashion starting with the methods that have the most inclusive time). 58 The thin lines underneath the first row show the extent (entry to exit) of all the calls to the 59 selected method.</p> 60 61 <img src="{@docRoot}images/traceview_timeline.png" 62 alt="Traceview timeline panel" 63 width="893" 64 height="284" /> 65 <p class="img-caption"><strong>Figure 1.</strong> The Traceview Timeline Panel</p> 66 67 <h3 id="profilepanel">Profile Panel</h3> 68 69 <p>Figure 2 shows the profile pane, a summary of all the time spent 70 in a method. The table shows both the inclusive and exclusive times (as well as the percentage of 71 the total time). Exclusive time is the time spent in the method. Inclusive time is the time spent 72 in the method plus the time spent in any called functions. We refer to calling methods as 73 "parents" and called methods as "children." When a method is selected (by clicking on it), it 74 expands to show the parents and children. Parents are shown with a purple background and children 75 with a yellow background. The last column in the table shows the number of calls to this method 76 plus the number of recursive calls. The last column shows the number of calls out of the total 77 number of calls made to that method. In this view, we can see that there were 14 calls to 78 <code>LoadListener.nativeFinished();</code> looking at the timeline panel shows that one of those calls took 79 an unusually long time.</p> 80 81 <img src="{@docRoot}images/traceview_profile.png" 82 alt="Traceview profile panel." 83 width="892" 84 height="630" /> 85 <p class="img-caption"><strong>Figure 2.</strong> The Traceview Profile Panel</p> 86 87 <h2 id="creatingtracefiles">Creating Trace Files</h2> 88 89 <p>To use Traceview, you need to generate log files containing the trace information you want to 90 analyze.</p> 91 92 <p>There are two ways to generate trace logs:</p> 93 <ul> 94 <li>Include the {@link android.os.Debug} class in your code and call its 95 methods such as {@link android.os.Debug#startMethodTracing()} and {@link 96 android.os.Debug#stopMethodTracing()}, to start and stop logging of trace information to disk. 97 This option is very precise because 98 you can specify exactly where to start and stop logging trace data in your code.</li> 99 <li>Use the method profiling feature of DDMS to generate trace logs. This option is less 100 precise because you do not modify code, but rather specify when to start and stop logging with 101 DDMS. Although you have less control on exactly where logging starts and stops, 102 this option is useful if you don't have access to the application's code, or if you do 103 not need precise log timing. 104 </li> 105 </ul> 106 107 <p>Before you start generating trace logs, be aware of the following restrictions:</p> 108 <ul> 109 <li>If you are using the {@link android.os.Debug} class, 110 your application must have permission to write to external storage 111 ({@link android.Manifest.permission#READ_EXTERNAL_STORAGE}). </li> 112 <li>If you are using DDMS: 113 <ul> 114 <li>Android 2.1 and earlier devices must 115 have an SD card present and your application must have permission to write to the SD card. 116 <li>Android 2.2 and later devices do not need an SD card. The trace log files are 117 streamed directly to your development machine.</li> 118 </ul> 119 </li> 120 </ul> 121 122 <p>This document focuses on using the {@link android.os.Debug} class to generate trace data. For more information on using DDMS 123 to generate trace data, see <a href="ddms.html#profiling">Using the Dalvik Debug Monitor Server.</a> 124 </p> 125 126 <p>To create the trace files, include the {@link android.os.Debug} class and call one of the 127 {@link android.os.Debug#startMethodTracing() startMethodTracing()} methods. In the call, you 128 specify a base name for the trace files that the system generates. To stop tracing, call {@link 129 android.os.Debug#stopMethodTracing() stopMethodTracing()}. These methods start and stop method 130 tracing across the entire virtual machine. For example, you could call 131 {@link android.os.Debug#startMethodTracing() startMethodTracing()} in 132 your activity's {@link android.app.Activity#onCreate onCreate()} method, and call 133 {@link android.os.Debug#stopMethodTracing() stopMethodTracing()} in that activity's 134 {@link android.app.Activity#onDestroy()} method.</p> 135 <pre> 136 // start tracing to "/sdcard/calc.trace" 137 Debug.startMethodTracing("calc"); 138 // ... 139 // stop tracing 140 Debug.stopMethodTracing(); 141</pre> 142 143 <p>When your application calls {@link android.os.Debug#startMethodTracing() startMethodTracing()}, 144 the system creates a file called 145 <code><trace-base-name>.trace</code>. This contains the binary method trace data and a 146 mapping table with thread and method names.</p> 147 148 <p>The system then begins buffering the generated trace data, until your application calls 149 {@link android.os.Debug#stopMethodTracing() stopMethodTracing()}, at which time it writes 150 the buffered data to the output file. If the system 151 reaches the maximum buffer size before you call {@link android.os.Debug#stopMethodTracing() 152 stopMethodTracing()}, the system stops tracing 153 and sends a notification to the console.</p> 154 155 <p>Interpreted code runs more slowly when profiling is enabled. Don't try to generate 156 absolute timings from the profiler results (such as, "function X takes 2.5 seconds to run"). The 157 times are only useful in relation to other profile output, so you can see if changes have made 158 the code faster or slower relative to a previous profiling run.</p> 159 160 <h2 id="copyingfiles">Copying Trace Files to a Host Machine</h2> 161 162 <p>After your application has run and the system has created your trace files 163 <code><trace-base-name>.trace</code> on a device or emulator, you must copy those files to 164 your development computer. You can use <code>adb pull</code> to copy the files. Here's an example 165 that shows how to copy an example file, calc.trace, from the default location on the emulator to 166 the /tmp directory on the emulator host machine:</p> 167 <pre> 168adb pull /sdcard/calc.trace /tmp 169</pre> 170 171 <h2 id="runningtraceview">Viewing Trace Files in Traceview</h2> 172 173 <p>To run Traceview and view the trace files, enter <code>traceview 174 <trace-base-name></code>. For example, to run Traceview on the example files copied in the 175 previous section, use:</p> 176 <pre> 177traceview /tmp/calc 178</pre> 179 180 <p class="note"><strong>Note:</strong> If you are trying to view the trace logs of an application 181 that is built with ProGuard enabled (release mode build), some method and member names might be obfuscated. 182 You can use the Proguard <code>mapping.txt</code> file to figure out the original unobfuscated names. For more information 183 on this file, see the <a href="{@docRoot}tools/help/proguard.html">Proguard</a> documentation.</p> 184 185 <h2 id="dmtracedump">Using dmtracedump</h2> 186 187 <p><code>dmtracedump</code> is a tool that gives you an alternate way of generating 188 graphical call-stack diagrams from trace log files. The tool uses the Graphviz Dot utility to 189 create the graphical output, so you need to install Graphviz before running dmtracedump.</p> 190 191 <p>The dmtracedump tool generates the call stack data as a tree diagram, with each call 192 represented as a node. It shows call flow (from parent node to child nodes) using arrows. The 193 diagram below shows an example of dmtracedump output.</p> 194 <img src= 195 "{@docRoot}images/tracedump.png" 196 width="485" 197 height="401" /> 198 <p class="img-caption"><strong>Figure 3.</strong> Screenshot of dmtracedump</p> 199 200 <p>For each node, dmtracedump shows <code><ref> 201 <em>callname</em> (<inc-ms>, <exc-ms>,<numcalls>)</code>, where</p> 202 203 <ul> 204 <li><code><ref></code> -- Call reference number, as used in trace logs</li> 205 206 <li><code><inc-ms></code> -- Inclusive elapsed time (milliseconds spent in method, 207 including all child methods)</li> 208 209 <li><code><exc-ms></code> -- Exclusive elapsed time (milliseconds spent in method, 210 not including any child methods)</li> 211 212 <li><code><numcalls></code> -- Number of calls</li> 213 </ul> 214 215 <p>The usage for dmtracedump is:</p> 216 <pre> 217dmtracedump [-ho] [-s sortable] [-d trace-base-name] [-g outfile] <trace-base-name> 218</pre> 219 220 <p>The tool then loads trace log data from <code><trace-base-name>.data</code> and 221 <code><trace-base-name>.key</code>. The table below lists the options for dmtracedump.</p> 222 223 <table> 224 <tr> 225 <th>Option</th> 226 227 <th>Description</th> 228 </tr> 229 230 <tr> 231 <td><code>-d <trace-base-name></code></td> 232 233 <td>Diff with this trace name</td> 234 </tr> 235 236 <tr> 237 <td><code>-g <outfile></code></td> 238 239 <td>Generate output to <outfile></td> 240 </tr> 241 242 <tr> 243 <td><code>-h</code></td> 244 245 <td>Turn on HTML output</td> 246 </tr> 247 248 <tr> 249 <td><code>-o</code></td> 250 251 <td>Dump the trace file instead of profiling</td> 252 </tr> 253 254 <tr> 255 <td><code>-d <trace-base-name></code></td> 256 257 <td>URL base to the location of the sortable javascript file</td> 258 </tr> 259 260 <tr> 261 <td><code>-t <percent></code></td> 262 263 <td>Minimum threshold for including child nodes in the graph (child's inclusive time as a 264 percentage of parent inclusive time). If this option is not used, the default threshold 265 is 20%.</td> 266 </tr> 267 </table> 268 269 270 271 <h2 id="knownissues">Traceview Known Issues</h2> 272 273 <dl> 274 <dt>Threads</dt> 275 276 <dd> 277 Traceview logging does not handle threads well, resulting in these two problems: 278 279 <ol> 280 <li>If a thread exits during profiling, the thread name is not emitted;</li> 281 282 <li>The VM reuses thread IDs. If a thread stops and another starts, they may get the same 283 ID.</li> 284 </ol> 285 </dd> 286 287 </dl> 288
